Pythonic way to create a dict of Excel column values

Question

I have an Excel worksheet and I want to create a dict which has the cell values as a list with cell column being the key. Let say that spreadsheet has data that looks like,

A B C (columns)
1 2 
3 4
5 f

I want a dict that looks like,

cbyc = {'A': [1,3,5]; 'B':[2,4,f]; 'C';[None, None, None]}

I am doing this with the following code

import openpyxl as oxl
wb = oxl.load_workbook('myxlworkbook.xlsx')
sheet = wb.get_sheet_by_name('Sheet1')
allcells = sheet.get_cell_collection()

cbyc = {}
for c in allcells:
    if c.value is not None:
        if c.column not in cbyc.keys():
            cbyc[c.column] = [c.value]
        else:
            cbyc[c.column].append(c.value)

And this work,.. but I am sure there is a more efficient way to create this dict with the if.. else logic

is there a better way? Maybe there is something in the openpyxl that can give such a list

Answer 1

Whenever I see an unsightly loop filling a dict or a list , I try to replace it with a dict comprehension or a list comprehension. In this case, I'd use both.

This program might do what you want:

import openpyxl as oxl
wb = oxl.load_workbook('myxlworkbook.xlsx')
sheet = wb.get_sheet_by_name('Sheet1')

cybc = {
    col[0].value: [cell.value for cell in col[1:]]
    for col in sheet.columns
}

print(cybc)

However, we can avoid all of the .value code if we invoke sheet.values to start with:

cybc = { col[0]: col[1:] for col in zip(*sheet.values) }

Answer 2

You can replace:

if c.column not in cbyc.keys():
    cbyc[c.column] = [c.value]
else:
    cbyc[c.column].append(c.value)

with:

cby.setdefault(c.column, []).append(c.value)

 setdefault(key[, default]) 

If key is in the dictionary, return its value. If not, insert key with a value of default and return default. default defaults to None.

See docs .

Answer 3

from collections import defaultdict

cbyc = defaultdict(list)

for cell in all_cells:
    if cell.value is None:
        continue
    cbyc[cell.column].append(cell.value)

See documentation on defaultdict .