topic Replace Null values with 0 in many fields in Python Questions

Replace Null values with 0 in many fields

JAKERODEL — Wed, 02 Mar 2016 18:10:48 GMT

Can somebody point out what I am doing wrong here? I am trying to get a list of fields (PrecipFields) and replace all null values with 0. When I call out a specific field it works fine. When I use list of fields it looks as if it runs but non of the values are updated.

>>> with arcpy.da.UpdateCursor("asciiPoints",["ippt_allsites_spas1325_024_19230927_0700_UTC"]) as cursor:

... for row in cursor:

... if row[0] == None:

... row[0] = 0

... cursor.updateRow(row)

Works fine...

My field list I want to use...

>>> print PrecipFields

[u'ippt_allsites_spas1325_021_19230927_0400_UTC', u'ippt_allsites_spas1325_022_19230927_0500_UTC', u'ippt_allsites_spas1325_023_19230927_0600_UTC', u'ippt_allsites_spas1325_024_19230927_0700_UTC', u'ippt_allsites_spas1325_025_19230927_0800_UTC', u'ippt_allsites_spas1325_026_19230927_0900_UTC', u'ippt_allsites_spas1325_027_19230927_1000_UTC', u'ippt_allsites_spas1325_028_19230927_1100_UTC'

This is a shortened list. There could be hundreds of fields.

Nothing happens...

>>> with arcpy.da.UpdateCursor("asciiPoints","PrecipFields") as cursor:

... for row in cursor:

... if row[0] == None:

... row[0] = 0

... cursor.updateRow(row)

...

Re: Replace Null values with 0 in many fields

DarrenWiens2 — Wed, 02 Mar 2016 18:12:59 GMT

Remove the quotes around "PrecipFields". Quotes mean text/string. No quotes means variable, in your case, a list of field names.

Re: Replace Null values with 0 in many fields

JAKERODEL — Wed, 02 Mar 2016 18:16:36 GMT

That doesn't work for me either. No error just nothing happens.

Re: Replace Null values with 0 in many fields

DarrenWiens2 — Wed, 02 Mar 2016 18:20:42 GMT

You'll also have to loop through the fields in your field list. row[0] means look at the first field only.

Re: Replace Null values with 0 in many fields

JAKERODEL — Wed, 02 Mar 2016 18:45:54 GMT

This would do that right? Same result...

>>> with arcpy.da.UpdateCursor("asciiPoints",PrecipFields) as cursor:

... for row in cursor:

... for field in PrecipFields:

... if row[0] == None:

... row[0] = 0

... cursor.updateRow(row)

Also tried this...

>>> i = 0

>>> with arcpy.da.UpdateCursor("asciiPoints",PrecipFields) as cursor:

... for row in cursor:

... if row == None:

... row = 0

... cursor.updateRow(row)

... i += 1

Re: Replace Null values with 0 in many fields

RuthBowers — Wed, 02 Mar 2016 18:49:01 GMT

Hi, Jake. You have to enumerate through all the fields. As Darren pointed out, row[0] refers to the first column in the row. I pasted in an example below. When you use enumerate, using my example, i is the number of the column position from the left (of the columns included in the cursor), starting at 0. c is the corresponding value from the list being enumerated through, in your case, the column name.

# Assuming PrecipFields is a python list of column names.

with arcpy.da.UpdateCursor("asciiPoints", PrecipFields) as cursor:

for row in cursor:

updated = False

for i, c in enumerate(PrecipFields):

if row == None:

row = 0

updated = True

if updated == True:

cursor.updateRow(row)

I hope this is helpful.

Re: Replace Null values with 0 in many fields

JAKERODEL — Wed, 02 Mar 2016 18:55:55 GMT

Perfect. Thanks to both of you!