ValueError: Grouper for 'target' not 1-dimensional

This error occurs when the 'target' variable used for grouping is not one-dimensional. In other words, it contains more than one column or feature.

To resolve this error, you need to make sure that the 'target' variable used for grouping is one-dimensional. You can do this by selecting only the necessary column or feature from the dataset.

For example, if you have a dataset with columns 'x', 'y', and 'target', and you want to group by the 'target' column, you should select only the 'target' column before grouping:

df = df[['target']] # select only the 'target' column
grouped_df = df.groupby(['target']).mean() # group by the 'target' column

This will ensure that the 'target' variable used for grouping is one-dimensional and the error will be resolved.