Qgis Expression Variables

SQL Server doesn't do variable sniffing so without OPTION (RECOMPILE) it will compile a general plan as it would for OPTIMIZE FOR UNKNOWN. Variables and types The usefulness of the "Hello World" programs shown in the previous chapter is rather questionable. The last days at the QGIS developer meeting …. 12 which allow you to create preset values for use anywhere you can use an expression in QGIS. In open source QGIS software, before version 1. I don't really follow your question though. As a quick refresher, variables are a new feature in QGIS 2. Plus these can be used in data defined variables, the print composer, the Atlas generator, rule based styling etc. The solution is simply to enclose the URL in single. Support for virtual layers has also been added to DB Manager as well as to the Processing toolbox where a new 'Execute SQL' tool is available. This function allows you to retrieve any one of a bunch of properties relating to a specific map layer, including the layer CRS, metadata, source path, etc. o Long-Term Water Demand Forecast: Introduced a novel flexible approach by exploring the water demand bounds and limits through applied deep learning practices (data augmentation, data cropping, distortion/white gaussian noise, shuffled training) and predictive modeling techniques (artificial neural networks, support vector regressive models, gene expression programming). Opening the options dialog will also show a Variables group for setting “Global” variables. qm file laying in the same folder like the. Variables can be defined in three places: In the QGIS settings dialog, in the project properties dialog and in a map composition. An expression is a combination of variables constants and operators written according to the syntax of C language. This adds new variables for @symbol_color and @symbol_angle for use in labelling. Best practices for writing Python QGIS Expression Functions 2017-05-10 By mkuhn Recently there have been some questions and discussions about python based expression functions and how parameters like usesGeometry need to be used. What do the different colours in Ubuntu's ls command mean? For example, when I type the ls command in one of my folders, I get one of the files in light green, the other (which is a folder) in blue. exe when your path contains c:\msys\local\bin and c:\msys\local\lib directories, so the DLLs will be used from that place. When building expressions in the Raster Calculator tool, clicking and double-clicking on the various layers, variables, buttons, and tool names available in the dialog box will help you to avoid syntax errors that may otherwise be made while typing. - Allows for adding on the fly functions to the expression engine. A prior familiarity with basic QGIS capabilities is assumed. I have a function which can model more than two variables at a time. Creates a new expression based on the provided string. The function takes a single argument, the id for an item inside the composition, and returns a map of variable name to value for that item. QgsExpression (expr: str) ¶ Bases: sip. Any kind of vector layers can be accessed in the query, including multiple layers from different data providers to make joins. Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Default value with readonly geometry expression. Variables can be defined in three places: In the QGIS settings dialog, in the project properties dialog and in a map composition. This was a combination of two bugs: firstly, we weren't initialising the state variable field_names to NULL, and so if the variable happened to be filled with junk and we were unable to import a shape file, we would end up freeing a random pointer. I want to set environment variables for QGIS in Win7. The values in those expressions can change. variables Min. I have FULLNAME in coastalroads, but that doesn't work. 12 which allow you to create preset values for use anywhere you can use an expression in QGIS. I decided to make something by myself, so I've made this little integer-based TIC TAC TOE console game. the projects title, or the users full name) that can be used in expressions. The Expressions feature is available from many parts in QGIS. The research aim was to investigate the user’s aesthetic perception in relation to the adoption of different management measures, within an Italian metropolitan Natura 2000 site. open the tabular data in QGIS using Add Vector Layer 3. And there you have it. 49 minutes ago · I created an 'imageviewer. Expression based labeling now in QGIS and the new expression builder. In Expression you see the calculation expressions you create with the Function List. 3 64bit was used to prepare the data for animated map visualization of Alaska’s forest damage. QGIS is a free, open source, cross platform (lin/win/mac) geographical information system (GIS) - qgis/QGIS This adds a new item_variables expression function when expressions are used inside a composition context. QGIS Issue Tracking. This isn’t strictly related to variables, but