Suppose I have a DataFrame "DS_df" containing strings ands numbers. The three columns "LAultimateparentcountry", "borrowerultimateparentcountry" and "tot" form a relationship.
How can I create a dictionary out of those three columns (for the entire dataset, while order matters)? I would need to access the two countries as one variable, and tot as another. I've tried the code below so far, but this merely yields me a list with separate items. For some reason, I am also not able to get.join to work, as the df is quite big (+900k rows).
new_list =[]
for i, row in DS_df.iterrows():
new_list.append(row["LAultimateparentcountry"])
new_list.append(row["borrowerultimateparentcountry"])
new_list.append(row["tot"])
Preferred outcome would be a dictionary, where I could access "Germany_Switzerland": 56708 for example. Any help or advice is much appreciated.
Cheers
You can use a dict this way:
countries_map = {}
for index, row in DS_df.iterrows():
curr_rel = f'{row["LAultimateparentcountry"]}_{row["borrowerultimateparentcountry"]}'
countries_map[curr_rel] = row["tot"]
If you are not wishing to not run over existing keys values
(and use their first appearance):
countries_map = {}
for index, row in DS_df.iterrows():
curr_rel = f'{row["LAultimateparentcountry"]}_{row["borrowerultimateparentcountry"]}'
if curr_rel not in countries_map.keys():
countries_map[curr_rel] = row["tot"]
When performing operations on a dataframe it's always good to think for a solution column-wise and not row-wise.
If your dataframe is having 900k+ rows then it might be a good option to apply vectorized operations on dataframe.
Below are two solutions:
Using pd.Series + to_dict():
pd.Series(DS_df.tot.values, index=DS_df.LAultimateparentcountry.str.cat(DS_df.borrowerultimateparentcountry, sep="_")).to_dict()
Using zip() + dict():
dict(zip(DS_df.LAultimateparentcountry.str.cat(DS_df.borrowerultimateparentcountry, sep="_"), DS_df.tot))
Test Dataframe:
DS_df = DataFrame({
'LAultimateparentcountry':['India', 'Germany', 'India'],
'borrowerultimateparentcountry':['France', 'Ireland', 'France'],
'tot':[56708, 87902, 91211]
})
DS_df
LAultimateparentcountry borrowerultimateparentcountry tot
0 India France 56708
1 Germany Ireland 87902
2 India France 91211
Output of both solutions:
{'India_France': 91211, 'Germany_Ireland': 87902}
If the formed key has duplicates then the value will be updated.
short answer -
zip() + dict() # if the rows are approx. below 1000000
pd.Series + to_dict() # if the rows are approx. above 1000000
Long answer - Below are the tests:
Test with 30 rows and 3 columns
zip() + dict()
%timeit dict(zip(DS_df.LAultimateparentcountry.str.cat(DS_df.borrowerultimateparentcountry, sep="_"), DS_df.tot))
297 µs ± 21 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
pd.Series + to_dict():
%timeit pd.Series(DS_df.tot.values, index=DS_df.LAultimateparentcountry.str.cat(DS_df.borrowerultimateparentcountry, sep="_")).to_dict()
506 µs ± 35.6 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
Test with 6291456 rows and 3 columns
pd.Series + to_dict()
%timeit pd.Series(DS_df.tot.values, index=DS_df.LAultimateparentcountry.str.cat(DS_df.borrowerultimateparentcountry, sep="_")).to_dict()
3.92 s ± 77.6 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
zip + dict()
%timeit dict(zip(DS_df.LAultimateparentcountry.str.cat(DS_df.borrowerultimateparentcountry, sep="_"), DS_df.tot))
3.97 s ± 226 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
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