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I need to change values in field "name1" (string field) in specific rows: 70-72 into "no land use" value. I search Arcpy code to do it.

i red How to select specific row in attribute table using ArcPy (without iterating through whole table)? but didn't understand what shoud i do.

I using this code:

import arcpy

lyrName = r"G:\PROJECTS\herzel138\gis\layers\New File Geodatabase.gdb\digum2"
with arcpy.da.UpdateCursor(lyrName, ["name1"]) as cursor:
    for row in cursor:
        if row == 70 and row ==71 and row ==72:
            row[0] = 'no land use'
            cursor.updateRow(row)
            print "Processing complete"
        else:
            print 'nothing founded'

enter image description here

but i get no result:

enter image description here

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  • name1 field type text Commented Jan 4, 2018 at 9:10

2 Answers 2

Reset to default
3

You must check the value of the OBJECTID field, not the row object:

import arcpy

lyrName = r"G:\PROJECTS\herzel138\gis\layers\New File Geodatabase.gdb\digum2"
with arcpy.da.UpdateCursor(lyrName, ["name1", "OID@"]) as cursor:
    for row in cursor:
        if row[1] in (70, 71, 72):
            row[0] = 'no land use'
            cursor.updateRow(row)
            print """Updated row {}""".format(row[1])

The OID@ token refers to the OBJECTID field, no matter how it's called (this may vary depending on the dataset format - file gdb, shapefile, enterprise gdb...). See the arcpy.da.UpdateCursor help page for reference.

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2

As a complement to the answer provided you dont need to iterate over every row in the table. In your case you could specify a where_clause in the cursor to only iterate over OIDs 70-72 and then update them without an if statement.

import arcpy
lyrName = r"G:\PROJECTS\herzel138\gis\layers\New File Geodatabase.gdb\digum2"
sql = """{0} IN (70,71,72)""".format(arcpy.Describe(lyrName).OIDFieldName)
with arcpy.da.UpdateCursor(in_table=lyrName, field_names='name1', where_clause=sql) as cursor:
    for row in cursor:
        row[0]='no land use'
        cursor.updateRow(row)
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3
  • This is indeed more efficient/elegant :) But unless there are at least 100 000s of rows the performance gain will not be noticeable I think Commented Jan 4, 2018 at 9:34
  • I agree, I usually dont bother using a where_clause since the cursor is so fast anyway Commented Jan 4, 2018 at 9:36
  • 1
    If there is an index on 1000 or more rows, where_clause use will always be noticeably faster. Constraining the query to return only the required rows is always best practice. Commented Jan 4, 2018 at 13:55

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