another new feature which was introduced in QGIS 2. In open source QGIS software, before version 1. csv (this is variable $2) the bracketed comments wont be in the execution its just for explanation the second variable here should be checked in that statement to see if the file exists to continue but it doesn't do this. Woodrow) you have a function called NamePathActiveLayer that almost does the job (you have at least file name of active layer ) or (better, i suppose) : write your own expression, go in the expression dialog box, activate the function editor tab and try the following code :. the projects title, or the users full name) that can be used in expressions. MATTHIAS KUHN - QGIS core committer, QField, Project variable in qfield. This function allows you to retrieve any one of a bunch of properties relating to a specific map layer, including the layer CRS, metadata, source path, etc. As a quick refresher, variables are a new feature in QGIS 2. I have been learning C++ for 3 months now. Anita Graser. Preparing Data for Animation in QGIS. QGIS' Composer has the ability to create an "Atlas" built-in. [QGIS-Developer] expression variable for rendering with QGIS server Dear developers, I use expression variables within the rule based renderer. Click the Expression button. When a variable is used in an expression, it is substituted by its value or the variable's definition. In addition to the numerous pre-defined variables, you can also define your own ones. The European Commission promotes management practices for nature conservation and human well-being, requiring the involvement of users in Natura 2000 sites. It would be less nasty doing the count in Python than to generate a nasty-looking CASE expression. This is only useful for complicated expressions, where the same calculated value needs to be used in different places. Available with Image Analyst license. 12 which allow you to create preset values for use anywhere you can use an expression in QGIS. We had to write several lines of code, compile them, and then execute the resulting program, just to obtain the result of a simple sentence written on the screen. [QGIS-Developer] expression variable for rendering with QGIS server Dear developers, I use expression variables within the rule based renderer. Using variables will ensure that the template is automatically updated with the right details for the current project. Bingo!! That was cool. Optional parameters in QGIS Processing scripts & models. 12 was a new "layer_property" expression function. Please also see the answer to QGIS query syntax differs between attribute table and feature filter for detailed information about the difference. A meter or measure is referenced as a section variable by placing the section name in brackets []. - Expression Dialog: Added support for QGIS variables and recent expressions. Plus these can be used in data defined variables, the print composer, the Atlas generator, rule based styling etc. A new version of this tutorial is available at Using Custom Python Expression Functions (QGIS3) Expressions in QGIS have a lot of power and are used in many core features - selection, calculating field values, styling, labelling etc. This little feature was suggested by Mathieu Pellerin, who is always pushing the boundaries of QGIS’ cartographic tools and coming up with great ideas for new styling features (you can check out some of his work via Flickr). 7 on Ubuntu 16. Let’s imagine a typical map project. 1: Create New Variables in a Shapefile 13 of 19 • To calculate the new variable, you can multiply the estimated number of women of reproductive age by district extracted from the AfriPop raster dataset using the QGIS zonal statistics plug-in (variable WRA2010AFR) by the HIV prevalence. Now we are ready to perform the spatial query. Nora has 13 jobs listed on their profile. At one point you seem to be saying that the version without the hint is "much much faster" and then later you say the version with the hint is "much better". This isn't strictly related to variables, but another new feature which was introduced in QGIS 2. Support for virtual layers has also been added to DB Manager as well as to the Processing toolbox where a new 'Execute SQL' tool is available. Or to select a row and highlight all variables which are in the row. In this workshop, you will build gain some basic, yet highly useful skills for creating and editing vector datasets in QGIS. Overview of the task ¶ The tutorial shows how to create a map of Japan with standard map elements like map inset, grids, north arrow, scale bar and labels. QGIS is a free, open source, cross platform (lin/win/mac) geographical information system (GIS) - qgis/QGIS This adds a new item_variables expression function when expressions are used inside a composition context. A simple SQL expression. edu is a platform for academics to share research papers. Plus these can be used in data defined variables, the print composer, the Atlas generator, rule based styling etc. Let's imagine a typical map