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chuckv |
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#!/usr/bin/env python |
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"""Heat Flux Correlation function |
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Computes the correlation function of the heat flux vector |
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that has been stored in a stat file. These can be used to compute |
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the thermal conductivity. |
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Usage: stat2thcond |
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Options: |
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-h, --help show this help |
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-f, --stat-file=... use specified stat file |
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-o, --output-file=... use specified output (.pcorr) file |
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-e, --einstein use Einstein relation (based on Hess 2002 paper) |
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The Einstein relation option will compute: V*<(\int_0^t (S(t')-<S>)dt')^2>/2kT^2, |
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which will grow approximately linearly in time. The long-time slope of this |
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function will be the viscosity. |
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Example: |
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stat2thcond -f ring5.stat -o ring5.pcorr |
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""" |
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__author__ = "Dan Gezelter (gezelter@nd.edu)" |
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__version__ = "$Revision: 1665 $" |
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__date__ = "$Date: 2011-12-08 15:25:26 -0400 (Thu, 9 December 2011) $" |
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__copyright__ = "Copyright (c) 2007 by the University of Notre Dame" |
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__license__ = "OpenMD" |
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import sys |
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import getopt |
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import string |
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import math |
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def usage(): |
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print __doc__ |
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def readStatFile(statFileName): |
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global time |
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global temperature |
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global pressure |
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global volume |
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global Sx |
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global Sy |
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global Sz |
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time = [] |
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temperature = [] |
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pressure = [] |
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volume = [] |
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Sx = [] |
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Sy = [] |
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Sz = [] |
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statFile = open(statFileName, 'r') |
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line = statFile.readline() |
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print "reading File" |
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pressSum = 0.0 |
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volSum = 0.0 |
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tempSum = 0.0 |
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line = statFile.readline() |
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while 1: |
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L = line.split() |
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time.append(float(L[0])) |
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temperature.append(float(L[4])) |
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# |
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# OpenMD prints out pressure in units of atm. |
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# |
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pressure.append(float(L[5])) |
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volume.append(float(L[6])) |
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# |
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# OpenMD prints out heatflux in units of kcal / (mol s Ang^2). |
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# |
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Sx.append(float(L[8])) |
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Sy.append(float(L[9])) |
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Sz.append(float(L[10])) |
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line = statFile.readline() |
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if not line: break |
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statFile.close() |
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def computeAverages(): |
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global tempAve |
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global pressAve |
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global volAve |
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global pvAve |
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print "computing Averages" |
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tempSum = 0.0 |
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pressSum = 0.0 |
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volSum = 0.0 |
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pvSum = 0.0 |
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temp2Sum = 0.0 |
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press2Sum = 0.0 |
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vol2Sum = 0.0 |
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pv2Sum = 0.0 |
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# converts amu*fs^-2*Ang^-1 -> atm |
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pressureConvert = 1.63882576e8 |
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for i in range(len(time)): |
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tempSum = tempSum + temperature[i] |
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pressSum = pressSum + pressure[i] |
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volSum = volSum + volume[i] |
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# in units of amu Ang^2 fs^-1 |
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pvTerm = pressure[i]*volume[i] / pressureConvert |
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pvSum = pvSum + pvTerm |
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temp2Sum = temp2Sum + math.pow(temperature[i],2) |
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press2Sum = press2Sum + math.pow(pressure[i],2) |
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vol2Sum = vol2Sum + math.pow(volume[i],2) |
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pv2Sum = pv2Sum + math.pow(pvTerm,2) |
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tempAve = tempSum / float(len(time)) |
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pressAve = pressSum / float(len(time)) |
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volAve = volSum / float(len(time)) |
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pvAve = pvSum / float(len(time)) |
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tempSdev = math.sqrt(temp2Sum / float(len(time)) - math.pow(tempAve,2)) |
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pressSdev = math.sqrt(press2Sum / float(len(time)) - math.pow(pressAve,2)) |
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if (vol2Sum / float(len(time)) < math.pow(volAve,2)): |
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volSdev = 0.0 |
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else: |
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volSdev = math.sqrt(vol2Sum / float(len(time)) - math.pow(volAve,2)) |
