topic Re: Get Field Value in Python Questions

Get Field Value

yanaybrook1 — Wed, 25 Jul 2012 08:04:55 GMT

hello,
Im trying to find/write a simple code line that will get the value from a
specific row and columm (field name). - I only have one table.
I cant use the modelbuilder tool (GetFieldValue) because i need it in python..

thx!

Re: Get Field Value

ChristopherThompson — Sat, 11 Dec 2021 20:20:30 GMT

Look into Search Cursors (arcpy.SearchCursor or the new arcpy.da.SearchCursor if you're at 10.1). These allow you to create an object containing the rows of a given table (spatial or otherwise) and step through that object row by row. If you have a specific row or set of values in a feature class you can create a search cursor based on a sql query.

For example, if you had a feature class with a classification of things in a field named 'class' and you needed to extract all the values held in a field named 'Data' for records with a class = 1 you might do something like this:

things = arcpy.SearchCursor(yourFeatureClass, """ 'class' = "1" """,'','Data')
for thing in things:
   mydata = thing.Data
   ...code to do something with the mydata value, such as writing it to a text file, etc..

There may be other ways to approach this if you're looking for one value from a single row, but usually we want to deal with many rows in the same way, perhaps conditionally based on the the value held in a field. Hope this helps.

Re: Get Field Value

DeeptiPuri — Thu, 18 Oct 2012 16:58:41 GMT

Hi There

I want to read a value from one column (result of calculate UTM tool) and it is same for all the points (most likely there will be only one point). I can use searchcursor in arcpy. But is there any simple way similar to GetFieldValue for arcpy?
Thanks

Re: Get Field Value

JillianPenney — Thu, 18 Oct 2012 23:01:34 GMT

This sample code may help if you want all the values in a column, or if you want a specific value using getValue in a search cursor.

[HTML]
import arcpy

SC = arcpy.SearchCursor(r'C:\Data\TestData.gdb\Roads')
field_name = 'Object ID'
for row in SC:
    # if you want all values in the field
    print row.getValue(field_name)

    # you can also get specific values
    if row.getValue(field_name) == 5
        x = row.getValue(field_name)
        # using break allows you to stop the search cursor
        break

del row, SC
print x

[/HTML]

Re: Get Field Value

RobertPotter — Sat, 11 Dec 2021 20:20:32 GMT

Hi,

I am having this issue that the row.getValue(field.name) breaks my script

rows = arcpy.SearchCursor(DBase_file)    
for row in rows: 
    for field in desc.fields:
            rVal = row.getValue(field.name)
            arcpy.AddMessage("Field Name: " + field.Name + "Value: " + rVal)

In the examples above you have a haed coded field name but I am looping through unknown field names and it just stops at the rVal=... line.

Any ideas??

Re: Get Field Value

T__WayneWhitley — Fri, 17 May 2013 07:11:33 GMT

I question your use of desc.fields...
Not sure that describe object is iterable. Can't you use the listFields function instead? Careful with case, could be ListFields, look up the topic of listing data.

Re: Get Field Value

ArkadiuszMatoszka — Sat, 11 Dec 2021 20:20:35 GMT

I question your use of desc.fields...
Not sure that describe object is iterable. Can't you use the listFields function instead? Careful with case, could be ListFields, look up the topic of listing data.

Hi,
As Wayne told, use arcpy.ListFields instead of desc.fields, also you should change AddMessage statement a bit, to make sure it won't crush if field type is different than TEXT:

fields = arcpy.ListFields(DBase_file)
rows = arcpy.SearchCursor(DBase_file)    
for row in rows: 
    for field in fields:
            rVal = row.getValue(field)
            arcpy.AddMessage("Field Name: " + field + "Value: " + str(rVal)) # is not always string

Regards
Arek

Re: Get Field Value

ZdeněkSoldán — Sat, 11 Dec 2021 20:20:38 GMT

Hello,

I have a similar problem. I have a searchCursor that goes through a specific column in a table. On every row I need to compare the value from this row with the value on the next row and if they are equal do something and if they aren't equal do something else.

mxd = arcpy.mapping.MapDocument("CURRENT")
table = arcpy.mapping.ListTableViews(mxd)[0]
column = "name"
cursor=arcpy.SearchCursor(table)
for row in cursor:
    print(row.getValue(column))

I have this sample of code. It goes through all rows. But how can I compare the value from row[row] with the value from row[row+1]??

Thanks for any help.

Re: Get Field Value

RebeccaStrauch__GISP — Wed, 27 Jul 2016 15:15:32 GMT

I see you started a new question, which I would have suggested too. For others...

Compare value from n and n+1 row in searchCursor