Variables that have been assigned in a line.split() command, are not read into a function

Question

In this code the variables pressure and enthalpy, that come from a [float(n) for n in line.split()] command, are not read into a function:

import numpy as np

pressure_gibbs = open('pressure_gibbs_all_points.dat', 'w')

pressure_gibbs.write('#pressure    gibbs\n')

## FUNCTIONS:

def G(H,S):
# G = H - TS 
# Then:
  gibbs = H - 298.15 * S/4.0
  return gibbs



with open('entropies_parsed.dat') as entropies_parsed, open('pressure_enthalpy_all_points.dat') as enthalpy_pressure:  # open the file
  entropies_parsed.next() # skip the first line
  enthalpy_pressure.next()

  entropy = [float(line) for line in entropies_parsed]
  #print entropy
  for line in enthalpy_pressure:
       #print entropy
        pressure, enthalpy = [float(n) for n in line.split()]
        #print pressure
        #print enthalpy
        for i in entropy:
            #print i
            gibbs = G(enthalpy, i)
            #print gibbs
            pressure_gibbs.write('{}\t{}\n'.format (pressure, gibbs))

pressure_gibbs.close()

Only two files in this folder are necessary to run this code:

pressure_enthalpy_all_points.dat:

# pressure enthalpy
2         3
5         4
3.5       2

entropies_parsed.dat:

# entropies
0.5        
0.2        
0.47       

This is the best I could achieve, and the indentation position is right, from my knowledge.

However, this code gives a file, pressure_gibbs_all_points.dat:

#pressure    gibbs
2.0     -34.26875
2.0     -11.9075
2.0     -32.032625
5.0     -33.26875
5.0     -10.9075
5.0     -31.032625
3.5     -35.26875
3.5     -12.9075
3.5     -33.032625

which is wrong.

I would appreciate if you could help me please.

Answer 1

your output file seems to show values that match the math in your code, so the only thing I can see is that you have 9 calculations where you were expecting 3. This is because you have a nested loop, so you are first looping over pressure, and and then looping over entropy. So you calculate Gibbs for 3 values of entropy at p = 2.0, then again for p = 5.0, and finally for p = 3.5, so you have 9 calculations. If you are only looking for 3 calculations:

for i, line in zip(entropy, enthalpy_pressure):
    #print entropy
    pressure, enthalpy = [float(n) for n in line.split()]
    #print pressure
    #print enthalpy
        #print i
    gibbs = G(enthalpy, i)
    #print gibbs
    pressure_gibbs.write('{}\t{}\n'.format (pressure, gibbs))