Alter Field & Add Portion of Filename to Field Name

Question

I have 350 tables in a geodatabase. Using a python script I want to iterate through all 350 tables and alter the field names of 3 fields in each table.

I'd like the new field names to contain part of the table's file name. For example, for a table named, chirps_1982_02_stat, I could separate out parts of the file name so that the new field names only had the year and month (1982_02) added to them. The desired field names would change from:

• SUM_grid_code -> Sum_precip_1982_02,
• MEAN_grid_code -> mean_precip_1982_02
• STD_grid_code -> std_precip_1982_02.

I'm very new to python so I've found instructions on altering a field name but I'm not sure how to parse out the elements of the file's name and add it to the new field name. I am also not sure how to format the code so that I can do this process 3 times, 1 time for each field name I want to change

What I've found for altering field name

>>> arcpy.env.workspace = r'D:\myfolder\mygdb.gdb'
>>> fcList = arcpy.ListFeatureClasses() #get a list of feature classes
... for fc in fcList:  #loop through feature classes
...   fieldList = arcpy.ListFields(fc)  #get a list of fields for each feature class
     for field in fieldList: #loop through each field
...         if field.name.lower() == 'MEAN_grid_code':  #look for the name MEAN_grid_code
...            **arcpy.AlterField_management(fc, field.name, 'Mean Precip %fileyear%', 'Mean Precip XXXX_XX')**

Answer 1

First, there is an issue with your AlterField_management(). the third parameter in the method is the new field name which cannot contain spaces or special characters. It would need to be in the format of "Mean_Precip_1982_02".

Second, your if statement "if field.name.lower() == "MEAN_grid_code"". you are never going to have a match on that statement since the string you are comparing it to has capital letters in it.

you would essentially be doing something like the following:

'mean_grid_code' == 'MEAN_grid_code'

which is false.

instead try

field.name.lower() == "mean_grid_code":

or

field.name == "MEAN_grid_code":

so rewritten:

import arcpy

arcpy.env.workspace = r'D:\myfolder\mygdb.gdb'

for fc in arcpy.ListFeatureClasses():
    for field in arcpy.ListFields(fc):
        file_year = fc.split('_')[-2]
        field_alias = '_'.join(fc.split('_')[-2:])
        if field.name.lower() == "mean_grid_code":
            arcpy.AlterField_management(fc, field.name, 'Mean_Precip_{0}'.format(file_year), 'Mean Precip {0}'.format(field_alias))
        elif field.name.lower() == "sum_grid_code":
            arcpy.AlterField_management(fc, field.name, 'Sum_precip_{0}'.format(file_year), 'Sum precip {0}'.format(field_alias))
        elif field.name.lower() == "std_grid_code":
            arcpy.AlterField_management(fc, field.name, 'std_precip_{0}'.format(file_year), 'std precip {0}'.format(field_alias))
        else:
            pass