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[Solved] ValueError: Grouper for not 1-dimensional

Hello Guys, How are you all? Hope You all Are Fine. Today I get the following error ValueError: Grouper for something not 1-dimensional in python. So Here I am Explain to you all the possible solutions here.

Without wasting your time, Let’s start This Article to Solve This Error.

How ValueError: Grouper for something not 1-dimensional Error Occurs?

Today I get the following error ValueError: Grouper for not 1-dimensional in python.

How To Solve ValueError: Grouper for something not 1-dimensional Error ?

  1. How To Solve ValueError: Grouper for something not 1-dimensional Error ?

    To Solve ValueError: Grouper for not 1-dimensional Error Figure out which one you want to use, rename or drop the other column and redo the operation.

  2. ValueError: Grouper for something not 1-dimensional

    To Solve ValueError: Grouper for not 1-dimensional Error Figure out which one you want to use, rename or drop the other column and redo the operation.

Solution 1


Simplified problem

I also ran into this problem and found that it was caused by duplicate column names.

To recreate this:

df = pd.DataFrame({"foo": [1,2,3], "bar": [1,2,3]})
df.rename(columns={'foo': 'bar'}, inplace=True)

   bar  bar
0    1    1
1    2    2
2    3    3

df.groupby('bar')

ValueError: Grouper for 'bar' not 1-dimensional

Just like a lot of cryptic pandas errors, this one too stems from having two columns with the same name.

Figure out which one you want to use, rename or drop the other column and redo the operation.

Solution

Rename the columns like this

df.columns = ['foo', 'bar']

   foo  bar
0    1    1
1    2    2
2    3    3

df.groupby('bar')
<pandas.core.groupby.DataFrameGroupBy object at 0x1066dd950>

Solution 2

Happened to me when I accidentally created MultiIndex columns:

>>> values = np.asarray([[1, 1], [2, 2], [3, 3]])

# notice accidental double brackets around column list
>>> df = pd.DataFrame(values, columns=[["foo", "bar"]])

# prints very innocently
>>> df
  foo bar
0   1   1
1   2   2
2   3   3

# but throws this error
>>> df.groupby("foo")
ValueError: Grouper for 'foo' not 1-dimensional

# cause:
>>> df.columns
MultiIndex(levels=[['bar', 'foo']],
           labels=[[1, 0]])

# fix by using correct columns list
>>> df = pd.DataFrame(values, columns=["foo", "bar"])
>>> df.groupby("foo")
<pandas.core.groupby.groupby.DataFrameGroupBy object at 0x7f9a280cbb70>

Summery

It’s all About this issue. Hope all solution helped you a lot. Comment below Your thoughts and your queries. Also, Comment below which solution worked for you? Thank You.

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