pythonpython-3.xpandasdivide

Is it possible to divide one dataframe with another dataframe?


Here is the head of my first dataframe, A1:

            K37L  K37M  K37N  K37P  K37Q  K37R  K37S  K37T  K37U  K37V  ...   \
1997-01-01  79.8  80.4  72.8  36.7   0.0  90.0  96.9  92.2  79.8  93.7  ...    
1997-02-01  79.1  81.7  73.6  36.7   0.0  90.2  97.4  92.2  80.3  93.5  ...    
1997-03-01  79.2  80.8  73.2  37.0   0.0  90.3  97.5  92.0  80.4  93.2  ...    

            K385  K386   K387  K388  K389  K38A  K38B  K38C  K38D  K38E  
1997-01-01  67.4  79.1  227.0  83.8  82.1  94.0  74.2  88.4  81.1  73.9  
1997-02-01  67.5  79.2  220.9  83.9  82.1  94.2  74.5  88.5  81.1  74.3  
1997-03-01  67.5  79.3  218.9  84.0  82.2  94.3  74.7  88.7  81.1  74.4  

[3 rows x 27 columns]

Here is the head of my second dataframe, A2:

            K37L  K37M  K37N  K37P  K37Q  K37R  K37S  K37T  K37U  K37V  ...   \
1996-01-01  78.9  79.4  71.7  36.7   0.0  88.7  94.1  90.7  80.2  98.9  ...    
1996-02-01  79.3  81.0  72.7  36.7   0.0  88.7  94.3  90.9  79.8  98.7  ...    
1996-03-01  79.8  80.4  72.7  36.7   0.0  89.0  94.6  91.0  79.6  98.6  ...    

            K385  K386   K387  K388  K389  K38A  K38B  K38C  K38D  K38E  
1996-01-01  70.9  78.7  257.8  83.9  79.7  92.2  73.8  86.4  79.6  74.0  
1996-02-01  70.7  78.7  257.2  83.9  79.8  92.6  73.7  86.6  79.9  73.9  
1996-03-01  70.9  78.7  257.3  83.9  80.1  92.6  73.8  87.2  80.1  74.0  

[3 rows x 27 columns]

What I want to do is: A2 / (A1 - 1) * 100

The most important part is that I want to divide all the values in A1 with A2.

My attempt:

A3 = A2 / (A1-1)*100
print(A3.head(3))

Yields:

            K37L  K37M  K37N  K37P  K37Q  K37R  K37S  K37T  K37U  K37V  ...   \
1996-01-01   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN  ...    
1996-02-01   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN  ...    
1996-03-01   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN  ...    

            K385  K386  K387  K388  K389  K38A  K38B  K38C  K38D  K38E  
1996-01-01   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN  
1996-02-01   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN  
1996-03-01   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN   NaN  

[3 rows x 27 columns]

Is it possible to divide an entire dataframe (its values) from another dataframe? Or am I going to have to construct some sort of complex loop to achieve this?


Solution

  • This is because pandas will match by index (here by date) in order to apply the division. The dates don't match so no operation will take place.

    You can try this:

    A3 = A2.reset_index(drop=True) / (A1.reset_index(drop=True) - 1) * 100
    

    You can then reapply whichever index you wish:

    A3.index = A1.index  # for instance