accessing dictionary values to work with module

[princessotes]

Hi, I'll try and explain my problem as simple as possible. I have written a module to perform a generalised operation (as shown below).

from math import sqrt
from math import pow
from math import log10
from Numeric import *
import numpy as np
def Entropy(parameters, temperature):
    t=float(temperature/1000.0)
    return (("%0.7f" %(float(A*log(t) + B*t + C*((pow(t,2.))/2.) + D*((pow(t,3.))/3.) - (E/(2.*(pow(t,2.)))) + G)/1000)))

The operation require values and I have put these into a dictionary in the running script (This is shown as well).

import thermodynamics
oxygen={'A':31.32234, 'B':-20.23531, 'C':57.86644, 'D':-36.50624, 'E':-0.007374, 'F':-8.903471, 'G':246.7945, 'H':0.000000,'EnthalpyTempZero':8.68, 'frequency':1580.19, 'EDFT':-4.9316435}
Oshomate= oxygen['A'], oxygen['B'], oxygen['C'],oxygen['D'], oxygen['E'],oxygen['F'],oxygen['G'],oxygen['H']
print EntropyO
EnthalpyEntropyO = thermodynamics.EnthalpyEntropy(EnthalpyO,oxygen['EnthalpyTempZero'], EntropyO, temperature)

When I run the scripts, it gives an error message "NameError: global name 'A' is not defined". How can I get the module to access the dictionary values in the running script?

[Stefano Mtangoo]

return (("%0.7f" %(float(A*log(t) + B*t + C*((pow(t,2.))/2.) + D*((pow(t,3.))/3.) - (E/(2.*(pow(t,2.)))) + G)/1000)))

I see A, B...et al included but what are they?
You need to define the like A = 2, B = "You"

[Stefano Mtangoo]

Big sign of business immaturity!

[jlm699]

import thermodynamics
oxygen={'A':31.32234, 'B':-20.23531, 'C':57.86644, 'D':-36.50624, 'E':-0.007374, 'F':-8.903471, 'G':246.7945, 'H':0.000000,'EnthalpyTempZero':8.68, 'frequency':1580.19, 'EDFT':-4.9316435}
Oshomate= oxygen['A'], oxygen['B'], oxygen['C'],oxygen['D'], oxygen['E'],oxygen['F'],oxygen['G'],oxygen['H']
print EntropyO
EnthalpyEntropyO = thermodynamics.EnthalpyEntropy(EnthalpyO,oxygen['EnthalpyTempZero'], EntropyO, temperature)

When I run the scripts, it gives an error message "NameError: global name 'A' is not defined". How can I get the module to access the dictionary values in the running script?

You'll need to pass the dictionary to your Entropy function in the module thermodynamics . Then within the function you simply do as you've done in the "running script":

oxygen['A']

This returns the value of the element with the key 'A' in the dictionary oxygen

[princessotes]

You'll need to pass the dictionary to a function in the module,

but how do I pass the dictionary to the module. is there a specific command to use.

[jlm699]

but how do I pass the dictionary to the module. is there a specific command to use.

I don't see your specific call to the thermodynamics.Entropy() function, but here are the basics for passing a variable to a function:

# First we define a function, you'll notice it has two parameters, var1 and var2
>>> def my_function(var1, var2):
...     print 'This is the first var:', var1
...     print 'This is the 2nd var:', var2
...     
# Now I'll create two arbitrary objects, a and d
>>> a = 5
>>> d = { 'a':1, 'b':2, 'c':3 }
# To pass these two objects to my_function, I place them in the parenthesis when calling it
>>> my_function(a,d)
This is the first var: 5
This is the 2nd var: {'a': 1, 'c': 3, 'b': 2}
# Now I'll redefine the function to specifically access an element in the dictionary that I passed
>>> def my_function(var1, var2):
...     print 'This is the first var:', var1
...     print 'This is the a element in var2:', var2['a']
...     
>>> my_function(a,d)
This is the first var: 5
This is the a element in var2: 1
>>>

So that's the basics. Now for your specific case, you'll either need to modify the definition of Entropy to specifically expect a dictionary for you to access, or you'll need to roll that dictionary into the parameters object that you pass to this function.

It all depends on your preference

[bumsfeld]

It's best to test the module first with something like this:

from math import pow
from math import log10

def get_entropy(d, t):
    """
    where d is the element's data dictionary and t is temperature
    """
    t = t/1000.0
    ent = (d['A']*log10(t) + d['B']*t + d['C']*pow(t,2.)/2. +
           d['D']*pow(t,3.)/3. - d['E']/(2.*(pow(t,2.))) +
           d['G'])/1000
    return "%0.7f" % ent

# test the module
if __name__ == '__main__':
    oxygen = {'A':31.32234, 'B':-20.23531, 'C':57.86644,
              'D':-36.50624, 'E':-0.007374, 'F':-8.903471,
              'G':246.7945, 'H':0.000000,
              'EnthalpyTempZero':8.68,
              'frequency':1580.19, 'EDFT':-4.9316435}
    t = oxygen['EnthalpyTempZero']
    entropy = get_entropy(oxygen, t)
    print(entropy)