Renaming files in a numerical sequence + letters

Question

I have a folder containing .png images that are named image1.png, image2.png, image3.png etc.

The way this folder is organized, 3 consecutive images represent data from the same subject, so I'd like them to be named with the same identifying number + a letter to differentiate them. Like this:

image1.png --> 1-a.png
image2.png --> 1-b.png
image3.png --> 1-c.png
image4.png --> 2-a.png
image5.png --> 2-b.png
image6.png --> 2-c.png

and so on.

What would be the best way to do this? a Perl script? or generating a .txt in python with the desired names and then using it to rename the files? I'm using Ubuntu.

Thanks in advance!

Almost any scripting language would be sufficient. Why not give it a try and see how you get along? — Sobrique, Mar 06 '19 at 13:29
the script should handle sorting logic as well or you can make it sort in certain order? Because we don't know what is exactly the filename pattern. You mentioned `image01` and `image1` in your question — Kent, Mar 06 '19 at 13:53
@Kent The files are already sorted, and there are no leading zeros. Thanks for pointing that out - I just edited the question. — gantry, Mar 06 '19 at 14:01

blhsing · Accepted Answer · 2019-03-06T13:44:05.173

1

Given a file list files in Python, you can use itertools.product to generate your desired pairings of numbers and letters:

from itertools import product
import os

os.chdir(directory_containing_images)
# instead of hard-coding files you will actually want:
# files = os.listdir('.')
files = ['image1.png', 'image2.png', 'image3.png', 'image4.png', 'image5.png', 'image6.png']
for file, (n, a) in zip(files, product(range(1, len(files) // 3 + 2), 'abc')):
    os.rename(file, '{}-{}.png'.format(n, a))

If you replace os.rename with print, the above code will output:

image1.png 1-a.png
image2.png 1-b.png
image3.png 1-c.png
image4.png 2-a.png
image5.png 2-b.png
image6.png 2-c.png

edited Mar 06 '19 at 13:44

answered Mar 06 '19 at 13:35

blhsing

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I ended up going with this solution. I had to add human/natural sorting to fix order issues such as `image1.png` being followed by `image10.png`. This question was helpful for that: https://stackoverflow.com/questions/5967500/how-to-correctly-sort-a-string-with-a-number-inside – gantry Mar 06 '19 at 15:36

score 0 · Answer 2 · answered Mar 06 '19 at 13:54

0

In perl you could do:

my @new_names = map {
    my ( $n ) = $_ =~ /image(\d+)\.png/;
    my $j = (($n - 1)  % 3) + 1;
    my $char = (qw(a b c))[ int( $n / 3 ) ];
    "$j-$char.png"
} @files;

This assumes no special ordering of the @files array.

answered Mar 06 '19 at 13:54

Håkon Hægland

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score 0 · Answer 3 · answered Mar 06 '19 at 15:09

Fun project. :)

declare -i ctr=1 fileset=1              # tracking numbers
declare -a tag=( c a b )                # lookup table
for f in $( printf "%s\n" *.png |       # stack as lines
            sort -k1.6n )               # order appropriately
do ref=$(( ctr++ % 3 ))                 # index the lookup
   end=${f##*.}                         # keep the file ending
   mv "$f" "$fileset-${tag[ref]}.$end"  # mv old file to new name
   (( ref )) || (( fileset++ ))         # increment the *set*
done

mv image1.png 1-a.png
mv image2.png 1-b.png
mv image3.png 1-c.png
mv image4.png 2-a.png
mv image5.png 2-b.png
mv image6.png 2-c.png
mv image7.png 3-a.png
mv image8.png 3-b.png
mv image9.png 3-c.png
mv image10.png 4-a.png
mv image11.png 4-b.png
mv image12.png 4-c.png

Obviously, edit as needed for pathing &c.

score 0 · Answer 4 · answered Mar 07 '19 at 06:32

I tried this in python3 and its working as per your need.

import os
import string
os.chdir(path_to_your_folder)
no=1
count=1
alphabet = ['a','b','c']
count=0
for filename in os.listdir(os.getcwd()):
    newfilename = (str(no) + "-" + alphabet[count]+".png")
    os.rename(filename,newfilename)
    count=(count+1)%3
    if count==0:
        no=no+1

Renaming files in a numerical sequence + letters

4 Answers4