class_docstr: Preallocation strategies for rolling window over expanding data set
  
  Restrictions: major_axis can only be a DatetimeIndex for now
class_docstr_tok: ["Preallocation","strategies","for","rolling","window","over","expanding","data","set","Restrictions",":","major_axis","can","only","be","a","DatetimeIndex","for","now"]
code: def set_items(self, items):
      self.items = _ensure_index(items)
      self.buffer = self.buffer.reindex(items=self.items)
  
imports: import datetime
  from copy import deepcopy
  import numpy
  import pandas
label_desc: Use image node_id 7 for calling the RollingPanel obj's underlying member method code with example usage: obj.set_items(items) without return types