Indentation of IF-ELSE block in python

Question

Hi I am python newbie and I am working on NLP using python. I am having a error in writing if-else block in python. When I am writing only if block at that time it is workin

Answer 1

I don't agree entirely with the accepted answer. Yes, indention is very important in Python but to state that the if-else has to always look like that with this formatting is a little bit overboard.

Python allows you a one-liners (even multiple) as long as you don't do anything fancy in there that requires indention in thebody of the if, elif or else.

Here are some examples:

choice = 1
# if with one-liner
if choice == 1: print('This is choice 1')

# if-else with one-liners
if choice == 1: print('This is choice 1')
else: print('This is a choice other than 1')

# if-else if with one-liners
if choice == 1: print('This is choice 1')
elif choice == 2: print('This is choice 2')

# if-else if-else with one-liners
if choice == 1: print('This is choice 1')
elif choice == 2: print('This is choice 2')
else: print('This is a choice other than 1 and 2')

# Multiple simple statements on a single line have to be separated by a semicolumn (;) except for the last one on the line
if choice == 1: print('First statement'); print('Second statement'); print('Third statement')

Usually it is not recommended to pack too many statements on a single line because then you loose one of the big features of Python - readability of the code.

Notice also that the above examples can also easily be applied to for and while. You can go even further as to do some crazy nesting of one-liner if blocks if you use the ternary conditional operator.

Here is how the operator usually looks:

flag = True
print('Flag is set to %s' % ('AWESOME' if True else 'BORING'))

What this does is basically create a simple if-else statement. You can embed it with one of your one-liners if you need more branching (but not complex one).

Hope this clarifies the situation a bit and what is allowed and not allowed. ;)