CODEWITHSUNDEEP
pythonpandasdataframe
user324
user324

Reputation: 351

Merging 2 dataframes

I am trying to merge the following 2 dataframes.

df.head():

        x     y     z   w
0  0.0056    11   824  51
1  0.0056   138   546  16
2  0.0056   328  1264  40
3  0.0056  1212   553  91
4  0.0056  1839   388  48

df1.head():

           x      y     z
0  5539.0567  12243    27
1  5873.2923  14474  1540
2  3975.9776  11353   699
3  1508.5975   8250   628
4    66.7913  11812   538

using the following command:

df1 = df1.merge(df, how='left',left_on=(['x','y','z']),right_index=True)

and the following error crops up:

ValueError: len(left_on) must equal the number of levels in the index of "right"

In total df has 11458060 rows and df1 has 2528243 rows

I don't really know what this means. Can anyone tell me what I might be doing wrong?

Upvotes: 1

Views: 3174

Answers (1)

jezrael
jezrael

Reputation: 862406

I think you need merge on columns x, y and z:

print df1.merge(df, how='left', on=['x','y','z'])

Docs.

Parameter on in merge:

on: Columns (names) to join on. Must be found in both the left and right DataFrame objects. If not passed and left_index and right_index are False, the intersection of the columns in the DataFrames will be inferred to be the join keys

Upvotes: 2

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