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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Simple field calculator equation in ArcGIS 10 not working

I'm new to ArcGIS 10 and am trying to do a really simple field calculator equation and it is not working. I'm just trying to find the percentage of a certain demographic trait by doing: ...
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2k views

Calculating X and Y of line start and line end using ArcPy?

I have a series of polyline shapefiles and I am trying to automate the process of calculating the X and Y coordinates of the line start and line end using Python. I have added the 4 fields (startx, ...
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How I can reverse numbers in a string without reversing any text? [closed]

I have a string, I need to reverse just the numbers in the string without the text: String: [321 test] The result will be: [123 test]
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601 views

Round decimal number in ArcGIS10.1

How can I round the decimal number in a table in Arcmap: e.g. how can I set it to 2.60?
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217 views

ArcGIS 10.1 : Returning shape.area in my code block

I try to calculate a field using an 'if' statement in the field calculator. Here is my code : " #Expression MyField_2 = def Reclass(!MyField_1!) #Parser Python 9.3 #Code Block def ...
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172 views

Problem using field calculator to add numbers in new field with preceding zeros

I wish to add a field in an attribute table that should work as a georeferencing key. It needs to take into consideration values from a series of fields. The last field is a housenumber and it ...
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1k views

Forcing decimal numbers to use comma in ArcGIS Field Calculator?

Can I add the comma "," to force the decimals to remove from the attribute and replace with the number? For example, I have an Acres field column that says 506320.0750 and I want to replace the ...
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What expressions for QGIS field-calculator?

I do not understand what language I have to use in field-calculator and labels on QGIS: SQL or Python? And where I can find the possible script/expressions to use? in the image you can see the ...
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234 views

Count the number of characters in a field (Python)

I have a field that contains street names and a second field called COUNT. I need to perform a Python field calculation on the COUNT field that counts the number of characters in the STREET_NAME ...
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136 views

Using Field Calculator to append attribute

I have a field containing the file names for photos. I need to add the folder location to the beginning of each file name. Anyone know the code for doing this in Field Calculator?
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Calculate Field Syntax: If statement over many fields

Apologies if this has already being asked but I couldn't find a page pointing to this problem. I'm struggling with the python syntax in the Calculate Field so that, in the table above: if b, c, d, ...
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How to count occurrences of one field grouped by values of another?

Is there a way of calculating the number of unique text strings in a field in ArcGIS 10.1? I have a number of repeated strings in this field, but would like to calculate the number of unique strings ...
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Use output of Add Field as input for Calculate Field in ModelBuilder

I have created a simple model in ArcGIS 10 which, after some initial processing of a feature class, outputs outputfc and adds a field to it. Regardless of the feature class input (which the user ...
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Calculate field using variables as fields

When I calculate a field like this: field_0="field_name0" arcpy.CalculateField_management("Layer", field_0, '!field_name1! / !field_name2!', "PYTHON_9.3") It works! The field "field_name0" in the ...
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Why does Field Calculator return 0 values when decimals are expected?

I realize I posed this question, and got answers, several days ago (see (Field calculator error)) , but none seem to really be working, and so am posing again. Below are two screenshots that show the ...
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Using Python to Calculate a field

I am trying to replace values in a single column using an else if statement, but I keep getting an Syntax error in line 2. I'm new to Python so it's probably an easy solution, but I haven't been able ...
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6k views

Using conditional statements in Field Calculator

I have two fields, "P_Area" and "PC_Area", whose sizes I'd like to compare in a third field, "Areas_Equal". The "Areas_Equal" field should contain a "Yes" if the other two are equal and a "No" if they ...
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322 views

Adding an “m” to the end of every number in a row

What function do i need to use to add an space and an m after every item in a row, using the field calculator in the attributes table. I have a load of numbers (as strings) and would like to add m ...
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410 views

Using Python in Field Calculator to compare two fields

I'm trying to use field calculator to compare two fields in a table of tax parcel data, Land Value (LAND_VAL) and Improvement Value (IMPRVT_VAL). My goal is to determine (1) Parcels with land value ...
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985 views

Auto-calculate field (area or formula)

I'm wondering if anyone has any insight into the potential to auto-calculate the value of a field, either area or distance (ideally) or a formula (based on the values of say 2 other fields, or an ...
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480 views

Python find string with two decimal characters

I have two columns in a personal geodatabase table that I'm trying to add up (to a third field) using a python function in field calculator, however some of the string values are not real numbers. ...
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Why is ICalculator.Calculate significantly slower than the CalculateField geoprocessing tool with SDE datasets?

I just discovered today that there are essentially two ways to calculate field values in ArcObjects: 1. Using ESRI.ArcGIS.GeodatabaseUI.ICalculator: ITable table = …; ICursor updateCursor = ...
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How to count and record the number of entities with the same name in the field calculator?

