class_docstr: Imputes missing values by using the most recent value.
  
  Examples
  --------
  
  >>> from river import preprocessing
  
  >>> imputer = preprocessing.PreviousImputer()
  
  >>> imputer.learn_one({'x': 1, 'y': 2})
  >>> imputer.transform_one({'y': None})
  {'y': 2}
  
  >>> imputer.transform_one({'x': None})
  {'x': 1}
class_docstr_tok: ["Imputes","missing","values","by","using","the","most","recent","value",".","Examples","--","--","--","--",">",">",">","from","river","import","preprocessing",">",">",">","imputer","=","preprocessing.PreviousImputer","(",")",">",">",">","imputer.learn_one","(","{","'","x","'",":","1",",","'","y","'",":","2","}",")",">",">",">","imputer.transform_one","(","{","'","y","'",":","None","}",")","{","'","y","'",":","2","}",">",">",">","imputer.transform_one","(","{","'","x","'",":","None","}",")","{","'","x","'",":","1","}"]
code: def __init__(self):
      self._latest = {}
  
file_path: river/river/preprocessing/impute.py
imports: from __future__ import annotations
  import typing
  from river import base, stats
label_desc: Use image node_id 1 to create a new PreviousImputer object from inherited base classes: base with example: obj = PreviousImputer()