Split pfd based off value and Merge dictionaries inside list in python

Question

I want to split a pdf based off a value on every page. Every value should be in its own pdf file. I currently have the following list where all values with the pages are displayed:

l = [
    {'abr': '123 ', 'page': 1},
    {'abr': '125 ', 'page': 2},
    {'abr': '125 ', 'page': 3},
    {'abr': '140 ', 'page': 4},
    {'abr': '142 ', 'page': 5},
]

I want to "merge" the dicts so that every "abr" is uniqe inside the list and i have every page of that specific abr added to a list.

I thought of something like the following:

l = [
    {'abr': '123 ', 'page': [1]},
    {'abr': '125 ', 'page': [2, 3]},
    {'abr': '140 ', 'page': [4]},
    {'abr': '142 ', 'page': [5]},
]

Thats because i need to have a for loop for every abr where i can get every page so can do something like:

pdf = PdfFileReader(path)
for abr in l:
    pdf_writer = PdfFileWriter()
    for page in abr["page"]:
        pdf_writer.addPage(pdf.getPage(page))
    
    with open(output_filename, 'wb') as out:
        pdf_writer.write(out)

Is there a good / simple way to do this or has anyone a better way to structure the data or can we split it easier?

score 1 · Accepted Answer · answered Aug 30 '22 at 09:39

If you're open to a new structure, given that you use the abr as a key, then you can put that as a key for a dict (or defaultdict in this case).

from collections import defaultdict

l = [
    {'abr': '123 ', 'page': 1},
    {'abr': '125 ', 'page': 2},
    {'abr': '125 ', 'page': 3},
    {'abr': '140 ', 'page': 4},
    {'abr': '142 ', 'page': 5},
]

abrs = defaultdict(list)

for d in l:
    abrs[d["abr"]].append(d["page"])

print(abrs)  # contains {'123 ': [1], '125 ': [2, 3], '140 ': [4], '142 ': [5]}

pdf = PdfFileReader(path)
for abr, pages in abrs.items():  # get key and value from dict
    pdf_writer = PdfFileWriter()
    for page in pages:  # iterate through pages
        pdf_writer.addPage(pdf.getPage(page))
    
    with open(output_filename, 'wb') as out:
        pdf_writer.write(out)

PS. you might not need both abr and pages from abrs.items(), you can iterate through abrs.values() instead to get pages only.

Split pfd based off value and Merge dictionaries inside list in python

1 Answers1