Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

Questions tagged [expression]

Expressions are SQL-like statements that are used to evaluate dynamic properties.

Filter by
Sorted by
Tagged with
1
vote
0answers
48 views

Features duplicated in multiple, different fields - label expression to avoid duplicate labels

Using ArcMap 10.4.1. I am trying to label a feature class of roads, there are 5 types: U.S. Highways, State Highways, County, Municipal, and Off Highway. Sometimes a road feature belongs to two ...
1
vote
0answers
92 views

Force expression-based map item position onto second page in Atlas setup?

I created an atlas with two pages for each atlas feature, the first being for a map and the second page being for a table. I need to separate pages as the map is using all the paper space and the ...
1
vote
0answers
64 views

Calculated sum of visible areas in print composer

I want to view the sum of area of each habitat displayed in the layout. Only the displayed habitats in the viewport. Which expression do I have to use in the textbox? Now I have calculated them manual....
1
vote
0answers
160 views

creating new fields and populating with sequential numbers based on grouping other columns

(Relatively new Qqis user) I have a vector layer (lines) for a road network - which has a field for each road name and a field for road segments - but I need to add fields for numeric IDs rather ...
1
vote
0answers
124 views

QGIS Expression Calculator Field Shows Null

When I go into the expression builder under the "Field and Values" drop down on the left side, instead of a list of field for the layer all it says is NULL. Is there something that would cause this ...
1
vote
0answers
119 views

Scale color ramp filtered on common layer columns, in QGIS

I'm creating an atlas in QGIS showing bus lines, tax fare zones, and travel flow lines. I have a layer with bus lines - one feature per bus line. Moreover, I have a layer with travel flow lines - ...
1
vote
0answers
265 views

QGIS use relations in expressions (for symbol and print composer)

I have a shapefile layer a relation linking data from a csv file. This is a one to many relationship where a parcel could have multiple entries from the csv. How do I reference that data in ...
1
vote
0answers
41 views

Add field in table with layername as value

I need to merge multiple tables (I'm planning to use "merge" for this). I also need a new column in the original tables that show the name of the source table. Is there a way I can add a field that ...
1
vote
0answers
118 views

Warning/Error message “The ) is expected” - Functional Attribute - GeoMedia Desktop

So the problem, is when I write my Expression on the Functional Attribute window in GeoMedia Pro, it gives me a warning message indicates that the ")" is expected; The expression is : ROUND(AREA(...
1
vote
0answers
63 views

MapServer - How to display only X characters of annotation LABEL (text\string) based on [field]

In MapServer how\where do you use an expression to force a label to 5 characters to appear as annotation\labels
1
vote
0answers
105 views

Data dependent override on colour and linewidth of line pattern fill not working after upgrade to QGIS 2.12

I have recently upgraded to QGIS 2.12 which has resulted in a problem with one of my projects, whereby the data dependent override of the line width and colour of a line pattern fill and SVG marker ...
1
vote
0answers
46 views

How would I build the syntax inside a request in the case I wanted to multiply 2 variables?

I would like add something to my previous question (here: How to build QgsExpressions in python?) How would I build the syntax inside this request in the case I wanted field_name to be also a ...
1
vote
0answers
70 views

Text box with automated coordinate reference system in use on Qgis

Using an expression, is it possible to automatically fill a text box placed on the map (in the composer) showing the reference coordinate system of the project? If possible, how would that expression ...
1
vote
0answers
420 views

How to define a custom function that returns value of a field in an unsaved form

Filter expression builder in QGIS 2.8 allows us to define custom functions using python. I'm intrested would it be possible to define a function which returns a value of a field in an unsaved form ...
1
vote
0answers
157 views

Masking Labeles in the Compositor in QGIS 2.8.1

I am looking for a way to remove/mask out Labels that are under a composer Element (Overview Map), which I moved in front of my main map. Is there no way to do this? Maybe using the ItemID? I tried ...
0
votes
2answers
313 views

NULL value not equal to empty value for attribute

I have a feature layer in a gdb. It has an attribute named uniqueid. Some of rows have a value for uniqueid and some do not. I am trying to select only the features that have a value (are not blank). ...
0
votes
1answer
281 views

Creating index contours using QGIS?

