python pandas replacing strings in dataframe with numbers

Question

Is there anyway to use the mapping function or something better to replace values in an entire dataframe?

I only know how to perform the mapping on series.

I

Answer 1

You can use the applymap DataFrame function to do this:

In [26]: df = DataFrame({"A": [1,2,3,4,5], "B": ['a','b','c','d','e'],
                         "C": ['b','a','c','c','d'], "D": ['a','c',7,9,2]})
In [27]: df
Out[27]:
   A  B  C  D
0  1  a  b  a
1  2  b  a  c
2  3  c  c  7
3  4  d  c  9
4  5  e  d  2

In [28]: mymap = {'a':1, 'b':2, 'c':3, 'd':4, 'e':5}

In [29]: df.applymap(lambda s: mymap.get(s) if s in mymap else s)
Out[29]:
   A  B  C  D
0  1  1  2  1
1  2  2  1  3
2  3  3  3  7
3  4  4  3  9
4  5  5  4  2