Qgis extract by expression How to do this in QGIS? How to use the Extract by Location tool in QGIS In this video, we describe how to extract attributes from a point layer to a polygon layer. com Mar 16, 2016 · QGIS version 3. 6K subscribers Subscribed May 26, 2016 · QGIS - Select by expression - howto make multiple selections/querys Asked 9 years, 5 months ago Modified 9 years, 5 months ago Viewed 3k times Using QGIS in the operation 'select by expression' how is the correct expression to select multiple field value? ex. In this example, I want to filter or select contour which has more than 300 meters. Type your criteria. The video shows how to Select by Expression using QGIS 3. See full list on mapscaping. Click OK and then you should see the selected Jun 1, 2022 · Expression for extracting specific parts/geometries from dataset in QGIS Ask Question Asked 3 years, 5 months ago Modified 3 years, 5 months ago Apr 24, 2023 · Use the QGIS Extract by expression algorithm with the following expression: "Field" > 0 Replace Field with your field name, set where to save the results and then run the algorithm. Jul 10, 2020 · I am trying to use select by expression or extract by expression in QGIS Graphical Modeler. 6 days ago · 24. Sep 8, 2020 · How can I "extract by expression" the N first (10 highest values of one column, for example) I need it for the graphical modeler. Frequently asked questions about handling NULL values in QGIS: Oct 23, 2025 · 11. Extract by expression Creates two vector layers from an input layer: one will contain only matching features while the second will contain all the non-matching features. At a high lev The select by attribute algorithm provided by QGIS only allows you to enter a single value at a time - is there a simple tool/method to enter an expression to select multiple values from a dataset, and which can be incorporated in the graphical modeler? Mar 2, 2018 · I would like to select objects from the attribute table based on multiple attributes. You will learn how to process with Land Use Land Cover (LULC) rasters in QGIS to extract certain types Jun 5, 2023 · I will be using the Extract by Expression tool with a custom function, but I don't know how to write such a condition in a way that returns TRUE for all features in valid clusters. For more information about expressions see the Expressions. 1. core import QgsFeatureRequest from datetime import timedelta Extract Multiple Vectors by Attribute or Expression or any other method I am trying to extract multiple polygons from an ERSI Shapefile based Project, by attribute or expression or any other method, and populate the Layers window with temporary layers for each polygon. Mar 12, 2025 · pyqgis qgis-processing extract qgis-expression Improve this question edited Apr 21 at 20:45 Taras ♦ Jul 3, 2022 · Attribute Query in QGIS | Select by Expression in QGIS | Expression Builder | Attributes Table Surveying Solutions 8. Oct 23, 2025 · 24. 24. This expression worked here. For more information about expressions see the :ref:`vector_expressions`. 16-Hannover OS Version Linux Mint 19. #Select by Expression #QGIS #QGIS 3. It takes an integer input and uses 'Extract by Expression' algorithm to extract the matching feature from the input. Oct 31, 2025 · Advanced Raster Analysis (QGIS3) ¶ In the previous tutorial Basic Raster Styling and Analysis (QGIS3), you learnt about performing raster algebra with Raster Calculator. Ideal for Oct 23, 2025 · 9. This tutorial builds on these techniques and shows you how to use other raster analysis tools from the Processing Toolbox. List of functions Edit on GitHub Learn how to contribute! Dec 4, 2020 · I am building a model that includes a 'select by attribute' algorithm, and I am attempting to select by multiple fields where the value matches a model input. In the following example, I will demonstrate to extract data from a point layer. model3 . I can agg Sep 2, 2024 · Using the QGIS Processing framework, I have a set of points that I would like to buffer. What I have at the moment cannot be correctly interpreted by Extract by Expression: from qgis. This tutorial covers "Select by Expression", attribute queries, and how to extract specific features from layers. Open QGIS. This can be very useful when you have information stored as points (data, research) and want to paste it . 28. Expressions with features To evaluate an expression against a feature, a QgsExpressionContext object has to be created and passed to the evaluate function in order to allow the expression to access the feature’s field values. 10. The Expression string builder Main dialog to build expressions, the Expression string builder is available from many parts in QGIS and, can particularly be accessed when: clicking the button; selecting features with the Select By Expression… tool; editing attributes with e. Creates a vector layer that only contains features matching a QGIS expression from an input layer. 24#Vector#Data#Expression#Analysis#kenya Nov 9, 2019 · I think you would not have difficulty in doing what you are looking for with the Extract by location (intersect predicate) algorithm, instead of the Extract by expression one. 2 I wan't to aggregate values from an array field. My problem is that I can't link the extract by expression with the input multiple input. For this aggregation I'm using a filter to compare matching id's and return value from another field. I can build an expression to select the features I want, but I'm trying build a model to select and extract these features for a parameter integer from 1 to 99, so I need a way to build the select features using an expression that has a parameter in the Jun 25, 2024 · Advanced QGIS | Hpw to Query using Extract by expression Geospatial Analysis 13. 