CODEWITHSUNDEEP
python
Apollo
Apollo

Reputation: 9054

single line if statement - Python

I have

if board[a][b] == 0:
     board[a][b] = chr(current_char)

I want to refactor into one line. Something like the following:

board[a][b] = chr(current_char) if board[a][b] == 0

It seems that the closest I can come to this is 

board[a][b] = chr(current_char) if board[a][b] == 0 else board[a][b]

But the else clause seems redundant. Is there a stylistically better way to accomplish this?

Upvotes: 2

Views: 527

Answers (4)

Ganesh Kamath - 'Code Frenzy'
Ganesh Kamath - 'Code Frenzy'

Reputation: 5291

You can do this in Python:

if board[a][b] == 0: board[a][b] = chr(current_char)

if all you intend is to put this in one line.

Upvotes: 2

Fred Mitchell
Fred Mitchell

Reputation: 2161

Your two line version is easily the clearest. Stick with it.

>>> board[a][b] = board[a][b] or chr(current_char)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: an integer is required

What just happened here? If your manager wrote it, you want to find a new manager. If you did, maybe your manager will be looking for a new employee, since the program crashed while you were on vacation.

Upvotes: -1

kojiro
kojiro

Reputation: 77107

Oldschool Python had a trick for doing the ternary before Python had a ternary operator. Actually, this trick will work in many programming languages. I'm only going to tell you if you promise not to use it.

Promise?

[val_if_false, val_if_true][bool(condition)]

OK, now Python has a ternary, which looks like

val_if_true if condition else val_if_false

But even that is kinda sloppy. If you really want a one liner, make a function.

def val():
    if condition:
        return val_if_true
    else:
        return val_if_false

Your specific case is a little more specialized, since you want the else to be the original value. You could do

box[a][b] = box[a][b] or chr(current_char)

But again, the if statement is just more readable and clear as to the intent.

Upvotes: 7

user1902824
user1902824

Reputation:

A more "Pythonic" way of doing this type of thing is:

board[a][b] = board[a][b] or chr(current_char)

Upvotes: 2

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