<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def mean_by_panel(self, length):
 """ Compute the mean across fixed sized panels of each record. Splits each record into panels of size `length`, and then computes the mean across panels. Panel length must subdivide record exactly. Parameters length : int Fixed length with which to subdivide. """

        self._check_panel(length)
        func = lambda v: v.reshape(-1, length).mean(axis=0)
        newindex = arange(length)
        return self.map(func, index=newindex)