Get first and second highest values in pandas columns

Question

I am using pandas to analyse some election results. I have a DF, Results, which has a row for each constituency and columns representing the votes for the various parties (o

Answer 1

Here is a solution using nlargest function:

>>> df
    a   b   c
 0  4  20   2
 1  5  10   2
 2  3  40   5
 3  1  50  10
 4  2  30  15
>>> def give_largest(col,n):
...     largest = col.nlargest(n).reset_index(drop = True)
...     data = [x for x in largest]
...     index = [f'{i}_largest' for i in range(1,len(largest)+1)]
...     return pd.Series(data,index=index)
...
...
>>> def n_largest(df, axis, n):
...     '''
...     Function to return the n-largest value of each
...     column/row of the input DataFrame.
...     '''
...     return df.apply(give_largest, axis = axis, n = n)
...
>>> n_largest(df,axis = 1, n = 2)
   1_largest  2_largest
0         20          4
1         10          5
2         40          5
3         50         10
4         30         15
>>> n_largest(df,axis = 0, n = 2)
                  a           b           c     
1_largest         5          50           15
2_largest         4          40           10