I'm testing out QGIS for the first time, and I'm trying to find a way to highlight index contours. I'd like to be able to do so via the layer Symbology, or if necessary by separating out the index ...
0
votes
2answers
2k views

How to select features with same values?

How can I select all those features that has exact same values in their attribute field called "X"? I think that the solution could be something like the Countif function in Excel, but I haven't found ...
0
votes
2answers
52 views

Downloading files with file paths informed by attribute information

I am looking to download files that are saved in a server location with a file path that is informed by attribute information created in the graphical modeler. The information that I would like to ...
0
votes
1answer
145 views

QGIS3 Atlas: expression to pull values from a non-coverage layer at current location?

I have an atlas composition where I would like to, in addition to attributes from my coverage layer which consists of polygons that are scattered throughout the world, place other values from another ...
0
votes
2answers
722 views

Changing colour of point based on null value using Arcade Expression in ArcGIS Online?

I have a map in ArcGIS Online with a point layer showing lighting assets. These are symbolised based on unique type (post = circle, column = square). The user will update a separate field to have a ...
0
votes
1answer
286 views

How to use FindLabel function programmatically using ArcPy?

I want to set the FindLabel function to the labelclass expression using ArcPy. My code is like How To: Label a related table. I don't want to load the function into the expression editor of the label ...
0
votes
2answers
1k views

Removing null value in labels of ArcMap?

Following this question: Label expression in ArcGIS gives TypeError coercing to Unicode need string or buffer NoneType found? I used this python expression in order to create a stacked label from ...
0
votes
1answer
67 views

Writing code expression in Calculate Value to find cell value or Minimum cell value?

I have a calculate value tool that I'm using to skip rasters without features/no data. I'm very new to python and do not know much about proper formatting and syntax. Right now, the tool works but ...
0
votes
1answer
1k views

Check that a Variable is NOT Equal to Multiple Values

I am trying to use a check a field against several values (eg: [Name] != 'NONE', and [Name] != 'N/A'). This is for the label expression builder within ArcGIS and I am using it eliminate label for ...
0
votes
1answer
52 views

Style a feature in one layer based on an attribute in another layer in Print Composer Atlas

I have two layers; one is the foreground and the other a background. Both layers have fields containing similar values (field values in the foreground layer (mun_code) is also present in the ...
0
votes
1answer
169 views

How to create sequential numbers in a field by defining automatically the start, end and interval numbers?

I would like to create sequential numbers in a field called "virtual _Li". I have used the field calculator using def autoincrement() function and manually calculate the interval number. https://...
0
votes
2answers
336 views

QGIS expression filter

A QGIS expression (0<=0”az”<180) related to a column az with values 0 to 360 returns all records. Tried to_int and to_real as well because source of the data was a csv and result was same.
0
votes
1answer
319 views

model builder expressions code block and definitions

I am having difficulty wrapping my brain around the point of the expression vs the code block. What am I suppose to be defining? I copied the example from calculate value in the ArcGIS help website ...
0
votes
1answer
286 views

ArcGIS Online if-else in symbology expression

I'm trying to use ArcGIS online symbology expression with the if else statement. Code I’m using is: var dif1=$feature.Object var dif2=$feature.Unit var dif3=$feature.Object_1 var dif4=...
0
votes
1answer
252 views

QGIS format() function in expression Builder

Has anyone used the format() function in the expression builder? The definition states it require arguments. just playing around with it but cant find too much on this function so i am not sure on ...
0
votes
1answer
351 views

Using CON tool of ArcGIS Spatial Analyst?

