Pandas Reshape dataframe without using melt function-CodePudding

I have a dataframe as :

i need to convert it as final result like this

I need the rows name and id with value 1 as according on last 3 columns as shown in the image. It can be done using pandas melt function but i was looking forward to do without using the library.

How can it be done??

CodePudding user response：

melt is designed for these operations, but an alternative would be to set your index on id and name, using set_index(), and use stack:

df.set_index(['id','name']).stack()\
                           .reset_index(name='val')\
                           .query('val == 1')\
                           .rename({'level_2':'language'},axis=1)\
                           .drop('val',axis=1)

prints:

   id    name language
0   1    Alex   python
1   1    Alex     java
2   1    Alex    mysql
3   2  Herald   python
5   2  Herald    mysql
6   3    Jack   python
9   4    Mike   python