Field calculators (available in QGIS, ArcGIS Desktop, etc) can recalculate the values of a single field on all, or selected, records within a table using an expression.

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QGIS Field Calculator Results Removed When Saving Edits

Mac OSX 10.6.8 QGIS 1.8.0 : Using the field calculator from the attribute table, the $area of each feature is shown nicely in the table until I try to save it, then all the values are replaced by NULL ...
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3answers
645 views

How to make Field Value constant size(length) by appending zeros towards the end?

I have been racking my brain, but I can't seem to find a solution to appending my field values in my .dbf to correspond with the values of my feature's attribute table. All I need to do is to append ...
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1answer
66 views

How to summarize a column in QGIS field calculator

I have data with a column containing a number value, and I want to divide the value of each feature by the total sum of all the values in the column (to get a percentage). So I would like to know if ...
3
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1answer
112 views

Accumulating values of date field using Python parser of ArcGIS Field Calculator?

I would like to modify the following accumulative/sequential python code sample in field calculator in a Date Time field. I think this is the correct code to use but let me know if not. The Date Time ...
3
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1answer
148 views

Calculating Percentiles in ArcMap?

I have a large polygon dataset (26,000) records with numerous attributes columns. I wish to calculate the percentile rank of each attribute. Say I have population_density in an attribute, is there a ...
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2answers
141 views

Iterate calculate field in multiple tables in ModelBuilder

I would like to iterate calculate field in multiple tables using ArcGIS Model Builder. The figure below explains details of the calculations. My existing model calculates value only for the first ...
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2answers
76 views

assign a number for each group in field calculator

I have several thousand features each of which has a name. The names are not unique. what I want to do with the field calculator is assign a number to each name so I can refer to a number and always ...
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3answers
884 views

How to Populate new field using expression containing MAX value from another field in ArcGIS attribute table using field calculator?

I've got one field X with 10 numerical attributes (float/double). I've created a new field Y (also float/double) which I need to populate with the percentage of each record/attribute (in each of the ...
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3answers
110 views

Field calculator problem

I have an issue withe the field calculator. It is impossible for me to multiplicate 2 columns (area * KZ). The result is always "0". I used the formula area * KZ....is this the right formula? LINK to ...
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1answer
1k views

Using the Field Calculator in a Domain field

I have a coded domain field with 10 dropdown options. Possible choices include integers and text. I need to change a selection of 250 features (which have differing values) to the same value. This ...
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1answer
1k views

How to use field calculator from QGIS Sextante plugin

I am trying to use the Sextante field calculator to calculate a field for a buffer radius using a categorical text field. The formula works fine when I run it using the standard QGIS field calculator ...
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3answers
808 views

ArcGIS Field Calculator Python numbering rows of fishnet

I have a grid of 100*100 cells. I want to add to each cell a number representing the row it is in (like in excel). I added a field and want try to solve that with field calculator: The code is ...
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1answer
439 views

Sum up area left “underneath” polygons in QGIS?

I have an area shape layer and multiple other area shape layers. Now I would like to calculate how much space (square kilometers or percentage of area) of the polygons of this area layer is NOT ...
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1answer
204 views

Calculate population coverage?

I am relatively new to QGIS and hope I explain this right. I am looking at the percentage of an population that has geographical access to healthcare. Therefore I have one shapefile with village ...
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0answers
53 views

Field Calculator convert text to integer then populate new field with sum [closed]

I have a .dbf with about 50 text fields containing numerals, I would like to convert those to integers and then sum them all in a new double field I created, is there an easy field calculation that ...
3
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1answer
159 views

How to calculate the intersected area from a layer with overlapping buffers in qgis

I need to calculate the area of landusetypes in 50m around various dots (all in one shapfile). My problem is, the buffers around the dots are overlapping each over in some places. I tried to ...
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0answers
217 views

How to calculate percentages using QGIS field calculator expression?

