How can I use the result from a function in another function?

Question

Suppose I have a function like:

def eklid(p, a, b,):
    x = [1, 0]
    y = [0, 1]
    r = [a, b]
    q = [0]
    n = 0
    while r[n+1] != 0:
        q.append(r[n] // r[n+1])
        r.append(r[n] % r[n+1])
        x.append(x[n] - x[n+1] * q[n+1])
        y.append(y[n] - y[n+1] * q[n+1])

        if p == 0:
            print(r[n], "=", r[n+1], "*", q[n+1], "+", r[n+2])
        elif p == 1:    # extended print
            print(r[n+2], "\t", x[n+2], "\t", y[n+2], "\t", r[n+2], "=", a, "*", x[n+2], "+", b, "*", y[n+2])
        elif p == -1:
            k =1
        else:
            print("wrong input")
        n += 1
    return x, y, r, q, n,

I want to use x and r from it in this function:

    def cong_solv(x, r, b,):
        result = x/r
        int_result = int(result)
        return int_result

How can I do that?

Answer 1

# Here, a=x, b=y, c=r, d=q, e=n
a, b, c, d, e = eklid(h, i, k)

# Assuming based on your function definitions you want the
# same value as the third argument
final_result = cong_solv(a, c, k)

You get the return values from eklid and save them into variables. You then use those variables to call the next function.

Of course, in a real code you should name your varialbes better than I did in this example. I deliberately did not call the variables the same names as inside the function to demonstrate that you don't have to.

Answer 2

One way would be to call the eklid() function from inside the cong_solv() function. Something like this should work:

def cong_solv(x, r, b):
   p = "foo"
   b = "bar"
   x, y, r, q, n = eklid(p, a, b)

   result = x/r 
   int_result = int(result) 
   return int_result

Answer 3

In python, when you return more than one variable, it returns a tuple. You can retrieve the value by its index (returned_value[0], returned_value[1]) or unpack the tuple like Mike Driscoll said (a, b, c, d = eklid(h, i, k)).

Since I got two downvotes, I am going to give you better (I hope) explanation: Everytime you return more than one value, it returns a tuple .

def my_function():
   a = 10
   b = 20
   return a, b

print type(my_function()) # <type 'tuple'>

But if you return just one value:

def my_function():
    a = 10
    return a

print type(my_function()) # <type 'int'>

So if you want to use your value, you can:

Unpack tuple values like this

a, b = my_function()

This way you get your return values in the same order you return inside my_function.

Rewriting your code, you can simply do:

a, b, c = eklid(10, 20, 30) # it will return a tuple

And call your other function:

cong_solv(a, b, 20)

In my honest opinion I would return a dict . With dict you can be explicit because your values have key names.

Inside your eklid return function:

return d # d = {"what_x_means": x,
         #      "what_y_means": y,
         #      "what_r_means": r,
         #      "what_q_means": q, 
         #      "what_n_means": n}

And retrieve for its key:

d["what_x_means"]
d["what_r_means"]

Answer 4

Similar to How do you return multiple values in Python?

1. Return as an tuple (x,y,r....) or an array and assign to tuple / array respectively.
2. Or assign them to class variables and access them