I am doing a GIS project analyzing rooftops. I need to isolate North, Northwest, and Northeast facing rooftops. I've had success using the CON tool for other raster layers, but whenever I try to use ...
0
votes
1answer
248 views

QGIS Atlas Composer : Margin around feature not changing

I try to use an expression to set the margin around a feature in the atlas composer. In documentation, it's explained that it's better to be a double but a string or integer is accepted as an input. ...
0
votes
1answer
431 views

Rotating sld with expression?

I'm trying to rotate an arrow based on an attribute but the arrow is off by 90 degrees. Is there a method for doing a mathematical expression on the attribute within the sld? I've gone over the ...
0
votes
1answer
318 views

Atlas generation: get attributes of all features from the current view

I would like to show the attributes of every feature in the current view of the atlas. The background: On every page of the atlas is a map with some markers. The markers have got numbers and a text ...
0
votes
2answers
1k views

Calculating percentages in ArcGIS field calculator gives TypeError: 'float' object is not iterable?

I am trying to calculate the percent AREA in each class. I have created a new percentage field and have tried to populate it using the following equation in python in the calculate field tool. ...
0
votes
1answer
314 views

How to use SpatialOperator in filter expression in QGIS

In a python script I want to specify a request filter expression using a spatial operator. I am following the general syntax "field name" operator condition. For example: setFilterExpression('$...
0
votes
1answer
100 views

Problem with addιtion abstraction in Field Calculator

I want a bit analytical respond for the mistakes I have done in my code cause I am new to programming. I am using ArcGis 10.2. and I must process a field with distances in an attribute table I have. ...
0
votes
1answer
56 views

Calculating length of field using Arcade?

I have data with this format: 4024-457 and I need to separate the left and right portions from the '-'. The data is not always in that proportion (4 numbers left and 3 to the right) so I need to ...
0
votes
0answers
76 views

QGIS Value Relation filter

Let's say I have 3 layers: point layer (columns: id, group), table layer named materials (columns: point_id, mat_id), table layer named mat_list (columns group, mat_id). There is relation between ...
0
votes
1answer
150 views

Setting new value into field created by PyQGIS?

I'd like to create a new field named "vctcn93", loop the features of active layer, if string "metro" in feature name, I'd like to add a value string "get" into the field "vctcn93". But when I check ...
0
votes
1answer
286 views

Rule-based classifying (styling) by multiple fields in QGIS 2.18

I need to build an expression through which to achieve a rule-based classification by multiple fields. The basic expression could be: "Field 1" = 'Value a' AND "Field 2" = 'Value b' AND "Field 3" = '...
0
votes
1answer
35 views

Definition query on GDB annotation file- ArcGIS 10.3.1

I convert Cad annotation from Autocad, into GDB annotation using "import cad annotation" tool and this part of a big attribute table: The "TextString" is the field i need to present on my map, but ...
0
votes
1answer
471 views

Converting date field to string using ArcGIS Online?

I want to create a unique ID field for each row of data based on the created_date and OBJECTID. For example, if a sample of data had a created_date on 4/28/17 and an OBJECTID of 1, than I would want ...
0
votes
2answers
635 views

How to select data according to specific dates

I am using QGIS Essen version 2.14.1, and I am trying to select specific data according to dates in the field calculator: I am using the following formula but the system is telling me: syntax error, ...
0
votes
0answers
71 views

Clustered labeling in Mapinfo

I need to create a query where if a property with the same lotplan has the same address it is only displayed once. In case 1 we have the same lotplan and I want it to just show 32 once. In case 2 - ...
-1
votes
1answer
142 views

QGIS: Coloring a map relative to the values of certain attributes

I'd like to color the map using the "select by expression". I tried to use color_rgba(255, 0, 0, 255) for example. It only changes the color to be completely yellow which is the "selection color" in ...
-1
votes
1answer
123 views

Where Clause looking at two Columns and a RANGE Expression

Using ArcPy I'm Trying to Set up a Where Clause with a RANGE in my "FeatureClassToFeatureClass_conversion" This {Where Clause} needs to Query Two Columns in the data: FEATURE = 'ENVIRONMENT' and ...