project. curl outfile variable not working in bash script. Examples where Expression Functions (EFns) can be used in QGIS are: symbology, labeling, calculating fields, defining virtual fields, selecting and filtering data, layouts, atlas serial printing and reports, map tips, custom python expressions, parameters for processing, and many more. values from 100-1000, increasing by 50) A "Calculate by Expression" option allows for updating existing batch table cells using the results of a QGIS expression. View Nora Forbes' profile on LinkedIn, the world's largest professional community. \$\begingroup\$ Now that it has been clarified that this is a QGIS expression, I suggest that you write a custom Python function that can be incorporated into the expression. A simple SQL expression. La fonctionnalité des Expressions est disponible dans de nombreuses composantes de QGIS. something like 2x+3y A term is a number or a letter or a combination. You load up QGIS, throw a bunch of layers on your map, and then get stuck into styling and labelling them 'just right'. This isn't strictly related to variables, but another new feature which was introduced in QGIS 2. This adds new variables for @symbol_color and @symbol_angle for use in labelling. In QGIS, you can use variables to store useful recurrent values (e. 0 brings a massive list of new changes - the highlights of which we will try to cover here. Is it possible to access the QGIS Map Canvas as a variable or expression value to be used in the field calculator or labelling engine? (i. egg" and you can find it in PyCharm's "debug-eggs" directory. The following will discuss two dimensional image filtering in the frequency domain. I don't really follow your question though. This time, we will use them to create a dynamic data driven style, that is, a style that automatically adjusts to the minimum and maximum values of any numeric field … and that field will be specified in a variable!. Learn ArcGIS and QGIS Simultaneously - Part 5 - Add CSV data to map and convert it to Shapefile - Duration: 8 minutes, 57 seconds. Can somebody walk me through the steps?. Sets the original value variable value for the context. Expressions in QGIS are more and more widely used for all kinds of purposes. something like 2x+3y A term is a number or a letter or a combination. reclass , in the dialog box the MDE is selected, in the text box Reclass Rules we place the expression that defines the intervals:. 7 on Ubuntu 16. The values in those expressions can change. Image Classification with RandomForests in R (and QGIS) I’m using the expression img * (img >= 0) to of class SpatialPolygonsDataFrame and let’s create a variable to store the name of. Let’s imagine a typical map project. go to the Shapefile layer PROPERTIES - JOINS tab, and run the join, using the KML. TODO: Add screenshots. So almost all algorithms from this provider will work "out of the box" without any additional configuration. This function allows you to retrieve any one of a bunch of properties relating to a specific map layer, including the layer CRS, metadata, source path, etc. When a variable is used in an expression, it is substituted by its value or the variable's definition. expressions package points to the qgis2\python\expressions package in the users home. View Nora Forbes’ profile on LinkedIn, the world's largest professional community. with_variable(name, value, node): This function sets a variable for any expression code that will be provided as 3rd argument. 11 minutes ago · I have a binary dependent variable (infection + or -) and both continuous and categorical independent variables. Exercise using QGIS. Examples of using a variable in an expression. Introduction. , every expression results in some value of a certain type that can be assigned to a variable. As a quick refresher, variables are a new feature in QGIS 2. Deeply attracted to Nature, Arts and all forms of expression, I feel especially drawn to biology, psychology, spirituality, healing processes and wholistic health. Based on layer data and prebuilt or user defined functions, Expressions offer a powerful way to manipulate attribute value, geometry and variables in order to dynamically change the geometry style, the content or position of the label, the value for diagram, the height of a layout item, select some features, create virtual field …. One continuous independent variable (BMI) seems to be nonlinear in that the lowest and highest BMI are more likely to be + and the BMI values in the middle are less likely to be +. The array of functions and variables available in the QGIS select by expression window is awesome, especially when compared with ArcGIS which has just string, date and numeric. For optimization prepare() should always be called before every loop in which this expression is used. QGIS is a free and open source desktop Geographical Information Systems (GIS) package. This adds new variables for @symbol_color and @symbol_angle for use in labelling. You load up QGIS, throw a bunch of layers on your map, and then