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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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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131 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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2k views

How to copy values from field to another using arcpy?

Can some one please let me know how I can do simple field calculation like Copying From "A" to "B" in ArcPy? I have found lots os example on web which they all used extra expression and they were ...
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813 views

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
590 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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49 views

Remove decimal points from string field using field calculator

I have a string field populated with shape lengths in my attribute table but they have 12 decimal points. How do you remove decimal points from a string field populated with numbers using the field ...
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46 views

How to convert a “yyyy/mm” field to “yyyy/mm/dd”?

I am trying to edit an existing date field of the form "yyyy/mm" to a format that the TimeManager Plugin for QGIS can handle - I guess "yyyy/mm/dd" will do it. I've got as far as opening the ...
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86 views

Using ArcGIS Desktop field calculator (python) to parse date

I'm trying to parse a datetime field using python (but have never used python for it before). I have a field that contains a valid date, but not a valid time... and other fields that have valid hour ...
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72 views

QGIS field calculator returning results in different units?

I am trying to use QGIS to get the perimeter, area, bounds width, and bounds height of US congressional districts, using the US Census TIGER shapefile. I loaded the shapefile into QGIS, set my CRS to ...
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50 views

add text value to attributes

this is a novice question I have an attribute field that's missing a piece of information, i'd like to amend the attribute field like below: This is the current attribute field: "V:\Building & ...
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116 views

Field Calculator Script

I am looking to check how up-to-date a feature class is by using our latest parcel update. I am wanting to check "owner" field with "Owner_1"...I am using field calculator to grab the last name in ...
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256 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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388 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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189 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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485 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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175 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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168 views

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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1k 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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496 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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826 views

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

How do I append my field values in my .dbf to correspond with the values of my feature's attribute table. I need to append 0's to the field value if the field value is less than 11 characters in ...
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33 views

Conditional Statement in QGIS Field Calculator

I'm using QGIS to calculate total loss in an earthquack attack. I wrote this expression in Field Calculator. CASE WHEN "build_type" = 1 AND "MMI" < 5 THEN "perc_loss" = 0 WHEN ...
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63 views

Calculate area of geometry derived from current feature in QGIS 2.8

I'm trying to create a new field defined as the area of the convex hull of the current feature, in the Field Calculator in QGIS 2.8. Calculating the area of the current feature is easy ($area), and ...
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35 views

How to replace a directory using QGIS Field calculator?

I have a column called Hotlink full of incorrect directories and I need to edit them. They currently read C:/ABCD/filename.pdf and I want them to read C:/Maps/ABCD/ABCD/filename.pdf The script I'm ...
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40 views

QGIS - Field Calculator: scale_linear gives unexpected result

When I try to use scale_linear, its output isn't as I expected. My values are from 1 to 16, so I set domain_min = 1 and domain_max = 16. I want to interpolate to interval from 1 to 4 so I set ...
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363 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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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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124 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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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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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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987 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
486 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
1k views

calculate value using maximum value from different feature class

I'm trying to get the maximum numeric value from one feature class and use that value in an expression to calculate values of a different feature class. fc2.bldg_id = max(fc1.bldg_id)+1 Can this ...
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20 views

QGIS: Error message in query builder

I am using QGIS version 2.14.1 (Essen) and trying to update data in my table using field calculator. I am inputing the following statement: update "table_1" set "table_1" ='y' where "table_2" ...
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31 views

Auto-generated field in ArcSDE for end user

The objective: Create a process where a coworker can open an .MXD, start editing, add a feature to represent a complaint, then add records in a related table to represent an inspection. Along the way, ...
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40 views

Using Field Calculator vb to check for name with /n in the string?

I am calculating values for a field (Score) based upon the names from another field (Modified). One name is "blaugh\nblaugh". Field Calculator keeps treating the name as having a new line command. I ...
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1answer
189 views

Add comma to number labels, multiple records in attribute table

A QGIS question: How can I insert commas in 4 digit numbers in an attribute table that has multiple records, with some numbers that are only in the hundreds? It's for an animation so multiple labels ...
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244 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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372 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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234 views

Why do area measurements from “measure area” tool and field calculator differ?

My problem is when using the "measure Area" tool on the toolbar I get the correct value but when using the field calculator in the Layer Attributes the area is very different including -ve areas. ...
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Translating ArcGIS field calculator python expressions in to QGIS field calculator python expression?

I'm transitioning to QGIS from ArcGIS. I'm having trouble getting my python field calculator expressions to work in the QGIS advanced python field calculator. Here is a screenshot of the working ...
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28 views

How do I calculate average in my field calculator within specified limit?

I would like to calculate the average, max and min of each trips that I have. Each trips are also predefined (e.g. Trip 1, Trip 2) in the attribute table. (As below). I have more than 2000 trips. ...
3
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1answer
38 views

Help with Rastercalculator - Filter areas with a certain height difference

I'm struggeling a little bit with the rastercalculator tool of QGIS. At the moment I am working with a DSM and a DTM. My aim is to filter all wind turbines out of the DSM and replace it with the ...
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68 views

ArcGIS 10.0 Python script won't recognize null [duplicate]

Has anybody ran into in issue where Python field calculations and/or scripts won't properly query Null (None) values? The calculation I'm working on is a little more complex, but even the simple ...
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110 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 ...
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341 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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217 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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126 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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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 ...
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1answer
93 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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299 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 ...