I am new to QGIS. I am wanting to calculate a field using other fields and some operators. Here is my expression: case When "RVM_CAT" = 'B' OR "RVM_CAT" = 'C' Then ("PC1" /100) * "RE_ha" When ...
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131 views

Warning 000405 when trying to calculate field [closed]

I am trying to create a model but am getting hung up on my first step. I need to calculate an ID field from an FID field so that I can join it to another table based on the ID field. So I have a ...
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1answer
96 views

How do I add a field to a table using the QGIS graphic modeler?

I was wondering if anyone could help as I'm struggling to get anything out of the QGIS graphic modeler. For info I have no programming skills whatsoever. I need to be able to add a new field to an ...
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0answers
84 views

Using Field Calculator to Convert Data Type In Field

I am trying to convert a field that is listed as "String" because it was imported into QGIS as a CSV (rural poverty population percentages by county in NC). I need to convert the percentages field ...
3
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1answer
76 views

Do pad functions of QGIS Field Calculator have bug?

I have this expression in the field calculator: regexp_replace('1', '^(\\d+)', rpad('\\1', 3, '0') ) gives 01 rather than 001 as expected. the *pad functions work fine when called outside ...
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0answers
295 views

Field calculator error [duplicate]

NOTE: This problem is similar to one that was answered here: Why does Field Calculator return 0 values when decimals are expected? I'm relatively new to python, and am trying to run a simple field ...
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4answers
134 views

Auto populate field with text using field calculator if/then

I've extracted values from a raster to a point file, but now I need a field with the text information from the raster attribute table that corresponds with the value. I've been trying to use the field ...
2
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3answers
1k views

Setting Zero values back to NULL

I'm working with ArcGIS 10.2 for Desktop and OS Windows 7. I need to set numeric vales from Zero back to NULL, but I can't from the field calculator. I'm working with a vector file and I need to ...
2
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3answers
2k views

Using if/elif/else statements in ArcGIS Field Calculator?

I have no experience with Field Calculator in ArcGIS 10. I have a very simple calculation I would like to perform that I could do easily via pure SQL but just can't seem to get my head around it in ...
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1answer
376 views

Why does this python function return a value of 0 in field calculator?

I am trying to calculate the percentage of a total which the median value makes. I have a column with the median column labelled (i.e. 1st,2nd,3rd,4th column is median), the columns of values and the ...
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2answers
109 views

How to handle “Error: Town not found” when updating an existing field with Field Calculator?

I want to update a field in field calculator. update existing field is checked. Column to be updated : Column2 CASE WHEN "COLUMN1" IS NOT NULL THEN "COLUMN2" = "Town" ELSE ...
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2answers
1k views

How to use the replace string function in Field Calculator?

Within an attribute table I'm trying to replace one string with another using the 'replace' function . As an example, there are a number of features whose field 'NAME' contain the string '(B)' and ...
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2answers
668 views

Why is QGIS Field calculator button greyed out?

I'm using QGIS to attempt to calculate the area enclosed by a set of points that I have capture used a GPS device. I have imported the coordinates from a CSV but when trying to open the field ...
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2answers
167 views

Increasing speed limit by 35 percent in ArcGIS Field Calculator?

I have a network with a speed limit attributes. I want to increase the speed limit by 35 percent in order to run an analysis for an ambulance. For example, if the speed limit is 60, I will ...
2
votes
2answers
1k views

FIeld calculator gives integer not a real as requested

Two fields "population" and "F06_popula" (both integers) were used in calculating a new field pct-diff. I asked that the new field be a decimal with a width of 10 and precision of 3. The result has ...
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5answers
275 views

Field Calculator expression to replace string only if it occurs

I have two fields (STREET1 & AKA_STREET_TEST1). I'm having a problem creating a simple IF THEN Python statement in the Field Calculator box. I've been searching the threads for a similar ...
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2answers
238 views

Updating column in Field Calculator using values of another column?

I am very new to GIS, so I hope to get some help. I am using ArcGIS 10.2 for Desktop. I want to create a new numeric column on my attribute table to store "seasons" in numbers. For example, I want ...
2
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1answer
244 views

ESRI File Geodatabase with a field calculator with an incrementing number

I've got a python script that runs on the Field Calculator of a ESRI File Database. Right now it runs correctly in that it will increment the last three digits of the value. But this is a script ...
2
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1answer
451 views

How to return absolute values using ArcMap field calculator?

