Matching indices with a corresponding identifier in python

Asked Feb 28 '20 at 11:11

Active Feb 28 '20 at 11:24

Viewed 12 times

I have a situation where I want to match some indices in one dataframe to there corresponding ids in another dataframe. My df1 looks like this :

my df2 looks like this :

Now I want to match the index columns in both the data frames and get the value from df2. The output should look like this :

  id id_df2
0  1   1234
1  2   2222
2  3   3333
3  4   3344

The thing is to match the pandas index columns that represents the row index for both the data frames. Net net I want to perform the following:

Match pandas default index column from df1 to pandas default index column in df2 to get the id from df2

edited Feb 28 '20 at 11:24

asked Feb 28 '20 at 11:11

Django0602

You could look at using something like `pd.concat` – Josmoor98 Feb 28 '20 at 11:14
If need something else, let me know. – jezrael Feb 28 '20 at 11:15
@Josmoor98: but I have some more columns as well in my df2, I do not want them in my final dataset. – Django0602 Feb 28 '20 at 11:15
@jezrael : That does not answer my question. My situation is different, I do want to append data, I need have my ids mapped with the indices. – Django0602 Feb 28 '20 at 11:17
@Django0602 - Why is `id=1` in final data? – jezrael Feb 28 '20 at 11:18
Possibly include a more complete example of your current data and what you expect the output to be – Josmoor98 Feb 28 '20 at 11:19
@jezrael: from my df1, for 0 index the value in id is 1 and then to match it with df2 with index 0 the id_df2 would be 1234 hence the final output for index 0 will be 1 and 1234 as shown in my post. – Django0602 Feb 28 '20 at 11:19
1

ok, why not match second, thitd, four row? – jezrael Feb 28 '20 at 11:20
@Josmoor98: added more description, if that helps. – Django0602 Feb 28 '20 at 11:21
@jezrael: we have to match all the rows. It will start from the 0 index and will run until 4999 which is my last row. – Django0602 Feb 28 '20 at 11:22
1

I'm not sure I understand your current output. From your description, shouldn't all the values from `id` and `id_df2` be in the output? – Josmoor98 Feb 28 '20 at 11:23
@Josmoor98: updated my output. all the rows should be there. – Django0602 Feb 28 '20 at 11:25
In that case, the suggested answer should solve your problem. Are the indices from both dataframes matching? i.e. `pd.concat([id, id_df2], axis=1)` – Josmoor98 Feb 28 '20 at 11:26
@Josmoor98: yes they match. but as I said if I have a situation where I have more columns in my data frame then pd.concat will fetch all other columns as well. I do not want that. – Django0602 Feb 28 '20 at 11:27
Are your column names `id` and `id_df2`? – Josmoor98 Feb 28 '20 at 11:28
2

I understand, need `pd.concat([df1['id'], df2['id_df2']], axis=1)` – jezrael Feb 28 '20 at 11:29

Matching indices with a corresponding identifier in python

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