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.

learn more… | top users | synonyms (1)

22
votes
2answers
35k views

How to calculate polygon areas in QGIS?

Hi I would like to simply calculate areas of a area-shape file in square meters or in acres (ha). I didn't find that functionality in the vector tools. Could anyone here help me with that?
15
votes
6answers
6k views

ArcMap 10.0 Python Field Calculator, Find/Replace Double Quotes

I'm trying to use the Field Calculator (ArcMap (10)) to strip out double quotes in an address field (I didn't put them in there, believe me). I've tried many incantations but am still unable to even ...
10
votes
2answers
1k views

How to compute a new attribute based on changes in another attribute?

I am attempting to classify a set of gps time-encoded point data into behaviors based on different attributes. I have created an attribute that is 0 for home and 1 for away based on location, and now ...
9
votes
3answers
5k views

How to round a column in attribute table (ArcMap)

I want to use the Field Calculator in ArcMap to round an existing column to two decimals. Currently I have a column that is 6 decimal places long and would like to simply round it down to 2 decimals. ...
9
votes
8answers
11k views

How to Remove return/newline (\n) character from Field using Python and Field Calculator?

I have a geodatabase table with a field that I'm trying to remove return characters (new line). I found this post (How can I remove (chomp) a newline in Python?) of how to do it, however it is not ...
9
votes
2answers
1k views

How to get latitude /longitude in Degree Minute Second (DMS) using QGIS field calculator?

I have come up with the following expression to convert 5.1234 to 5° 7`24.24" toint ($x) || '° ' || toint((($x) - toint ($x)) * 60) ||'`' || substr( (tostring(((($x) - toint ($x)) * 60) - ...
8
votes
5answers
4k views

Is there a way to concatenate fields in field calculator of QGIS?

Is there a way to concatenate fields in field calculator of QGIS? (e.g. hectares + ' ha')
8
votes
5answers
382 views

Print out the properties of the attribute table in qgis?

I have to merge a lot of shapefiles into one great shapefile. So I want to compare the properties of the attribute tables to see if there are differences between the tableproperties of each shape ...
8
votes
1answer
7k views

How to perform If Statement in Field Calculator of ArcGIS for Desktop?

I have a shapefile containing two numeric fields ("Dist_1" and "Dist_2"). I want a Field Calculation that will populate an additional field ("Result") with one of three answers: First if Dist_1 is ...
8
votes
2answers
296 views

How to refer to another layer in the field calculator?

Is there a way to select an attribute from a polygon layer and insert the value into a virtual field of a point layer using "within" in the field calculator? CASE WHEN within($geometry, ...
8
votes
3answers
1k views

python script error- with GetParameterAsText [duplicate]

I have a seemingly simple code which iterates through a list of feature classes and calculates an ID field in the attribute table that is equal to the first 5 characters of feature class name. The ...
8
votes
2answers
4k views

Converting from DMS to DD using Python in Field Calculator?

I need to convert lat/long that is expressed as degrees, minutes, and seconds in the data into decimal degrees. For example, in the data, they are listed as N335042.06 in the Latitude column, and ...
8
votes
1answer
141 views

Can you use wildcards for column headers in Field Calculator?

I know you can use wildcards for fields like so (in the Field Calculator): case when "column" ILIKE '%example%' then 1 else 0 end Can you do something similar for the column headers themselves? I ...
7
votes
2answers
5k views

Troubleshooting ERROR 000989 Python syntax error from ArcGIS Field Calculator?

I'm trying to used the Python syntax in ArcGIS 10's field calculator and am thoroughly confused. So far the most basic calculations are failing me, and I don't understand why. I'm trying to create a ...
7
votes
4answers
3k views

How to remove numeric characters from alphanumeric value in field calculation?

I have a field containing alphanumeric values in the following format: A-AA00 Sometimes they are also A-AAA0 I need a Python script I can put in the field calculator in ArcMap 10 that will at ...
7
votes
2answers
2k views

How to calculate perimeter of polygons in Quantum GIS?

