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rsc05
rsc05

Reputation: 3810

How to rank columns of a dataframe by index? pandas

Suppose you have the following Dataframe (It is much more complicated)

df4=pd.DataFrame(np.matrix([[1,5],[3,2],[4,3],[5,4],[2,1]]),index=['a','b','c','d','e'])

Which is already ranked, however, I would like to rank it by the row index to reach the desired dataframe as

df5=pd.DataFrame(np.matrix([['a','e'],['e','b'],['b','c'],['c','d'],['d','a']]))

Is there an easy way of doing so?

Thank you very much

Upvotes: 0

Views: 248

Answers (2)

rsc05
rsc05

Reputation: 3810

I would like to rank the matrix based on index. I believe that the posted solution is not right for my question

I had to write a formula to answer this question 

def Column_rank_based_list(f):
    r,c=f.shape
    B= array(range(r*c), dtype='a5').reshape(r,c)
    for j in range(c):
        for i in range(r):
            B[f.ix[i,j]-1,j]=f.index[i]
    return pd.DataFrame(B, columns=f.columns)

However, I am having difficulty because it is printing b before the entries.

For example for 

df4=pd.DataFrame(np.matrix([[1,5],[3,2],[4,3],[5,4],[2,1]]),index=['a','b','c','d','e'])

you would obtain

Column_rank_based_list(df4)

Upvotes: 0

root
root

Reputation: 33803

Pass df4 as an indexer to the index of df4:

pd.DataFrame(df4.index[df4-1])

Note that I subtracted 1 from df4 since Pandas indexing is zero based, but your DataFrame appears to be 1 based.

The resulting output:

   0  1
0  a  e
1  c  b
2  d  c
3  e  d
4  b  a

Upvotes: 4

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