[GIS] UpdateCursor ‘is not defined’ Python

arcpytableupdate

I have several files (shapefiles). Table 1 has only one row with several fields whereas Table 2 has several rows.
What I want is to take a value from Table 1 and populate all rows in Table 2. I used a SearchCursor to find the value I want and an UpdateCursor to populate the rows.

import arcpy

arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Ecodis_clip_split" 
#set workspace to folder with values

rows = arcpy.SearchCursor ("Table1.shp", "", "", "area_ha", "") 
#search for the value in attributetable

arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Split_wetlandt" 
#set workspace to folder with files which need to be updated

rows = UpdateCursor ("Table2.shp", "", "", "area_eco", "") 
#Update all rows of file with value from SearchCursor above

Running this, I keep getting this Errormessage:

Traceback (most recent call last):
File "<module1>", line 17, in <module>
NameError: name 'UpdateCursor' is not defined

If something is not defined, this means that Python sees it as a variable?
Even if I could get rid of the errormessage: would it populate all the rows in Table 2 with the value or do I need to do something else?
Note that I just started to learn Python and never scripted anything what so ever…

Edit 6/17/14 11:32 am

@ Aaron, would this replace the values in Table 2 with my searched values from table 1?

import arcpy
arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Ecodis_clip_split" 
#set workspace to folder with values

rows = arcpy.SearchCursor (table 1", "", "", "area_ha", "") 
#search for the value in attributetable

arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Split_wetlandt" 
#set workspace to folder with files which need to be updated

with arcpy.UpdateCursor (Table 2 ["area_eco"]) 
#Update all rows of file with value from SearchCursor above
for row in cursor:
    area_eco.replace(SearchCursor)

EDIT 6/27614 12:04pm

I updated my script to this.
Somehow it deleted my whole attributetable in Table 2 but I got it restored. I run it again and now nothing happens. It does not update the rows, the value in the rows stays 0.

import arcpy
arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Ecodis_clip_split" 
#set workspace to folder with values

rows = arcpy.SearchCursor ("Table1", "", "", "area_ha", "") 
#search for the value in attributetable

arcpy.env.workspace = "C:\\Users\\Documents\\Scoring\\Wetland" 
#set workspace to folder with files which need to be updated

rows = arcpy.UpdateCursor ("Table2", "", "", "area_ha", "")
del rows

Best Answer

You forgot to specify the arcpy module when calling UpdateCursor.

 rows = arcpy.UpdateCursor ("Table2.shp", "", "", "area_eco", "")

I second Aaron regarding using the with statement

Also, I would reference one of my OS answer regarding using either the "classic" cursor or the data access (da) one.

Finally, I would like to point you to a few resources to help you learn python/arcpy:

Hope it helps.

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[GIS] Using arcpy.UpdateCursor to delete rows does not delete based on counter

Following up with some of the comments to your post, I've cleaned up your script a bit. There are some unnecessary variables and the logic is a bit cumbersome. I obviously don't have the shapefile that you are working with and haven't tested this with anything locally so it may not work for you right off the bat, but it should at least give us a good basis to get you going.

import arcpy

shp = r'C:\Trash\Nov2011\ResFinalC6.shp'
sql = " \"PolyGUID\" <> ''"

rows = arcpy.SearchCursor(shp, sql)
delList = []
for row in rows:
    delList.append(row.PolyGUID)
print len(delList)
del rows

rows = arcpy.UpdateCursor(shp, "#", "#", "#", "FMEAS2 A")
for row in rows:
    if row.PolyGUID in delList:
        print "Deleting: %s %s" % (row.PolyGUID,row.FMEAS2)
        rows.deleteRow(row)
del rows

EDIT:

Okay, I think I have a better handle on your process. This is not the most efficient way to do it as it will create a cursor for every PolyGUID whether or not it has duplicate entries, but it's a start... NOTE: Changed second cursor to an update cursor (13:06 EST)

import arcpy

shp = r'C:\Trash\Nov2011\ResFinalC6.shp'
sql = " \"PolyGUID\" <> ''"

#--First, lets get a complete list of all PolyGUIDs
rows = arcpy.SearchCursor(shp, sql)
polyguids = set()
for row in rows:
    polyguids.add(row.PolyGUID)
del rows

print len(polyGUIDs)

#--Now, lets iterate over each PolyGUID...
for guid in polyguids:

    #-we create a new cursor for each PolyGUID that will only return rows for that GUID
    sql = " \"PolyGUID\" = '%s'" % guid
    rows = arcpy.UpdateCursor(shp, sql, "#", "#", "FMEAS2 A")
    x = 0
    for row in rows:
        if x == 0:
            #-ignore the first record (since sorted by 'FMEAS2', first record is the one we want)
            x += 1
        else:
            #-if multiple records with same PolyGUID, delete them
            print "Deleting: %s %s" % (row.PolyGUID,row.FMEAS2)
            rows.deleteRow(row)
    del rows

[GIS] SearchCursor() fails to read feature class

Confusingly, there are two different types of cursors: the "classic" cursors of Arc 10.0 and the arcpy.da cursors of Arc 10.1.

Arc 10.0 - "Classic" cursors

When using classic cursors (i.e. arcpy.SearchCursor) the cursor object is an iterable containing row objects. You need to use the getValue method to retrieve the data from the row.
The second parameter for arcpy.SearchCursor is your where clause, so you don't need the "*" parameter in there.
Your where clause is not set up properly, since Arc needs to have field names delimited by double quotes. To handle this with Python's use of quotes as string delimiters, you need to use the backslash escape character.

Here's a code sample with fixes applied:

fc = 'ShuttleStop_nextbus'
#List comprehension creates list of field names to read
fieldsList = [field.name for field in arcpy.ListFields("ShuttleStop_nextbus")]
cursor = arcpy.SearchCursor(fc, "\"NextBus_nu\" = '27837'")
for row in cursor:
    for field in fieldsList: #Iterate through field names
        print row.getValue(field) #Print value of this field for this row

Arc 10.1 - arcpy.da cursors

When using the new cursors in the data access module (i.e. arcpy.da.SearchCursor) you need to pass in a list of field names as the second parameter in the cursor constructor. This requires some more work up-front, but the resulting row objects are Python lists, which makes it easier to read data when iterating through cursor rows. arcpy.da.SearchCursor also has better performance than arcpy.SearchCursor, partially because it skips unimportant fields, especially geometry.
As before, your where clause is not set up properly, since Arc needs to have field names delimited by double quotes. To handle this with Python's use of quotes as string delimiters, you need to use the backslash escape character.

Here's a code sample with fixes applied:

fc = 'ShuttleStop_nextbus'
#List comprehension creates list of field names to read
fieldsList = [field.name for field in arcpy.ListFields("ShuttleStop_nextbus")]
cursor = arcpy.da.SearchCursor(fc, fieldsList , "\"NextBus_nu\" = '27837'")
for row in cursor:
    for cell in row: #Iterate through row, which is a Python list
        print cell #Print value of item in row list

Best Answer

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