get stuck into styling and labelling them 'just right'. For example: If you have crime locations in a city, you can use spatial regression to understand the factors behind patterns of crime. This isn't strictly related to variables, but another new feature which was introduced in QGIS 2. QgsExpression(other: QgsExpression) Create a copy of this expression. When you learn these 7 geoprocessing tools, you develop a good baseline of GIS skills. QGIS Issue Tracking. curl outfile variable not working in bash script. In a recent post, we used aggregates for labeling purposes. I created an 'imageviewer. QGIS is a free and open-source cross-platform desktop geographic information system (GIS) application that supports viewing, editing, visualization and analysis of geospatial data. Available with Image Analyst license. The user typed in. On top of that, you are one step closer to becoming a GIS guru. Exploring variables in QGIS pt 3: layer level variables In part 3 of my exploration of variables in QGIS 2. An option to add calculated values from a QGIS expression, allowing complex range-based values to be added to the dialog (e. I have knowledge to handle GIS software for instance: ArcGIS, Qgis, MapInfo, gvSIG. 12 which allow you to create preset values for use anywhere you can use an expression in QGIS. Hence, RQGIS extends R's. Ireland QGIS User Group Blog. I'm using the open source GIS (QGIS) and I want to use the python field calculator. So here is a neat trick. References #3638 2018-07-21 22:42 Regina Obe * [r16658] Put in refname what kind of ST_MapAlgebra (expression or callback function) Closes #2806 for PostGIS 2. Tools: Python, QGIS, Javascript, PostgreSQL • Historical earth observation and disaster data collection, cleaning and visualization using pandas, matplotlib and QGIS. The TIGER layer is called street100k_l_or39 and the layer with the names of the roads I am trying to is called coastalroads. Download and georeference Google Earth images in QGIS 2. QGIS expression functions can also be used in queries. Graduated and Proportional Symbol Maps using QGIS 2. - Expression Dialog: Added support for QGIS variables and recent expressions. QGIS algorithm provider¶. The last days at the QGIS developer meeting 2017, I spent some time looking into and improving the performance for expressions. This is especially important if the values are far apart. rightClick() and pyautogui. \$\begingroup\$ Now that it has been clarified that this is a QGIS expression, I suggest that you write a custom Python function that can be incorporated into the expression. Here's a quick run-down on two nice new styling options which I've recently added to QGIS 2. Click on Select features using an expression button. QgsExpression (expr: str) ¶ Bases: sip. Is it possible to access the QGIS Map Canvas as a variable or expression value to be used in the field calculator or labelling engine? (i. All example data and project files are included. open the tabular data in QGIS using Add Vector Layer 3. QGIS is a free and open-source cross-platform desktop geographic information system (GIS) application that supports viewing, editing, visualization and analysis of geospatial data. Elle peut être accédée en utilisant le Constructeur d’Expression, Sélectionner à l’aide d’une Expression, l’option de couche de symbole Générateur de géometrie, la Calculatrice de champ ou l’outil de Valeurs définies par les données. We can use spatial regression to understand what variables (income, education and more) explain crime locations. The function takes a single argument, the id for an item inside the composition, and returns a map of variable name to value for that item. QGIS : Variable dans composeur d'impression Bonjour, je me demandais s'il est possible de mettre des variables dans le composeur d'impression, genre la date pour une mise à jour automatique etc. Image Classification with RandomForests in R (and QGIS) I’m using the expression img * (img >= 0) to of class SpatialPolygonsDataFrame and let’s create a variable to store the name of. The Expressions feature is available from many parts in QGIS. Introduction. I'm in continue formation throught many online courses and geotecnologies seminary. QGIS algortihm provider implements various analysis and geoprocessing operations using mostly only QGIS API. go to the Shapefile layer PROPERTIES - JOINS tab, and run the join, using the KML. Exercise using QGIS. I have an attribute table with ~ 100 fields and I want to select some fields. user module in Python. The QGIS Atlas is a true open source technique to generate hundreds of maps in minutes. I have excelent facility of interpersonal work and squad, well verbal expression and argumentative as well capacity to read and interpret techique documents. #8) Expressions and Functions. (Contributed by Terry Jan Reedy in bpo-33656. These are called section variables, and they can provide several kinds of information about the meter or measure. Creates a new expression based on the provided string. QgsExpression (expr: str) ¶ Bases: sip. Creates a new expression based on the provided string. Variables can be defined in three places: In the QGIS settings dialog, in the project properties dialog and in a map composition. Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. In QGIS, you can use variables to store useful recurrent values (e. I have an attribute table with ~ 100 fields and I want to select some fields. dll:s needed to the same directory as the qgis. SQL expressions are used in many parts of ArcGIS and its extensions to define a subset of data on which to perform some operation. Opening the options dialog will also show a Variables group for setting “Global” variables. When building expressions in the Raster Calculator tool, clicking and double-clicking on the various layers, variables, buttons, and tool names available in the dialog box will help you to avoid syntax errors that may otherwise be made while typing. Lets say you wanted to. Changelog for QGIS 3. The easiest way to do this is through the "Project Properties" dialog, under the "Variables" section: Default project. Test script to randomly generate n points unniformly distributed within a polygon extent. An option to add calculated values from a QGIS expression, allowing complex range-based values to be added to the dialog (e. I don't know SQL well and. Default value with readonly geometry expression. Let’s imagine a typical map project. The last days at the QGIS developer meeting …. It can be accessed using the Expression Builder, the Select By Expression, the Geometry generator symbol layer option, the Field calculator or the Data defined override tool. On top of that, you are one step closer to becoming a GIS guru. As a quick refresher, variables are a new feature in QGIS 2. Under System variables, find the variable with the name Path. QGIS : Variable dans composeur d'impression Bonjour, je me demandais s'il est possible de mettre des variables dans le composeur d'impression, genre la date pour une mise à jour automatique etc. QgsExpression (expr: str) ¶ Bases: sip. You load up QGIS, throw a bunch of layers on your map, and then get stuck into styling and labelling them 'just right'. Means, it makes the translation according to a Qt Compiled Translation Source File (. The research aim was to investigate the user’s aesthetic perception in relation to the adoption of different management measures, within an Italian metropolitan Natura 2000 site. And variables, there's a bunch of ways you can think about them, but they're really just values in expressions where they can change. The easiest way to do this is through the "Project Properties" dialog, under the "Variables" section: Default project. A meter or measure is referenced as a section variable by placing the section name in brackets []. variableNames. Opening the options dialog will also show a Variables group for setting “Global” variables. So here is a neat trick. Exercise using QGIS. 2 with Cinnamon desktop. Dynamic styling expressions with aggregates & variables. so that you can create an expression that selects/interrogates features that are visible/present in a particular view of the canvas in a similar way that the print composer 'filters the legend by map content'). =Variables!GroupTotal. qgs file, having the same name like the. Using the expression tool to create a calculated variable for a choropleth map in QGIS. This isn't strictly related to variables, but another new feature which was introduced in QGIS 2. Let’s imagine a typical map project. The course covers the following topics: 1. - The plugin now deals with Adding/Removing fields in an edit session. This is only useful for complicated expressions, where the same calculated value needs to be used in different places. \$\begingroup\$ Now that it has been clarified that this is a QGIS expression, I suggest that you write a custom Python function that can be incorporated into the expression. I know how to access the layer and select the values I want:. Each category is individually matched to the symbols which exist within the specified QGIS XML style database. A specified expression (or field name) is used to create categories for the renderer, with QGIS creating a category for each unique value within the layer. 02 and I want to get the first digit 9 and store in another variable. Let's say the variable [email protected] where [email protected] from user input. An option to add calculated values from a QGIS expression, allowing complex range-based values to be added to the dialog (e. When a variable is used in an expression, it is substituted by its value or the variable's definition. Expressions¶. With the new notification system QGIS can let you know about important information via a yellow message bar that appears at the top of the map canvas but doesn't force you to deal with it if you are busy doing something else. the Field calculator tool;. This was a combination of two bugs: firstly, we weren't initialising the state variable field_names to NULL, and so if the variable happened to be filled with junk