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pvSdev = math.sqrt(pv2Sum / float(len(time)) - math.pow(pvAve,2)) |
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print " Average pressure = %f +/- %f (atm)" % (pressAve, pressSdev) |
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print " Average volume = %f +/- %f (Angst^3)" % (volAve, volSdev) |
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print "Average temperature = %f +/- %f (K)" % (tempAve, tempSdev) |
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print " Average PV product = %f +/- %f (amu Angst^2 fs^-1)" % (pvAve, pvSdev) |
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def computeCorrelations(outputFileName): |
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# converts amu*fs^-2*Ang^-1 -> atm |
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pressureConvert = 1.63882576e8 |
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# converts Ang^-3 * kcal/mol * Ang / fs to m^-3 * J/mol * m /s (= W / mol m^2) |
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heatfluxConvert = 4.187e38 |
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# converts fs to s |
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dtConvert = 1e-15 |
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# Boltzmann's constant amu*Ang^2*fs^-2/K |
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kB = 8.31451e-7 |
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# converts Ang^3 / (amu*Ang^2*fs^-2/K * K^2) -> m s^2 / (kg K^2) |
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thcondConvert = 6.0224e-14 |
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preV = thcondConvert * volAve / (kB * tempAve * tempAve) |
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if doEinstein: |
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print "computing Einstein-style Correlation Function" |
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# Precompute sum variables to aid integration. |
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# The integral from t0 -> t0 + t can be easily obtained |
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# from the precomputed sum variables: sum[t0+t] - sum[t0-1] |
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for i in range(1, len(time)): |
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xSum = [] |
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xSum.append(Sx[0]) |
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ySum = [] |
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ySum.append(Sy[0]) |
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zSum = [] |
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zSum.append(Sz[0]) |
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for i in range(1, len(time)): |
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xSum.append(xSum[i-1] + Sx[i]) |
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ySum.append(ySum[i-1] + Sy[i]) |
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zSum.append(zSum[i-1] + Sz[i]) |
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dt = time[1] - time[0] |
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eXcorr = [] |
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eYcorr = [] |
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eZcorr = [] |
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# i corresponds to the total duration of the integral |
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for i in range(len(time)): |
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xIntSum = 0.0 |
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yIntSum = 0.0 |
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zIntSum = 0.0 |
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# j corresponds to the starting point of the integral |
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for j in range(len(time) - i): |
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if (j == 0): |
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xInt = dt*xSum[j+i] |
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yInt = dt*ySum[j+i] |
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zInt = dt*zSum[j+i] |
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else: |
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xInt = dt*(xSum[j+i] - xSum[j-1]) |
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yInt = dt*(ySum[j+i] - ySum[j-1]) |
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zInt = dt*(zSum[j+i] - zSum[j-1]) |
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xIntSum = xIntSum + xInt*xInt |
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yIntSum = yIntSum + yInt*yInt |
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zIntSum = zIntSum + zInt*zInt |
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eXcorr.append(xIntSum / float(len(time)-i)) |
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eYcorr.append(yIntSum / float(len(time)-i)) |
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eZcorr.append(zIntSum / float(len(time)-i)) |
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outputFile = open(outputFileName, 'w') |
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for i in range(len(time)): |
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if doEinstein: |
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outputFile.write("%f\t%13e\n" % (time[i], 0.5 * preV * heatfluxConvert * heatfluxConvert * dtConvert * dtConvert * (eXcorr[i] + eYcorr[i] + eZcorr[i])) |
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outputFile.close() |
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def main(argv): |
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global doEinstein |
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global haveStatFileName |
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global haveOutputFileName |
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haveStatFileName = False |
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haveOutputFileName = False |
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doEinstein = False |
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try: |
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opts, args = getopt.getopt(argv, "hgesf:o:", ["help", "einstein", "stat-file=", "output-file="]) |
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except getopt.GetoptError: |
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usage() |
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sys.exit(2) |
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for opt, arg in opts: |
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if opt in ("-h", "--help"): |
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usage() |
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sys.exit() |
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elif opt in ("-e", "--einstein"): |
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doEinstein = True |
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elif opt in ("-f", "--stat-file"): |
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statFileName = arg |
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haveStatFileName = True |
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elif opt in ("-o", "--output-file"): |
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outputFileName = arg |
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haveOutputFileName = True |
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if (not haveStatFileName): |
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usage() |
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print "No stat file was specified" |
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sys.exit() |
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if (not haveOutputFileName): |
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usage() |
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print "No output file was specified" |
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sys.exit() |
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readStatFile(statFileName); |
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computeAverages(); |
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computeCorrelations(outputFileName); |
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if __name__ == "__main__": |
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if len(sys.argv) == 1: |
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usage() |
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sys.exit() |
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main(sys.argv[1:]) |