Is there a way to calculate perimeter of polygons with the field calculator of qgis, like there is for area calculation?
7
votes
2answers
310 views

How to find if polygon has a hole using field calculator in ArcGIS

Some 3rd party software cannot handle polygons with holes (donut polygons). To find them I always use ArcView 3 field calculator, because: however when I try to do this in ArcGIS, I get this: So ...
7
votes
1answer
1k views

Meaning of exclamation mark in Python parser of ArcGIS Field Calculator?

In the following line, I don't understand what those exclamation marks mean? And why put everything in quotation? I don't understand the purpose of the variable expression, please explain to me as I'm ...
7
votes
3answers
3k views

Calculating Field based on name of shapefile

I have multiple shapefiles to which I have added a field called "gname1". For each shapefile, I want "gname1" to be set to the name of that particular shapefile, for every feature within the ...
7
votes
3answers
3k views

How to replace non-English characters in attribute tables using Python?

I have a few shapefiles where some of the attributes contain the non-English characters ÅÄÖ. Since some queries doesn't work with these characters (specifically ChangeDetector), I tried to change them ...
6
votes
4answers
5k views

Field Calculation - Python - If/Then over multiple data columns

I have some VB code saved that looks at two columns of data, and populates a third with the low value. Pre-logic Script Code: Dim output as double if [MIN_LEFT] < [MIN_RIGHT] Then output = ...
6
votes
3answers
18k views

Basic If/Then in ArcGIS 10.2 Field Calculator (Python or VB)

I've been looking through these threads and can't seem to figure out my answer yet. Very new to VBA and Python, but lots of years with Arc.I know I can do this the slow way with Select By Attributes, ...
6
votes
1answer
130 views

How to remove comma from combined fields which should be null?

I have Drivers License as one field and State as the other and there are to be combined and formatted as Drivers License, State. How do I handle records that do not have either a Drivers License or ...
6
votes
1answer
6k views

Calculate area within Python script in Arcmap

I am trying to calculate the area of a polygon within my Python script. I create a new polygon from merging two together, and I'd like to add the area of the resulting polygon to a field in the output ...
6
votes
2answers
403 views

How to delete last part of a string starting from the 1st non numeric character? [closed]

I'm looking for a Python or VB statement to remove the last part of a string, starting where the 1st non Numeric character appears, using the Field Calculator in ArcMap 10. Here's an example of what ...
6
votes
5answers
10k views

How do you test for a NULL string field in the Field Calculator with Python?

I am trying to perform an operation on a string field with a condition that it contains data. Referencing None with Python does not appear to work when the field is nullable and contains <Null> ...
6
votes
2answers
4k views

Using Field Calculator in QGIS to update columns with centroid coordinates

In QGIS I would like to update two columns with the centroid easting and northing of my polygons. I am using the field calculator. I have tried using $x and $y but this only seems to work for points. ...
6
votes
1answer
4k views

How to measure area correctly?

I have now used my entire evening, but I can't figure out how to make areal calculations (eg. in km2). I have tried the 'field calculator', I have tried the 'measure area' function on the "attributes" ...
6
votes
3answers
712 views

Random value calculation in QGIS

Is there a way to do a random value calculation within a range in QGIS? I have been able to do this within ArcMap Field Calculator with the following code: Dim max, min max=20 min=5 ...
6
votes
1answer
2k views

Get shape filename in attribute field using field calculator

I apologize for crossposting against the ESRI geoprocessing forum, but it seems like this one gets answers. I'd like to have a modified append tool (ArcToolbox) that takes multiple shapefiles with ...
6
votes
1answer
308 views

How to classify time periods in a new field, using Python?

I have a datetime field (Horario) in my feature class, showing only the time. Although the date doesn't appear, it seem to be stored automatically as 30 Dec 1899, I'm not sure why. I want to use ...
6
votes
1answer
3k views

Syntax of conditional statements in QGIS Field Calculator(s)

I have a shapefile which I need to modify. There is one column "CLASS" with the attributes: "A", "B" and "C". I need to change "A" into "1!, "B" into "2" and "C" into "3". I tried it with case when ...
6
votes
1answer
1k views

Editing tables using SQL in ArcMap

We've recently started working with ArcMap, having used MapInfo previously. I've created a shapefile in ArcCatalog and want to update some columns using SQL. In MapInfo I'd write the following command ...
6
votes
1answer
3k views

