Removing characters from a Feature Class file name

[MichaelTomiak]

This should be a simple answer ... I'm trying to just remove the first 25 characters from a list (>90 in number) of Feature classes (raster datasets) within a .gdb.

All the file names are named the same except for the last 9 digits (hence why I am trying to remove the first 25).
I would then like to add some standard text to all the FCs (in the example "Hello")

My attempt from other threads comprises the following (but has not worked so far):

-------------------

import arcpy
import os

dir = r'C:\Users\X\Desktop\X\X.gdb'

arcpy.env.workspace = dir

for ras in arcpy.ListRasters ("*"):
print (ras)    #original raster name
basename = ras.split("*")[:25]    #strips the first 25 characters from original raster name
newrastername = "Hello" + basename
print (newrastername)
arcpy.CopyRaster_management(ras, newrastername)   #create a new raster with the new/updated name

----------------------

Error received:

---------------------------------------------------------------------------
SyntaxError                               Traceback (most recent call last)
File C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\Lib\ast.py, in parse:
Line 35:    return compile(source, filename, mode, PyCF_ONLY_AST)

SyntaxError: Missing parentheses in call to 'print'. Did you mean print(ras #original raster name)? (<string>, line 😎

[DavidPike]

Can you share your print statement returns and your error messages?  It looks ok, but what is ras.split("*") for?

[MichaelTomiak]

yes apologies

It is to try to remove the first 25 (took the split from some research on line, but likely not the most sensible function to use)

[DavidPike]

well that's not quite right.  Just use 

basename = ras[:25]

and forget about the .split("*") unless you want to create a list of strings split at an asterisk *.  in that case use

basename = ras.split("*")[0][:25]

Edit - I also think you need [25:] not [:25]

[DanPatterson]

split produces pieces, you have to determine which one first then slice off the characters.  For example

ras = "left*right"

ras.split("*")[0][:2]
'le'

ras.split("*")[1][:2]
'ri'

ras.split("*")[0][-2:]
'ft'

ras.split("*")[1][-2:]
'ht'

or skip the split

ras[-5:]
'right'

ras[:5]
'left*'

[MichaelTomiak]

thank you. However I'm still getting an 'indentation' error:

IndentationError                          Traceback (most recent call last)
File C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\Lib\ast.py, in parse:
Line 35:    return compile(source, filename, mode, PyCF_ONLY_AST)

IndentationError: expected an indented block (<string>, line 10)

Original code:

import arcpy
import os

dir = r'C:\Users\Michael.Tomiak\Desktop\25\Copy.gdb'

arcpy.env.workspace = dir

for ras in arcpy.ListRasters ("*"):
print (ras)
basename = ras[25:] #strips the first 25 characters from original raster name
newrastername = basename
print (newrastername)
arcpy.CopyRaster_management(ras, newrastername) #create a new raster with the new/updated name

[DavidPike · Accepted solution]

import arcpy
import os

dir = r'C:\Users\X\Desktop\X\X.gdb'


arcpy.env.workspace = dir

for ras in arcpy.ListRasters ("*"):
    #print (ras)    #original raster name
    #print(ras.split("*"))
    basename = ras[25:]    #strips the first 25 characters from original raster name
    newrastername = "Hello" + basename
    print (newrastername)
    arcpy.CopyRaster_management(ras, newrastername)   #create a new raster with the new/updated name

[MichaelTomiak]

Thanks. Worked well. Didn't know indentation was required for it to run. Thought it was a presentation aspect. 

WRT to the last line of code, what function could replace this so that it was only renaming the original files, rather than making a copy of the data (which is useful sometimes) but I do not have much data storage capacity left. Making a copy might be tight.

 
Would it be something like:
arcpy.RenameRaster_management (ras, newrastername)

[DavidPike]

import arcpy
#import os #youre not using os so dont import it

dir = r'C:\Users\X\Desktop\X\X.gdb'


arcpy.env.workspace = dir

for ras in arcpy.ListRasters ("*"):
    #print (ras)    #original raster name
    #print(ras.split("*"))
    basename = ras[25:]    #strips the first 25 characters from original raster name
    newrastername = "Hello" + basename
    print (newrastername)
    arcpy.Rename_management(ras, newrastername)   #rename raster with the new/updated name

[MichaelTomiak]

Worked a treat 😀- thanks for your time and effort David.  Saved me an awful lot of manual renaming tonight.