SyntaxError: cannot assign to operator

Question

def RandomString (length,distribution):
    string = ""
    for t in distribution:
        ((t[1])/length) * t[1] += string
    return shuffle (string)

This returns a syntax error as described in the title. In this example, distribution is a list of tuples, with each tuple containing a letter, and its distribution, with all the distributions from the list adding up to 100, for example:

[("a",50),("b",20),("c",30)] 

And length is the length of the string that you want.

Answer 1

Make sure the variable does not have a hyphen (-).

Hyphens are not allowed in variable names in Python and are used as subtraction operators.

Example:

my-variable = 5   # would result in 'SyntaxError: can't assign to operator'

Answer 2

Well, as the error says, you have an expression (((t[1])/length) * t[1]) on the left side of the assignment, rather than a variable name. You have that expression, and then you tell Python to add string to it (which is always "") and assign it to... where? ((t[1])/length) * t[1] isn't a variable name, so you can't store the result into it.

Did you mean string += ((t[1])/length) * t[1]? That would make more sense. Of course, you're still trying to add a number to a string, or multiply by a string... one of those t[1]s should probably be a t[0].

Answer 3

Instead of ((t[1])/length) * t[1] += string, you should use string += ((t[1])/length) * t[1]. (The other syntax issue - int is not iterable - will be your exercise to figure out.)

Answer 4

What do you think this is supposed to be: ((t[1])/length) * t[1] += string

Python can't parse this, it's a syntax error.