Concatenating Python Data

Question

I have two distinct Python DataFrames (i.e., with a size of 2*2) as follows:

Mangoes    Apples
Mangoes    Apples

and,

1         0
0         1

I intend to generate a third DataFrame, so that the output could be:

Mangoes       0
0        Apples

Obviously, i can't multiply both of these Data Frames (i wish i could have done). So, what should be the best way of doing this? Is this something that can be done by Concatenation? or should i start iterating item-by-item for each DataFrame and store the values into a third DataFrame.

MaxU - stand with Ukraine · Accepted Answer · 2017-07-16 12:54:25Z

1

Assuming that both DFs have the same column names and indexes:

In [123]: d1[d2.eq(1)].combine_first(d2)
Out[123]:
         0       1
0  Mangoes       0
1        0  Apples

Source DFs:

d1:

In [124]: d1
Out[124]:
         0       1
0  Mangoes  Apples
1  Mangoes  Apples

d2:

In [125]: d2
Out[125]:
   0  1
0  1  0
1  0  1

answered Jul 16, 2017 at 12:54

MaxU - stand with Ukraine

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Comments

niraj · Accepted Answer · 2017-07-16 14:16:04Z

0

One possible way may be as following:

print(df1)

Output:

         0       1
0  Mangoes  Apples
1  Mangoes  Apples

Other dataframe:

print(df2)

Output:

   0  1
0  1  0
1  0  1

Then:

df_new = (df1*df2).replace('',0)
print(df_new)

Output:

         0       1
0  Mangoes       0
1        0  Apples

answered Jul 16, 2017 at 14:16

niraj

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4 Comments

John Over a year ago

Thank you for the guidance. I have tried using this way, and am getting an error, "TypeError: can't multiply sequence by non-int of type 'str'".

niraj Over a year ago

@John The possible reason is data type of df2 is not integer or float instead it is string. So, the error is about trying to multiply two string. Can you verify data type for df2 in above example? You can try converting entire df2 to numeric by df2 = df2.apply(pd.to_numeric) and see if df_new = (df1*df2).replace('',0) works. To make simple test, you can try running 'mangoes' * 1 and compare to 'mangoes' * '1'. The later will possibly give same error as you mentioned.

John Over a year ago

Yes, it was the problem with data type of d2 ... its resolved. By the way, could you kindly elaborate a bit on this line ... df_new = (df1*df2).replace(' ',0) ... what exactly this (' ', 0) was doing

niraj Over a year ago

@John if you remove .replace('',0) from the line of code, then you will see empty cells i.e. to make simple test you can try: 'mangoes' * 0 will give ''. So, replacing those empty cells with 0. If it resolved your problem, you can accept the answer if you would like. Happy Coding.

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