and we were unable to import a shape file, we would end up freeing a random pointer. SQL Server doesn't do variable sniffing so without OPTION (RECOMPILE) it will compile a general plan as it would for OPTIMIZE FOR UNKNOWN. Any kind of vector layers can be accessed in the query, including multiple layers from different data providers to make joins. This time, we will use them to create a dynamic data driven style, that is, a style that automatically adjusts to the minimum and maximum values of any numeric field … and that field will be specified in a variable!. Fetches a matching variable from the context. Expressions in QGIS are more and more widely used for all kinds of purposes. View Nora Forbes' profile on LinkedIn, the world's largest professional community. Exploring variables in QGIS pt 3: layer level variables In part 3 of my exploration of variables in QGIS 2. In the Add Variable dialog, type the PATH_TO_LIB variable, and its value that points to the library location on your disk. [QGIS-Developer] expression variable for rendering with QGIS server Dear developers, I use expression variables within the rule based renderer. The array of functions and variables available in the QGIS select by expression window is awesome, especially when compared with ArcGIS which has just string, date and numeric. 12 was a new "layer_property" expression function. QgsExpression (expr: str) ¶ Bases: sip. Installation, Executing Scripts, Using the interpreter; 2. For example, to click on a variable and see all containing rows. 12 is the ability to set custom variables for use in QGIS' expression engine. I don't know what the proper expression is to do this. I don't really follow your question though. The easiest way to do this is through the "Project Properties" dialog, under the "Variables" section: Default project. I don't know what the proper expression is to do this. As a quick refresher, variables are a new feature in QGIS 2. =Variables!GroupTotal. From the street100k_l_or39 attributes table I open the Select by Expression window. the Field calculator tool;. Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. An introduction to thinking in a Pythonic way covering the fundamentals of the language and putting you in good stead for the Python for QGIS course. At one point you seem to be saying that the version without the hint is "much much faster" and then later you say the version with the hint is "much better". When a variable is used in an expression, it is substituted by its value or the variable's definition. QgsExpression(other: QgsExpression) Create a copy of this expression. The array of functions and variables available in the QGIS select by expression window is awesome, especially when compared with ArcGIS which has just string, date and numeric. QGIS algortihm provider implements various analysis and geoprocessing operations using mostly only QGIS API. Returns a list of variables names set by all scopes in the context. You load up QGIS, throw a bunch of layers on your map, and then get stuck into styling and labelling them 'just right'. These are so common that ArcGIS and QGIS have added them to drop-down menus for easy access. Measures and meters can be referenced as variables. In the Add Variable dialog, type the PATH_TO_LIB variable, and its value that points to the library location on your disk. For example the recently introduced geometry generators allow drawing awesome effects with modified feature geometries on the fly. The European Commission promotes management practices for nature conservation and human well-being, requiring the involvement of users in Natura 2000 sites. These are so common that ArcGIS and QGIS have added them to drop-down menus for easy access. 12 was a new “layer_property” expression function. But then I thought do I really want to create these local variables in my sequence that only exist for the purpose of this one expression. Using variables will ensure that the template is automatically updated with the right details for the current project. And variables, there's a bunch of ways you can think about them, but they're really just values in expressions where they can change. QGIS algorithm provider¶. - Expression Dialog: Added support for QGIS variables and recent expressions. 14 Posted by Pritimoy Das on April 1, 2016 April 1, 2016 Graduated and proportional symbol maps are a class of maps that use the visual variable of size to represent differences in the magnitude of a discrete, abruptly changing phenomenon, e. Changelog for QGIS 3. Sets the original value variable value for the context. 02 and I want to get the first digit 9 and store in another variable. So the sum-- so we're going to have an addition here-- of negative 7 and the quantity. QGIS preferences (QGIS v. Expressions in QGIS are more and more widely used for all kinds of purposes. QGIS algortihm provider implements various analysis and geoprocessing operations using mostly only QGIS API. Ireland QGIS User Group Blog. 12 is the ability to set custom variables for use in QGIS' expression engine. Under System variables, find the variable with the name Path. MATTHIAS KUHN - QGIS core committer, QField, Project variable in qfield. 