How to write a nested python dict to csv with row being key, value, key, value

Question

I have a nested dict that looks like:

{KeyA: {'ItemA': 1, 'ItemB': 2, 'ItemC': 3, 'ItemD': 4, 'ItemE': 5, 'ItemF': 6},
{KeyB: {'ItemR': 2, 'ItemQ': 3, 'ItemG': 4, 'ItemZ': 5, 'ItemX': 6, 'ItemY': 7}

I would like to output this to a csv where the desired row format is:

ItemA, 1, Item B, 2, ItemC, 3, ItemD, 4, ItemE, 5, ItemF, 6

I've managed to get a row that's keys and then another below it with the associated value with the below code:

for item in myDict:
    item = myDict[x]
    itemVals = item.values()
    wr.writerow(item)
    wr.writerow(itemVals)
    x += 1

I've tried a number of ways of reformatting this and keep running into subscriptable errors every which way I try.

The length of the top level dict could be large, up to 30k nested dicts. The nested dicts are a constant length of 6 key:value pairs, currently.

What's a clean way to achieve this?

Do you want KeyA[ItemA] to be one row above KeyB[ItemR] in the CSV, or do you only want to print the csv row for KeyA? Would be cool if you could make the desired output a bit more clear :) — Luchspeter
– Luchspeter, Commented Dec 4, 2021 at 7:23

Erik McKelvey · Accepted Answer · 2021-12-04 08:16:43Z

1

Here is an implementation with loops:

myDict = {'KeyA': {'ItemA': 1, 'ItemB': 2, 'ItemC': 3, 'ItemD': 4, 'ItemE': 5, 'ItemF': 6},
'KeyB': {'ItemR': 2, 'ItemQ': 3, 'ItemG': 4, 'ItemZ': 5, 'ItemX': 6, 'ItemY': 7}}

with open("output.csv", "w") as file:
    for key in myDict:
        for nestedKey in myDict[key]:
            file.write(key + "," + str(myDict[key][nestedKey]) + ",")
        file.write("\n")

output.csv:

KeyA,1,KeyA,2,KeyA,3,KeyA,4,KeyA,5,KeyA,6,
KeyB,2,KeyB,3,KeyB,4,KeyB,5,KeyB,6,KeyB,7,

answered Dec 4, 2021 at 8:16

Erik McKelvey

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