Found this code to solve transportation problem using Vogel's approximation. My goal is to modify it to accept input from a user but, my understanding of dictionary in python is quite weak. Hence any suggestion would be appreciated.

from collections import defaultdict
 
costs  = {'W': {'A': 16, 'B': 16, 'C': 13, 'D': 22, 'E': 17},
          'X': {'A': 14, 'B': 14, 'C': 13, 'D': 19, 'E': 15},
          'Y': {'A': 19, 'B': 19, 'C': 20, 'D': 23, 'E': 50},
          'Z': {'A': 50, 'B': 12, 'C': 50, 'D': 15, 'E': 11}}
demand = {'A': 30, 'B': 20, 'C': 70, 'D': 30, 'E': 60}
cols = sorted(demand.iterkeys())
supply = {'W': 50, 'X': 60, 'Y': 50, 'Z': 50}
res = dict((k, defaultdict(int)) for k in costs)
g = {}
for x in supply:
    g[x] = sorted(costs[x].iterkeys(), key=lambda g: costs[x][g])
for x in demand:
    g[x] = sorted(costs.iterkeys(), key=lambda g: costs[g][x])
 
while g:
    d = {}
    for x in demand:
        d[x] = (costs[g[x][1]][x] - costs[g[x][0]][x]) if len(g[x]) > 1 else costs[g[x][0]][x]
    s = {}
    for x in supply:
        s[x] = (costs[x][g[x][1]] - costs[x][g[x][0]]) if len(g[x]) > 1 else costs[x][g[x][0]]
    f = max(d, key=lambda n: d[n])
    t = max(s, key=lambda n: s[n])
    t, f = (f, g[f][0]) if d[f] > s[t] else (g[t][0], t)
    v = min(supply[f], demand[t])
    res[f][t] += v
    demand[t] -= v
    if demand[t] == 0:
        for k, n in supply.iteritems():
            if n != 0:
                g[k].remove(t)
        del g[t]
        del demand[t]
    supply[f] -= v
    if supply[f] == 0:
        for k, n in demand.iteritems():
            if n != 0:
                g[k].remove(f)
        del g[f]
        del supply[f]
 
for n in cols:
    print "\t", n,
print
cost = 0
for g in sorted(costs):
    print g, "\t",
    for n in cols:
        y = res[g][n]
        if y != 0:
            print y,
        cost += y * costs[g][n]
        print "\t",
    print
print "\n\nTotal Cost = ", cost

[url]http://rosettacode.org/wiki/Vogel's_approximation_method#Python[/url]

Didn't understand a thing, walks out of thread confused

http://rosettacode.org/wiki/Vogel's_approximation_method#Python

Eminya:
Didn't understand a thing, walks out of thread confused

What's so confusing?

Eminya:
Didn't understand a thing, walks out of thread confused

same same.

dozies1, what is your point? do you go about posting un-commented source codes with non-existent titles?

What does the code do and whwt problem do you have with it?

Sorry about that. I mistakenly deleted my question while modifying my post

lordZOUGA:
dozies1, what is your point? do you go about posting un-commented source codes with non-existent titles?

What does the code do and whwt problem do you have with it?

sorry about that

prowlerovervoid:

same same.

basically i want turn the keys and values of this:

costs  = {'W': {'A': 16, 'B': 16, 'C': 13, 'D': 22, 'E': 17},
          'X': {'A': 14, 'B': 14, 'C': 13, 'D': 19, 'E': 15},
          'Y': {'A': 19, 'B': 19, 'C': 20, 'D': 23, 'E': 50},
          'Z': {'A': 50, 'B': 12, 'C': 50, 'D': 15, 'E': 11}}
demand = {'A': 30, 'B': 20, 'C': 70, 'D': 30, 'E': 60}

supply = {'W': 50, 'X': 60, 'Y': 50, 'Z': 50}

to user input

dozies1:
basically i want turn the keys and values of this:

to user input

user input? how? to what function?

use the raw_input function and assign it to a variable then use the variable as the key to your dictionary as in
MyKey = raw_input('enter your key')
MyDict = {MyKeywhatever you want here)}

you should give a good description of what you're trying to achieve if you don't mind. there should be a better way out rather than this

dozies1:
basically i want turn the keys and values of this:

to user input

Does the user already know the value of the keys? for example does the user already know that 'W' matches this: {'A': 16, 'B': 16, 'C': 13, 'D': 22, 'E': 17}?

if not you probably should show them the table once they start the program.

if they do, you just have to accept whatever input they provide verify it and match it to the table and then compute.

for example:

#based on python3

print("Please input a cost: "
cost = input()
if cost and type(cost) is str and cost in costs.keys():
    #do stuff with cost possible retrieve it's value from the dictionary
    print(costs[cost])

Thanks for your contribution

KelvinMega:
use the raw_input function and assign it to a variable then use the variable as the key to your dictionary as in
MyKey = raw_input('enter your key')
MyDict = {MyKeywhatever you want here)}

you should give a good description of what you're trying to achieve if you don't mind. there should be a better way out rather than this

I'm trying to write a program that solves transportation problem this way

Vogel's Approximation Method of Allocation.
This method also takes costs into account in
allocation. Five steps are involved in applying
this heuristic:
Step 1: Determine the difference between the
lowest two cells in all rows and columns,
including dummies.
Step 2: Identify the row or column with the
largest difference. Ties may be broken arbitrarily.
Step 3: Allocate as much as possible to the
lowest-cost cell in the row or column with the
highest difference. If two or more differences
are equal, allocate as much as possible to the
lowest-cost cell in these rows or columns.
Step 4: Stop the process if all row and column
requirements are met. If not, go to the next
step.
Step 5: Recalculate the differences between the
two lowest cells remaining in all rows and
columns. Any row and column with zero supply
or demand should not be used in calculating
further differences. Then go to Step 2.

http://orms.pef.czu.cz/text/VogelAproxim.html

lordZOUGA:


Does the user already know the value of the keys? for example does the user already know that 'W' matches this: {'A': 16, 'B': 16, 'C': 13, 'D': 22, 'E': 17}?

if not you probably should show them the table once they start the program.

if they do, you just have to accept whatever input they provide verify it and match it to the table and then compute.

for example:

#based on python3

print("Please input a cost: "
cost = input()
if cost and type(cost) is str and cost in costs.keys():
    #do stuff with cost possible retrieve it's value from the dictionary
    print(costs[cost])

Thanks.
The user wouldn't know. I would try your suggestion.