class_docstr: Applies `to_sparse` as a FunctionTransformer 
class_docstr_tok: ["Applies","`","to_sparse","`","as","a","FunctionTransformer"]
code: def __init__(self):
      self.transformer_ = FunctionTransformer(to_sparse, validate=False)
  
imports: import warnings
  import pandas
  import numpy
  from scipy import sparse
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.preprocessing import MultiLabelBinarizer, FunctionTransformer, LabelEncoder, normalize
  from sklearn.feature_extraction.text import HashingVectorizer
  from sklearn import feature_selection
label_desc: Use image node_id 1 to create a new SparseTransformer object from inherited base classes: _CustomFunctionTransformer with example: obj = SparseTransformer()