calculating rolling average using python -

i've started learning python. using write script calculate salt inflow rolling average. have data that

date    a4260502_flow   a4261051_flow   a4260502_ec a4261051_ec 25/02/1970  1304    0   411 0   1304             26/02/1970  1331    0   391 0   1331             27/02/1970  0   0   420 411 0            28/02/1970  0   0   400 391 0            1/03/1970   0   0   0   420 0            2/03/1970   1351    1304    405 400 1327.5       3/03/1970   2819    1331    415 405 2075         4/03/1970   2816    0   413 0   2816             5/03/1970   0   1351    0   415 1351             6/03/1970   0   0   0   0   0            7/03/1970   0   2819    0   413 2819             8/03/1970   0   0   0   0   0            9/03/1970   0   2816    0   412 2816 

and script is

inputfilename = "output.csv" outputfilename = "si_calculation.csv"  # open files infile = open(inputfilename,"r+") outfile = open(outputfilename,'w')  # initialise variables   ec_conversion = 0.000525 rolling_avg = 5 flow_avg_list = [] si_list = [] si_ra_list = [] si_ra1 = []  # import module import csv import numpy                 #l20   table = [] reader = csv.reader(infile)         #read row in csv.reader(infile):     table.append(row) infile.close()  r in range(1,len(table)):             c in range(1,len(row)): #l30         table[r][c] = float(table[r][c])   #calculating flow average r in range(1,len(table)):      flow1 = table[r][1]     flow2 = table[r][2]     if flow1 == 0.0:                          flow_avg = flow2            #l40     elif flow2 == 0.0:         flow_avg = flow1     else:         flow_avg = (flow1+flow2)/2     flow_avg_list.append(flow_avg)  #calculating salt inflow r in range(1,len(table)):     s1 = table[r][3]                                    s2 = table[r][4]        #l50     if s1 == 0.0 or s2 == 0.0 or flow_avg_list[r-1] == 0.0:         si = 0.0     else:         si = ec_conversion*flow_avg_list[r-1]*(s2-s1)     si_list.append(si) print si_list      #calculating rolling average salt inflow r in range(1,len(table)):                      if r < 5:       #rolling-avg = 5         in range(0,r+5):      #l60             s = si_list[i]             si_ra1.append(s)         si_ra = numpy.mean(si_ra1)         si_ra_list.append(si_ra)     elif r > (len(table) - 4):         in range(r-5,len(table)-1):             s = si_list[i]             si_ra1.append(s)         si_ra = numpy.mean(si_ra1)         si_ra_list.append(si_ra)    #l70     else:         in range(r-5,r+5):             s = si_list[i]       #line 73             si_ra1.append(s)         si_ra = numpy.mean(si_ra1)         si_ra_list.append(si_ra) print si_ra_list 

when ran script gave me error: line 73: list index out of range. know error be? sorry long script. don't know how shorten yet.

on line 65, change condition to:

elif r > (len(table) - 5): 

the problem iterate towards end of list on line 73, trying next 5 datapoints in list, there 4 datapoints left in list, indexing beyond length of list, hence exception thrown.