ArcMap Field Calculator syntax (again)

I'm trying to string together a field calculator script that will populate all the records of a field at once based upon values in a number of fields. I can't even get the first part of the command ...
6
votes
1answer
203 views

Calculating a Unique ID on a Subgroup of Polygons

I would like to assign a unique ID to polygons in a dataset. The catch to my issue is that I would like polygons that fall within a polygon to have the same unique ID. My example is related to ...
5
votes
2answers
2k views

Arc 10 field calculator scripts

I need scripts for the field calculator that: extracts the first word from a column, i.e. "Jones School" - "Jones", and A script that will capitalize this new field, "Jones" - "JONES". This is Arc ...
5
votes
1answer
3k views

How to fill my column with consecutive numbers

I m very new to Qgis, so forgive this simple question. Searching in older topics didn t help either.So: I make a new column in my attribute table and it has a default value(for example 0). I want to ...
5
votes
3answers
2k views

calculating a field in which null values may be present

I would like to calculate a field (short integer) using other fields (short integer) present in the table. In some cases these fields may have null values for one or more of the fields. For example, ...
5
votes
2answers
1k views

How to find wildcard string using Field Calculator script code?

I'm trying to find part of a text string in the CLASS_NAME field and return a text string to the Abrv_Name field using the Field Calculator in ArcGIS 10 via a Python parser. Here is what I have tried ...
5
votes
1answer
3k views

Python If else statements

I'm trying to populate a field from another. The catch is that it isn't 1 or 2 values. If my field A = 4 then I want it to return field B to 0. But if Field A is 1, 2 or 3 then I want the user to be ...
5
votes
1answer
450 views

Translate Excel formula to be used in field calculator

I have a series of equations to create corner points to make rotated polygons based on angles in the attribute table, but I have created it in excel and can't figure out the syntax to get it to work ...
5
votes
2answers
265 views

Calculating Quarter (Q1, Q2, etc) using Date field in ArcMap Field Calculator?

I am using ArcMap 10.0 and making a map where I symbolize on annual quarter (i.e. Q1 2013, Q2 2013, and so on by quarter through 2015). If a date field contains this: 01/15/2013, and I wanted to ...
5
votes
5answers
3k views

How can one execute an SQL script in field calculator in ArcGIS 10?

I am trying to transfer over row data from a table to columns in a shapefile table. There is a common "SA" variable between the two (i.e. the study area number) but there is more than one land use ...
5
votes
5answers
588 views

How to create a label formatted like “ 1,000' ” from a numeric field?

This question builds on a previous question I came across at gis.stackexchange: How to easily edit attribute data using Regular Expressions? Perhaps someone can point me in the right direction? I ...
5
votes
2answers
1k views

How to add a sequence to the attribute table?

Is there a way to use the field calculator in QGIS to create a range of values in a count sequence with a specified input range? For example, if I wanted to have the values 1 to 5 repeated within my ...
5
votes
3answers
6k views

ArcGIS 10 Python split string

I am trying to use Python to split a string field into three new fields at the separator " - ". The field is in the format "a - b - c". So I initially had this in the field calculator for newFieldA: ...
5
votes
2answers
107 views

How to calculate with time values in QGIS?

I have two string fields in a vector layer, "From" and "To", with values in the format of 10:16:30 and 10:18:00 e.g. I would like to calculate the difference in minutes as a decimal value, in this ...
5
votes
4answers
927 views

How do I fill in serial letters (AA, AB,AC…,BA,BB,BC…ZZ) to a shape?

(I am using ArcGIS software, ArcMap...) MY PROBLEM I have a shape file containing points. The shape file contains 3 columns named FID, Shape* and Label. In the column I want to fill in AA, AB, ...
5
votes
1answer
176 views

How do I extract partial data from one field to another?

Answer Below I am attempting to extract a date stamp that is contained in one field and insert it into another field. The issue is that the date (in bold below) is not in the same location in each ...
5
votes
2answers
216 views

Field calculator script to work out first 5 dominant area fields?

I have 5 fields of different landcover types with areas of each and found below: > PRC_Water| PRC_Bare| PRC_Urban| PRC_LVeg| PRC_LVeg| > 5 20 40 20 15 I have ...