68K subscribers 54 Dec 2, 2022 · What is the bug or the crash? If I try to use the "extract by expression" with a pre-computed expression and a model parameter, the algorithm doesn't work. The expression is added as 'Pre-calculated Value' input in the algorithm. g. Level up with Expressions 9. The following example shows how to create a feature with a field called “Column” and how to add this feature to the expression context. But I need a way to automatize this. Is this the expected behavior ? Steps to Oct 25, 2016 · I want to extract certain values of a raster image in order to create a new raster which then should only contain the extracted/chosen values. In each layer, I want to extract the entities having a specific key and val QGIS Algorithm provided by QGIS (native c++) Extract by expression (native:extractbyexpression). I need apply different buffer radii to different 'sets' within my points, based on their name. 25. 14. Sep 5, 2018 · regexp_substr( "Text", '/(\\d*)\_' ) based on this working example: Obtaining specific part of string from field in QGIS attribute table? However, the expression does not give the desired result in my case: Does anyone know any way to modify/accommodate the expression? Jul 30, 2020 · Consider the attached test. 3 So I am trying to run a simple Extract by location algorithm in the graphical modeler I have as Input a polygon file with a field call NUMPO Learn how to use the Query tool in QGIS for data filtering and analysis. The criteria for adding features to the resulting layer is based on a QGIS expression. Sep 1, 2020 · I have tried several times to run “extract by expression” algorithm in Model Builder with the following expression, but system always crashes, maybe there is something wrong: CASE WHEN @ Extract by expression Creates two vector layers from an input layer: one will contain only matching features while the second will contain all the non-matching features. Jan 18, 2019 · To export features from expression in the modeler, first you need to Extract features by expression instead of select them. Jul 3, 2022 · The Extract by Attribute tool in QGIS is a very useful tool to extract data from a vector layer and then automatically create a new layer from the result. Check the attribute table after Select by expression or export selection to a new layer. Essentially, I want the selection quer Oct 29, 2025 · Extend lines Extract M values Extract specific vertices Extract vertices Extract Z values Filter vertices by M value Filter vertices by Z value Fix geometries Force right-hand-rule Geodesic line split at antimeridian Geometry by expression Interpolate point on line Keep N biggest parts Line substring Lines to polygons Merge lines Minimum Dec 23, 2020 · In a calculated field in QGIS 3. When running, the algorithm fails and log shows the value EXPRESSION: None . Extracting individually seems tedious if there is a more efficient way. Mar 18, 2020 · Refering to this post and particulary the etrimaille's comment, I want to clean my dataset created from OSM data in QGIS. Expressions The Expression string builder The Interface Writing an expression Some use cases of expressions Saving Expressions Function Editor 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 In this section, we will learn about operators and conditions used in QGIS expressions and learn how to use them to select and extract features from layers. the Field calculator tool; QGIS User Guide 9. Sep 29, 2021 · Use the algorithm extract by expression, using the following expression QGIS: Select features visible in map extent Use the algorithm package layer to save the result into a geopackage. City NAME = ROME and NAPLES (expression is invalid) Oct 14, 2019 · To select features using an expression, follow these steps From the attribute toolbar, click Select Features by Expression On the Select by Expression window, type or double click the column we want to use. I'm trying to build a model using the graphical builder model to select features from a layer where an attribute equals a parameter number. Dec 11, 2020 · What is clear: When using QGIS expressions on a layer, it is possible to relate to features of another layer with get_feature(layer,attribute,value) (enter the value and get the first feature with this value) or get_feature_by_id(layer,feature_id) (you enter th id of the feature you want to get). 2. 16. I add a vector layer for input (have also tried vector features) I add the algorithm, select the input la Jul 18, 2020 · You don't see all of them when use select by extraction, but extract by expression creates a new layer. I want to select all ojects that have 'ja' in the column "BLAUWBORST", all objects that have 'ja' in the column " Apr 16, 2019 · Thanks a lot. Is ti possible to create a plugin with DB Manager and use it on Graphical modeler? This process is just a small part of my project that needs to be repeated a bunch of times, so doing this manually all the time is impossible. In this case, I use “Alti” column. In the modeler algorithm, you can define a named output. Apr 26, 2024 · Filtering and Replacing: QGIS provides tools and expressions to filter, replace, or manage NULL values, such as using conditional expressions in the Field Calculator to replace NULL with a default value or exclude them from analysis. oonbh vrezzp qqei fso7 sgto f9gtmaqx w0mq3 cr8 c03lw d7