rename index using index and name column

Question

I have the dataframe df

import pandas as pd
b=np.array([0,1,2,2,0,1,2,2,3,4,4,4,5,6,0,1,0,0]).reshape(-1,1)
c=np.array(['a','a','a','a','b','b','b','b','b','b','b','b','b','b','c','c','d','e']).reshape(-1,1)
df = pd.DataFrame(np.hstack([b,c]),columns=['Start','File'])


df
Out[22]: 
   Start File
0      0    a
1      1    a
2      2    a
3      2    a
4      0    b
5      1    b
6      2    b
7      2    b
8      3    b
9      4    b
10     4    b
11     4    b
12     5    b
13     6    b
14     0    c
15     1    c
16     0    d
17     0    e

I would like to rename the index using index_File in order to have 0_a, 1_a, ...17_e as indeces

piRSquared · Accepted Answer · 2017-08-08 15:55:15Z

4

You use set_index with or without the inplace=True

df.set_index(df.File.radd(df.index.astype(str) + '_'))

     Start File
File           
0_a      0    a
1_a      1    a
2_a      2    a
3_a      2    a
4_b      0    b
5_b      1    b
6_b      2    b
7_b      2    b
8_b      3    b
9_b      4    b
10_b     4    b
11_b     4    b
12_b     5    b
13_b     6    b
14_c     0    c
15_c     1    c
16_d     0    d
17_e     0    e

At the expense of a few more code characters, we can quicken this up and take care of the unnecessary index name

df.set_index(df.File.values.__radd__(df.index.astype(str) + '_'))

     Start File
0_a      0    a
1_a      1    a
2_a      2    a
3_a      2    a
4_b      0    b
5_b      1    b
6_b      2    b
7_b      2    b
8_b      3    b
9_b      4    b
10_b     4    b
11_b     4    b
12_b     5    b
13_b     6    b
14_c     0    c
15_c     1    c
16_d     0    d
17_e     0    e

edited Aug 8, 2017 at 15:55

answered Aug 8, 2017 at 15:23

piRSquared

296k68 gold badges509 silver badges654 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

EdChum · Accepted Answer · 2017-08-08 15:13:51Z

3

You can directly assign to the index, first by converting the default index to str using astype and then concatenate the str as usual:

In[41]:
df.index = df.index.astype(str) + '_' + df['File']
df

Out[41]: 
     Start File
File           
0_a      0    a
1_a      1    a
2_a      2    a
3_a      2    a
4_b      0    b
5_b      1    b
6_b      2    b
7_b      2    b
8_b      3    b
9_b      4    b
10_b     4    b
11_b     4    b
12_b     5    b
13_b     6    b
14_c     0    c
15_c     1    c
16_d     0    d
17_e     0    e

edited Aug 8, 2017 at 15:13

answered Aug 8, 2017 at 15:07

EdChum

397k204 gold badges836 silver badges583 bronze badges

1 Comment

user1717828 Over a year ago

So I don't usually see answers evolve as they're first written, but I watched this. Looks like you first posted a minimally working solution, then you fixed it up a touch, then you added some description of what you did at the top?

Collectives™ on Stack Overflow

rename index using index and name column

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related