Python: How to sum up the values of a dictionary list in a column

Question

I have a DataFrame like this:

timestamp                                asks
2022-01-01 00:00:00                 [{'price':'0.99', 'size':'12311'},{'price':'0.991', 'size':'20013'}]
2022-01-01 01:00:00                 [{'price':'0.99', 'size':'3122'},{'price':'0.991', 'size':'43221'}]
...

What I want to do is sum up the values of size for eachtimestamp to get the following DataFrame:

timestamp                 asks
2022-01-01 00:00:00       32324
2022-01-01 01:00:00       46343
...

i.e. 12311+20013= 32324.

How can this be done (using pandas ideally)?

Asked By: MathMan 99

||

Source

Answer 1

df["asks"] = df["asks"].explode().str["size"].astype(int).groupby(level=0).sum()

get each dictionary on a separate row
get the "size" key’s value for each of them
- due to ducktyping, .str[...] works on anything that supports __getitem__ which a dictionary does
convert to integers and unexplode

to get

>>> df

             timestamp   asks
0  2022-01-01 00:00:00  32324
1  2022-01-01 01:00:00  46343

Answered By: Mustafa Aydın

Python: How to sum up the values of a dictionary list in a column

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