# To compute the percentage increase in each crop over
# the period from 2007 to 2011.
# The output is written to an external file by opening
# a file and writing data to it. 
# The output file is : foodprod1.dat
# The input data file is : food.dat

import numpy as np

# Reads the names of crops.
crops = np.loadtxt('food.dat', dtype='str', skiprows=5, usecols=(0,))

# Reads data in columns 5 to 9
fdat = np.loadtxt('food.dat', skiprows=5, usecols=(5,6,7,8,9))


f=open('foodprod1.dat','w')          # This line opens a file for writing

for i in range(np.size(crops)):
  avginc = ( fdat[i][4] - fdat[i][0] )/5.0
  f.write("%14s %7.2f \n"%  (crops[i], avginc))

f.close()                            # This line closes the file