I'm using the following python code to replace Null values by 0, using field calculator:
def nulls(p1): if p1 is None: return 0 else: return p1
But nothing happens, Null values stay. I'm using ArcGIS Desktop 10.0.
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Since your code worked for me, a work around would be to use 'select by attribute' to select null rows e.g. MyField IS NULL. Once you have them all selected just use field calculator e.g. MyField = 0.
I recently had to replace Null values as well, but instead of the field calculator I used a short python script including an UpdateCursor, maybe this helps you:
with arcpy.da.UpdateCursor("feature_class, ["field_with_null_values"]) as cursor: for row in cursor: if row == None: row = 0 cursor.updateRow(row) print "Processing complete" del row
the only thing I don't know is if this works for 10.0, I work with 10.2
At 10.0, which does not have the Data Access module (arcpy.da), the code using old style cursors would look more like this:
cursor = arcpy.UpdateCursor(inFeatureClass) for row in cursor: if row.getValue(inField) == None: row.setValue(inField,0) cursor.updateRow(row) del row,cursor
The underlying cause of this problem seems to be bug number NIM059424 which was present in ArcGIS Desktop 10.0 and resolved by ArcGIS 10.1 for Desktop:
Null values in the feature class do not get replaced when using Python in the Field Calculator.
Your original code will work only if you are on edit session. Start editing the feature and run the code again. I´m having the same problem to calculate on Model builder.I´m using ArcGIS 10.4.