2 with Cinnamon desktop. A specified expression (or field name) is used to create categories for the renderer, with QGIS creating a category for each unique value within the layer. Please also see the answer to QGIS query syntax differs between attribute table and feature filter for detailed information about the difference. Let's imagine a typical map project. expression, you don't get the magical handling for #1. QGIS is a free and open-source cross-platform desktop geographic information system (GIS) application that supports viewing, editing, visualization and analysis of geospatial data. Plus these can be used in data defined variables, the print composer, the Atlas generator, rule based styling etc. Expressions in QGIS are more and more widely used for all kinds of purposes. When building expressions in the Raster Calculator tool, clicking and double-clicking on the various layers, variables, buttons, and tool names available in the dialog box will help you to avoid syntax errors that may otherwise be made while typing. QGIS Issue Tracking. reclass , in the dialog box the MDE is selected, in the text box Reclass Rules we place the expression that defines the intervals:. QGIS' Composer has the ability to create an "Atlas" built-in. 02 and I want to get the first digit 9 and store in another variable. You load up QGIS, throw a bunch of layers on your map, and then get stuck into styling and labelling them 'just right'. The array of functions and variables available in the QGIS select by expression window is awesome, especially when compared with ArcGIS which has just string, date and numeric. QGIS algorithm provider¶. Returns a map of variable name to value representing all the expression variables contained by the context. 0 brings a massive list of new changes - the highlights of which we will try to cover here. You load up QGIS, throw a bunch of layers on your map, and then get stuck into styling and labelling them 'just right'. SQL Server doesn't do variable sniffing so without OPTION (RECOMPILE) it will compile a general plan as it would for OPTIMIZE FOR UNKNOWN. > hi, > > I was trying to implement dynamic setting of Expression Variables when handling server requests (Example use case: I want to render another logo in a composition map depending on a project-variable), as I got stuck testing the behaviour of expression variables in server-requests. Now we are ready to perform the spatial query. So the sum-- so we're going to have an addition here-- of negative 7 and the quantity. [QGIS-Developer] expression variable for rendering with QGIS server Dear developers, I use expression variables within the rule based renderer. o Long-Term Water Demand Forecast: Introduced a novel flexible approach by exploring the water demand bounds and limits through applied deep learning practices (data augmentation, data cropping, distortion/white gaussian noise, shuffled training) and predictive modeling techniques (artificial neural networks, support vector regressive models, gene expression programming). qgs file and having the language-code as postfix of the users language (the language configured in the QGIS settings). A new feature for QGIS 2. Another neat thing about QGIS variables is that they can be inherited and overridden, just like CSS rules. In the map-making business, this means being efficient without compromising art and intricacy. Tom Colley - QGIS Print Composer & Advanced Atlas Production. 2 with Cinnamon desktop. Expressions¶. Separation of Variables in PDEs, regarding the separation constant is this expression still in use or is it dated? QGIS "open attribute table" as tab. The fact-checkers, whose work is more and more important for those who prefer facts over lies, police the line between fact and falsehood on a day-to-day basis, and do a great job. Today, my small contribution is to pass along a very good overview that reflects on one of Trump’s favorite overarching falsehoods. Namely: Trump describes an America in which everything was going down the tubes under  Obama, which is why we needed Trump to make America great again. And he claims that this project has come to fruition, with America setting records for prosperity under his leadership and guidance. “Obama bad; Trump good” is pretty much his analysis in all areas and measurement of U.S. activity, especially economically. Even if this were true, it would reflect poorly on Trump’s character, but it has the added problem of being false, a big lie made up of many small ones. Personally, I don’t assume that all economic measurements directly reflect the leadership of whoever occupies the Oval Office, nor am I smart enough to figure out what causes what in the economy. But the idea that presidents get the credit or the blame for the economy during their tenure is a political fact of life. Trump, in his adorable, immodest mendacity, not only claims credit for