How to add a value inside an numpy array to a python dictionary

Question

i'm trying to loop through a pandas dataframe's columns (which consists of 1's and 0's) to groupby and sum another column then add the groupby column name to an empty dictionary as a key and the summed value as the value. But my current code adds an array as the value instead of the actual value. Here is some sample code below.

import pandas
sample_dict = {'flag1':[0,1,1,1,1,0],
               'flag2':[1,1,1,0,0,1],
               'flag3':[0,0,0,0,0,1],
               'flag4':[1,1,1,1,0,0],
               'flag5':[1,0,1,0,1,0],
               'dollars':[100,200,300,400,500,600]}
sample_df = pd.DataFrame(sample_dict)

ecols = sample_df.columns[:5]
rate = .46
empty_dict = {}
for i in ecols:
    df= sample_df[sample_df[i] == 1]
    yield1 = df.groupby(i)['dollars'].sum().values*rate
    empty_dict[i] = yield1
    
empty_dict

That code yields the following output:

Out[223]: 
{'flag1': array([644.]),
 'flag2': array([552.]),
 'flag3': array([276.]),
 'flag4': array([460.]),
 'flag5': array([414.])}

I would just like to have the actual integer as the value and not the array.

A true minimal reproducible example in a Pandas question! It deserves a +1... — Serge Ballesta
– Serge Ballesta, Commented Mar 11, 2021 at 13:55

Serge Ballesta · Accepted Answer · 2021-03-11 14:10:25Z

1

You consistently get an array of one single element: just take its first element (if it has one):

...
empty_dict[i] = yield1[0] if len(yield) >=1 else np.nan
...

edited Mar 11, 2021 at 14:10

answered Mar 11, 2021 at 13:54

Serge Ballesta

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4 Comments

Jordan Over a year ago

Thank you but I'm getting this:

Traceback (most recent call last):    File "<ipython-input-232-949311df9ecd>", line 9, in <module>     edit_dict[i] = prem[0]  IndexError: index 0 is out of bounds for axis 0 with size 0

Serge Ballesta Over a year ago

@Jordan Could your original code give empty arrays?

Jordan Over a year ago

Yes it can have a empty value.

Jordan Over a year ago

Thanks @SergeBallesta

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