outfile = open('outfile.txt','w')
    DataIn = loadtxt('input.txt')
    s = DataIn.std()
    m = DataIn.mean()
    outfile.write(s + 'n')
    outfile.write(m + 'n')
    outfile.close()

import numpy
from numpy import *
DataIn = loadtxt('input.txt')
s = DataIn.std()
print s

outfile.write(str(s) + 'n')
outfile.write(str(m) + 'n')

outfile.write(str(s) + 'n')

outfile.write( "{0}n".format(s) )

print str(s)

def __add__(self, x):
    if isinstance(x, str):
        return str(self) + x
    ...

outfile.write(s + 'n')
outfile.write(m + 'n')

outfile.write('{:1.4f}n'.format(s))
outfile.write('{:1.4f}n'.format(m))