I have a question with ArcGIS 9.2. In an attribute table the column [name] includes the name of every place in this layer. Next to that (in columns [numbers]) there should be recorded how often a ...
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Field Calculator in ArcGIS - keep equation

I'm using Arc 9.3.1 (Arc Editor). In edit mode I've created a simple field calculation. For example's sake let's make it [Field3] = [Field1] + [Field2] How do I 'keep' the calculation so Field3 ...
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How to pad field with blank spaces using calculate field tool of ArcMap?

I am trying to pad the right side of a field with blank spaces so that when I label the field, it labels further over to the left. The only way that I can seem to make this work so far is by adding a ...
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116 views

Calculating file name with field calculator

Is it possible to calculate the file name in an attribute table? My shape file has a name like "cities.shp". In this shape file I want to have a attribute "cities").
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108 views

Calculate average value for each row

The picture is an example, but the method would be the same at mine bigger dataset. So i have some parcels with each a ID value and some fields. such as field 1, field 2, field 3, fieldd 4,... with ...
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118 views

How To Determine Percent of Matched Data?

In my attribute table, I have 2 columns with qualitative (categorical) data. Both of them are from different sources so I am trying to find the percent of matched data from these 2 columns. I created ...
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103 views

How to find lowest value that is not null using Python in ArcGIS for Desktop?

I have four fields in my table, (A,B,C,D). The field type is double with some fields being NULL. I used min(A,B,C,D) to return the smallest value and it works well if there are no NULL value in any of ...
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579 views

If-Then Statement in Field Calculator

Scenario: I have four fields: A, B, C and D Field A is text-based and contains values from '000' up to some number 'xxx' Field B contains a set of values (also text, but represented by numbers) ...
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basic problem using division in field calculator

This is a very basic question, but I can't figure out what's going on. I've got election results I'd like to simply display as percentages rather than vote totals, which should be as simple as ...
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76 views

Averaging XY data for locations in QGIS

I wanted to find out mean of the selected point using QGIS. I tried out selecting using attribute table but could not find an option for mean in field calculator. I have attached a screenshot with ...
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QGIS - Is it possible to increase Output Field Name?

When creating a new Column, the default value for the length of the name is 10. Using the Field Calculator via the Model Builder, I want to include the names of regional areas into the columns which ...
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How to use the field calculator's centroid() Geometry function in qgis 2.0?

There is an option in the field calculator for centroids under geometry which when you double click gives you "centroid( ". What information is required here in order to use this function?
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Adding VBA into a Python script generated by ModelBuilder

I have created a model that does a calculate field and have used VBA in the code block. But when I export it to Python, it doesn't work. Here is the VBA code: new_value = ...
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Expression to calculate and sort data from several layers into one layer

I am trying to develop an expression whereby one layer can add data from 2 other layers and then rank them, is this possible? I have also tried the problem with using just 1 layer but I cannot work ...
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How to create button that calculates acres on selected polygon features?

I'm looking to create a simple button that calculates acres on selected polygons and can't quite find what I'm looking for. I read through this thread: automating a python script..., but found it ...
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1answer
413 views

Measurement units not returned in project CRS units

I am attempting to calculate area of country polygons using the field calculator. The layer in question is unprojected WGS84, but I have set the project CRS to World Equidistant Cylindrical ...
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Joined tables and now field calulator is greyed out

In ArcMap (10.2), I accidentally calculated the wrong field outside of an edit session, so there was no way to reverse my action. I restored a previous version (shadow copy) and joined the tables ...
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1answer
139 views

Using arcpy and script toolbox to add the date to a attribute table

I would like some information on how to add a date to an attribute table, by adding a user specified date in a script tool that will update the polygons attribute table. In short I have two polygons ...
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1answer
99 views

Trouble calculating areas in QGIS using field calculator

I am testing various projections to calculate areas using ICES statistical shapefiles and the QGIS field calculator. I am using ICES areas downloadable from the following link: ...
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1answer
194 views

Why is this field calculator expression evaluated incorrectly when using Python syntax?

I have a polygon featureclass containing an integer field 'gridcode'. I've added 2 new float fields VB_calc and Python_calc, both of which should be equal to gridcode / 1,000,000. If I calculate the ...
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82 views

How to find and replace a singe word in a string?

How do i find and replace a single word of a string? e.g. Calle Iparraguirre to Iparraguirre I've tried: replace( 'Calle\\s', 'Calle\\s', '') replace( "name",'calle','') and all combinations ...
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ArcGIS 10 Field Calculator [closed]

I'm new to GIS in general and field calculator in particular. I have a basic attribute table with three columns. I'd like to assign values to column C based on what is in column A. If Column A = 8 ...
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1answer
114 views

Field calculator uses wrong fields when working with joined data

I am having an issue in qgis table joins. i have a joined a csv file to a sqlite database and common id is used for join. the join is displays correctly in attribute table. the attributes in sqlite ...
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813 views

Calculate Field python code has “Expected end of statement” error

I am creating a line shapefile from a csv in a Python (2.7) script. I am assigning an ID field from the csv to a variable and then later using it in the Calculate Field tool. The ID field originally ...
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406 views

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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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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56 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 ...
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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 ...