+= and -= expressions in Python (?)

Question

I am trying to follow the example in this post, and it was going smoothly until I ran into the lines of code with -= and += calls.

I believe this might be some sort of misprint in expressions that are supposed to update the object on the RHS of = according to some condition.

Unfortunately, interpreting this expression is key in getting what the code is doing, and guessing defeats the purpose.

Do these fragments of code or operators make any sense?

What was intended by the author?

It is not a misprint, `-=` & `+=` are standard operators of the theme `=`. — shad0w_wa1k3r, Mar 19 '17 at 19:12

score 2 · Accepted Answer · answered Mar 19 '17 at 19:13

2

x -= y, x += y and so forth are a shorthand way of writing x = x - y and x = x + y respectively.

answered Mar 19 '17 at 19:13

bigsim

score 0 · Answer 2 · answered Mar 19 '17 at 19:12

0

These are shorthands.

a -= b

means

a = a -b

The meaning of += should be fathomable now.

But, it seems that you might have gotten some Exception. In that case, feel free to post it, and your code.

answered Mar 19 '17 at 19:12

serv-inc

2 Answers2