I have a field of number ranging from -50 to 50. Is there a way using the ArcMap field calculator to populate a field with all of these standardised (positive numbers) so I have a range of 0 to 50 ...
2
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3answers
130 views

How do I normalize the values in a single Field (from a table) in ArcGIS?

First of all, this is my first post, and I would like to appreciate all the useful information I have found so far on this site. Second of all, I have encountered a problem, in Field Calculator. ...
2
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4answers
223 views

Field calculator Python else statement question

The codeblock below is run on Field1 and calculates Field1 to equal Field2 if they are not equal. Else it returns Field1. My question is, does the else statement actually recalculate Field1 to equal ...
2
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1answer
674 views

How to use Field Calculator to calculate area as percentage?

I am searching for python code to use in Field Calculator to calculate area as a percentage in relation to another field? The area percentage needs be calculated based on the total area for each ...
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3answers
956 views

Python and CalculateField

I am having trouble with using Python together with my gp.Calculatefield tool in my python script, and I am not sure why.. Heres the code (UPDATED) import arcgisscripting, os, sys myTempWorkspace = ...
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2answers
526 views

Looking for python/VB script to insert a new uniqe field

Is there any phyton/VB script which will add a field to shapefile which will be corresponding to first three characters from the shapefile name ? I am working in modelbuilder and arcgis 10. Thanks ...
2
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1answer
2k views

How to set the value of a field in all selected rows of a table using ArcGIS 10

I have an attribute table in ArcGIS (it's large - around 300,000 elements). I've selected some rows of the table using 'Select by attributes' and I want to set the value of a field for all of those ...
2
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2answers
171 views

Performing math in Python parser of ArcGIS field calculator?

I never used python but now I need a code to do this calculation: I'm doing this: math.atan(math.fabs( !Y2! - !Y1!)/math.fabs( !X2! - !X1!) )*(180/math.pi)
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2answers
73 views

How to convert negative field values to positive?

I have an xyz file that I want to convert negative field values in the z column to positive values. How do I do this with field calculator?
2
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2answers
132 views

Assign field values (double) based on values of other field (string) using field calculator

I want to assign numbers to a field, WScore (double), based on field values of Soils (string). They are in the same table of a raster. I'm not trying to add text to a double. What I want to do is ...
2
votes
2answers
431 views

How to replace “NULL” value with Zero in geodatabase table

I am having some difficulties to change "NULL" values to zero in geodatabase. I have tried the following python code in ArcGIS 10.1 ("Field Calculator") to change it but did not work. Pre-Logic ...
2
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1answer
284 views

Python Syntax Error when running Python Snippet of successful geoprocess

I am having an issue with a simple python snippet. Here's the background: I wanted to include an additional step in a nightly update script that replaces characters in a field that simply do not play ...
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1answer
360 views

How to get the First and Last Point coordinates of a Polyline with Field Calculator in ArcGIS10

I'm trying to get the First Point coordinates (x,y) and Final Point coordinates (x2,y2) from a polyline in ArcGIS 10 with the Field calculator. I've added 4 (double) fields like StartX,StartY,EndX ...
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2answers
138 views

Comparing 2 fields using Python

I am trying to compare 2 fields(double) using python. I want to round to the nearest 10th and flag those with a "1" that are not equal. Here is what I have at the moment: def Qcontrol(old, new): ...
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1answer
142 views

Field Calculator: return two or more field value

I trying to return three field values in same If Statment and conecate them, but i Get NULL value insted of the conecated fields getClass (!InDiameter! , !OutDiameter! , !TheridDiameter!, ...
2
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1answer
58 views

How can I change all the entries in a field to be entirely lower case?

I have a field with a bunch of species names, but for a single species there a bunch of case combinations (e.g. Cat, CAT,cat). I want to make a new field which has all the entries in all lower case. I ...