import os

DATAFILE='xrddata.dat'
PLOTFILE='xrddata.png'
LOWER=35
UPPER=36.5

f=os.popen('gnuplot' ,'w')
print >>f, "set xrange [%f:%f]" % (LOWER,UPPER)
print >>f, "set xlabel 'Diffraction angle'; set ylabel 'Counts [a.u.]'"
print >>f, "plot '%s' using 1:2:(sqrt($2)) with errorbars title 'XRPD data' lw 3" % DATAFILE
print >>f, "set terminal png large transparent size 600,400; set out '%s'" % PLOTFILE
print >>f, "pause 2; replot"
f.flush()