class_docstr: Apply a transformer columnwise to multivariate series.
  
  Overview: input multivariate time series and the transformer passed
  in `transformer` parameter is applied to specified `columns`, each
  column is handled as a univariate series. The resulting transformed
  data has the same shape as input data.
  
  Parameters
  ----------
  transformer : Estimator
      scikit-learn-like or sktime-like transformer to fit and apply to series.
  columns : list of str or None
          Names of columns that are supposed to be transformed.
          If None, all columns are transformed.
  
  Attributes
  ----------
  transformers_ : dict of {str : transformer}
      Maps columns to transformers.
  columns_ : list of str
      Names of columns that are supposed to be transformed.
  
  See Also
  --------
  OptionalPassthrough
  
  Examples
  --------
  >>> from sktime.datasets import load_longley
  >>> from sktime.transformations.series.detrend import Detrender
  >>> from sktime.transformations.compose import ColumnwiseTransformer
  >>> _, X = load_longley()
  >>> transformer = ColumnwiseTransformer(Detrender())
  >>> Xt = transformer.fit_transform(X)
code: def __init__(self, transformer, columns=None):
      self.transformer = transformer
      self.columns = columns
      super().__init__()
  
      tags_to_clone = [
          "y_inner_mtype",
          "capability:inverse_transform",
          "handles-missing-data",
          "X-y-must-have-same-index",
          "transform-returns-same-time-index",
          "skip-inverse-transform",
      ]
      self.clone_tags(transformer, tag_names=tags_to_clone)
  
imports: import pandas
  from sktime.base._meta import _ColumnEstimator, _HeterogenousMetaEstimator
  from sktime.transformations.base import BaseTransformer
  from sktime.utils.multiindex import rename_multiindex
  from sktime.utils.validation.series import check_series
label_desc: Use image node_id 1 to create a new ColumnwiseTransformer object from inherited base classes: BaseTransformer with example: obj = ColumnwiseTransformer(transformer, columns)