Multiple increment operators on the same line Python

Question

Is it possible to do multiple variable increments on the same line in Python?

Example:

value1, value2, value3 = 0
value4 = 100
value1, value2, value3 += value4

In my real program I have LOTS of variables that are different but must all be added on with a single variable at one point.

What I am currently doing that I wanted this to replace:

value1 += value4
value2 += value4
value3 += value4
...
value25 += value4

Bhutan

Why don't u use list instead or dict? – Kosygin

value1, value2, value3 = (v + value4 for v in (value1, value2, value3))... – Moina

Answer 1

You can create special function for it:

def inc(value, *args):
    for i in args:
        yield i+value

And use it:

value1 = value2 = value3 = 0
value4 = 100
value1, value2, value3 = inc(value4, value1, value2, value3)

Servant

This is an interesting way to do it, however still very long to type. – Bhutan

Answer 2

Tuple and generator unpacking can be useful here:

value1, value2, value3 = 0, 0, 0
value4 = 100
value1, value2, value3 = (value4 + x for x in (value1, value2, value3))

Kaciekacy

@MikeMüller, that's not tuple unpacking, that's iterable unpacking of a generator expression. – Countercharge

@MikeGraham Thanks for the pointer. My wording is not totally correct. In the last line no tuple is created. Fixed. I used tuple unpacking for the more general iterable unpacking. – Nathalie

Answer 3

You can update the variables through the dictionary of the current namespace (e.g. vars()):

>>> value1 = value2 = value3 = 0
>>> value4 = 100
>>> for varname in ("value1", "value2", "value3"):
...     vars()[varname] += value4
... 
>>> value1, value2, value3
(100, 100, 100)

Execute

Answer 4

There is an easy way by making a list and looping over it:

value1, value2, value3 = 0
value4 = 100
valuelist = [value1, value2, value3]
for x in valuelist:
    x += value4

Lolalolande

That doesn't work -- ints are immutable, += rebinds the name, not mutates the value – Countercharge

@MikeGraham Then what would be mutable? Maybe converting value1-3 to these mutable values inside the list may work. – Lolalolande

the solution is just not to try to use mutation here, but rather create and assign new values. https://mcmap.net/q/1984073/-multiple-increment-operators-on-the-same-line-python was a pretty reasonable solution – Countercharge