class_docstr: Reader for Mat4 files 
class_docstr_tok: ["Reader","for","Mat4","files"]
docstr: Run when beginning read of variables
  
  Sets up readers from parameters in `self`
docstr_tok: ["Run","when","beginning","read","of","variables","Sets","up","readers","from","parameters","in","`","self","`"]
code: def initialize_read(self):
      """Run when beginning read of variables
  
      Sets up readers from parameters in `self`
      """
      self.dtypes = convert_dtypes(mdtypes_template, self.byte_order)
      self._matrix_reader = VarReader4(self)
  
imports: import sys
  import warnings
  import numpy
  import scipy.sparse
  from .miobase import MatFileReader, docfiller, matdims, read_dtype, convert_dtypes, arr_to_chars, arr_dtype_number
  from .mio_utils import squeeze_element, chars_to_strings
  from functools import reduce
label_desc: Use image node_id 3 for calling the MatFile4Reader obj's underlying member method code with example usage: obj.initialize_read() without return types