syntax-error: can't assign to operator

问题

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.

回答1:

Python is upset because you are attempting to assign a value to something that can't be assigned a value.

((t[1])/length) * t[1] += string

When you use an assignment operator, you assign the value of what is on the right to the variable or element on the left. In your case, there is no variable or element on the left, but instead an interpreted value: you are trying to assign a value to something that isn't a "container".

Based on what you've written, you're just misunderstanding how this operator works. Just switch your operands, like so.

string += str(((t[1])/length) * t[1])

Note that I've wrapped the assigned value in str in order to convert it into a str so that it is compatible with the string variable it is being assigned to. (Numbers and strings can't be added together.)

回答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].

回答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.)

回答4:

In case it helps someone, if your variables have hyphens in them, you may see this error since hyphens are not allowed in variables names in Python and are used as subtraction operators.

Example:

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

回答5:

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.

回答6:

in python only work

a=4
b=3

i=a+b

which i is new operator

来源：https://stackoverflow.com/questions/8956825/syntax-error-cant-assign-to-operator

标签

python

syntax-error