python - Implement rms without numpy -

i have implement function calculate rms without using numpy, using data in txt. have following:

import numpy np import matplotlib.pyplot plt import math  def main():      # cargando los datos      avrgpress = []     press = []      open("c:\users\saulo\downloads\prvspy.txt","r") a:         x in a:             columnas = x.split('\t')             avrgpress.append(float(columnas[0]))             press.append(float(columnas[1]))  def error(avrgpress, press):     lista3 = [0]*len(lista)     x in xrange(len(lista)):         lista3[x] = lista3[x] * sum(sqrt(float(1.0/1064) * (avrgpress - press)**2))      return lista3  if __name__ == '__main__':     main() 

when building, not out rms. suggestions or solution?

is want, rms( avrgpress ) ?

from __future__ import division  # necessary import math  def rms( alist ):     """ rms( [1, 2, 3] ) = sqrt( average( 1**2 + 2**2 + 3**2 )) = 2.16 """     sum_squares = sum([ x**2 x in alist ])     return math.sqrt( sum_squares / len(alist) )  ... print rms( [1, 2, 3] )