CODEWITHSUNDEEP
pythonpandasdataframe
Chr Aber
Chr Aber

Reputation: 53

Pandas Can i duplicate rows and add a column with the values of a list?

I have a dataframe like this:

    ID value  repeat  ratio
  0 0  IDx10     6       0.5   
  1 1  IDx11     7       1.5   
  2 2  IDx12     8       2.5

and i have a list like this: l = [1,2]

What i want to do is to duplicate every row the number of times of the length of the list and in every new row put each value of the list.

And getting a dataframe like this:

    ID value  repeat  ratio  value
  0  0  IDx10  6       0.5    1
  1  0  IDx10  6       0.5    2
  2  1  IDx11  7       1.5    1 
  3  1  IDx11  7       1.5    2  
  4  2  IDx12  8       2.5    1  
  5  2  IDx12  8       2.5    2

Upvotes: 4

Views: 2610

Answers (2)

mozway
mozway

Reputation: 260735

Let us do a cross merge:

out = df.merge(pd.Series(l, name='value2'), how='cross')

output:

   ID  value  repeat  ratio  value2
0   0  IDx12       6    0.5       1
1   0  IDx12       6    0.5       2
2   0  IDx12       6    0.5       3
3   1  IDx12       7    1.5       1
4   1  IDx12       7    1.5       2
5   1  IDx12       7    1.5       3
6   2  IDx12       8    2.5       1
7   2  IDx12       8    2.5       2
8   2  IDx12       8    2.5       3

Upvotes: 7

I'mahdi
I'mahdi

Reputation: 24049

You can use numpy.repeat , numpy.tile and pandas.assign.

l = [1,2,3]
df = pd.DataFrame(np.repeat(df.values, len(l), axis=0), 
             columns=df.columns).assign(new_val=np.tile(l,len(l)))
print(df)

  ID  value repeat ratio  new_val
0  0  IDx12      6   0.5        1
1  0  IDx12      6   0.5        2
2  0  IDx12      6   0.5        3
3  1  IDx12      7   1.5        1
4  1  IDx12      7   1.5        2
5  1  IDx12      7   1.5        3
6  2  IDx12      8   2.5        1
7  2  IDx12      8   2.5        2
8  2  IDx12      8   2.5        3

Upvotes: 1

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