CODEWITHSUNDEEP
pythonpython-2.7pandas
user2242044
user2242044

Reputation: 9213

Multiplying a Pandas column by a multi-index value

I had a multi-index dataframe with three levels on index. I would like to multiply each Percent value by the total population.

I am trying something like this:

df = df.reset_index(level=2, drop=True)
df['TOTAL'] = df['POP.'] * output['PERCENT']

I get KeyError: 'POP.'

Starting DataFrame

                               PERCENT  
     DATE      POP.  SEX                
2015-01-01     100  MALE        0.51  
                    FEMALE      0.49  
2016-01-01     200  MALE        0.52  
                    FEMALE      0.48

Desired Output

                               PERCENT     TOTAL  
     DATE      POP.  SEX                
2015-01-01     100  MALE        0.51         51  
                    FEMALE      0.49         49
2016-01-01     200  MALE        0.52        104
                    FEMALE      0.48         96

Upvotes: 2

Views: 1627

Answers (3)

MaxU - stand with Ukraine
MaxU - stand with Ukraine

Reputation: 210852

you can use DataFrame.eval() method:

In [118]: df = df.eval("TOTAL = PERCENT * POP", inplace=False)

In [119]: df
Out[119]:
                         PERCENT  TOTAL
DATE       POP   SEX
2015-01-01 100.0 MALE       0.51   51.0
                 FEMALE     0.49   49.0
2016-01-01 200.0 MALE       0.52  104.0
                 FEMALE     0.48   96.0

Upvotes: 2

prafi
prafi

Reputation: 950

You can also use multiply method and set axis="index" as follows:

df['TOTAL'] = df['POP'].multiply(df['PERCENT'], axis="index")

Upvotes: 2

BENY
BENY

Reputation: 323286

You need get_level_values + values

df['TOTAL']=(df.index.get_level_values('POP')*df['PERCENT']).values
df
Out[874]: 
                       PERCENT  TOTAL
DATE       POP SEX                   
2015-01-01 100 MALE       0.51   51.0
               FEMALE     0.49   49.0
2016-01-01 120 Male       0.52   62.4
               FEMALE     0.48   57.6

Upvotes: 5

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