everything good that happens in the economy, but tells people, literally and specifically, that they have to vote for him even if they hate him, because without his guidance, their 401(k) accounts “will go down the tubes.” That would be offensive even if it were true, but it is utterly false. The stock market has been on a 10-year run of steady gains that began in 2009, the year Barack Obama was inaugurated. But why would anyone care about that? It’s only an unarguable, stubborn fact. Still, speaking of facts, there are so many measurements and indicators of how the economy is doing, that those not committed to an honest investigation can find evidence for whatever they want to believe. Trump and his most committed followers want to believe that everything was terrible under Barack Obama and great under Trump. That’s baloney. Anyone who believes that believes something false. And a series of charts and graphs published Monday in the Washington Post and explained by Economics Correspondent Heather Long provides the data that tells the tale. The details are complicated. Click through to the link above and you’ll learn much. But the overview is pretty simply this: The U.S. economy had a major meltdown in the last year of the George W. Bush presidency. Again, I’m not smart enough to know how much of this was Bush’s “fault.” But he had been in office for six years when the trouble started. So, if it’s ever reasonable to hold a president accountable for the performance of the economy, the timeline is bad for Bush. GDP growth went negative. Job growth fell sharply and then went negative. Median household income shrank. The Dow Jones Industrial Average dropped by more than 5,000 points! U.S. manufacturing output plunged, as did average home values, as did average hourly wages, as did measures of consumer confidence and most other indicators of economic health. (Backup for that is contained in the Post piece I linked to above.) Barack Obama inherited that mess of falling numbers, which continued during his first year in office, 2009, as he put in place policies designed to turn it around. By 2010, Obama’s second year, pretty much all of the negative numbers had turned positive. By the time Obama was up for reelection in 2012, all of them were headed in the right direction, which is certainly among the reasons voters gave him a second term by a solid (not landslide) margin. Basically, all of those good numbers continued throughout the second Obama term. The U.S. GDP, probably the single best measure of how the economy is doing, grew by 2.9 percent in 2015, which was Obama’s seventh year in office and was the best GDP growth number since before the crash of the late Bush years. GDP growth slowed to 1.6 percent in 2016, which may have been among the indicators that supported Trump’s campaign-year argument that everything was going to hell and only he could fix it. During the first year of Trump, GDP growth grew to 2.4 percent, which is decent but not great and anyway, a reasonable person would acknowledge that — to the degree that economic performance is to the credit or blame of the president — the performance in the first year of a new president is a mixture of the old and new policies. In Trump’s second year, 2018, the GDP grew 2.9 percent, equaling Obama’s best year, and so far in 2019, the growth rate has fallen to 2.1 percent, a mediocre number and a decline for which Trump presumably accepts no responsibility and blames either Nancy Pelosi, Ilhan Omar or, if he can swing it, Barack Obama. I suppose it’s natural for a president to want to take credit for everything good that happens on his (or someday her) watch, but not the blame for anything bad. Trump is more blatant about this than most. If we judge by his bad but remarkably steady approval ratings (today, according to the average maintained by 538.com, it’s 41.9 approval/ 53.7 disapproval) the pretty-good economy is not winning him new supporters, nor is his constant exaggeration of his accomplishments costing him many old ones). I already offered it above, but the full Washington Post workup of these numbers, and commentary/explanation by economics correspondent Heather Long, are here. On a related matter, if you care about what used to be called fiscal conservatism, which is the belief that federal debt and deficit matter, here’s a New York Times analysis, based on Congressional Budget Office data, suggesting that the annual budget deficit (that’s the amount the government borrows every year reflecting that amount by which federal spending exceeds revenues) which fell steadily during the Obama years, from a peak of $1.4 trillion at the beginning of the Obama administration, to $585 billion in 2016 (Obama’s last year in office), will be back up to $960 billion this fiscal year, and back over $1 trillion in 2020. (Here’s the New York Times piece detailing those numbers.) Trump is currently floating various tax cuts for the rich and the poor that will presumably worsen those projections, if passed. As the Times piece reported: