How to write shorter Python code with several if and else statements?

Question

How can you optimize the following code and write less?

class CleanItem():

   def process_item(self, item, spider):

      PSCV = str(item['page_source_canonical']).split("'")[1]

      if PSCV != "":
          if PSCV != item['page_source']:
              item['page_source_canonical_is_itself'] = False
          else:
              item['page_source_canonical_is_itself'] = True
      else:
              item['page_source_canonical_is_itself'] = True

    
      return item

First it checks if it is empty. If it is empty, it is true. If it is not empty it should be checked and if it is the same then again it is true. Otherwise it is false.

PSCV in ("", item['page_source']) gives you your desired boolean value directly. — jasonharper
– jasonharper, Commented Aug 16, 2022 at 21:50

Nimantha · Accepted Answer · 2025-07-19 12:14:22Z

5

You wrote

if PSCV != "":
    if PSCV != item['page_source']:
        item['page_source_canonical_is_itself'] = False
    else:
        item['page_source_canonical_is_itself'] = True
else:
        item['page_source_canonical_is_itself'] = True

You want

item['page_source_canonical_is_itself'] =  PSCV in (
    '', item['page_source'])

That's DRY, and very clearly spells out Author's Intent that we shall assign True upon matching either value, else False.

Style nit: PEP 8 asks that you spell it pscv, lowercase.

Consider deleting the unused spider parameter.

edited Jul 19 at 12:14

Nimantha

6,5376 gold badges32 silver badges78 bronze badges

answered Aug 16, 2022 at 21:53

J_H

21.3k5 gold badges29 silver badges51 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Sardar Over a year ago

What is this operator called? and do you have an educational resource?

J_H Over a year ago

I think you're referring to the in operator: docs.python.org/3/reference/expressions.html#in Also, linter documentation is here: flake8.pycqa.org/en/latest

Kudehinbu Oluwaponle Over a year ago

the "in" operator is used to check if an element is found in an iterable e.g a list, tuple. Here it is checking if PSCV is '' or item['page_source']

Sardar Over a year ago

@J_H Can you help with this question? stackoverflow.com/q/73389010/8519380

J_H Over a year ago

@zaki98's use of return request.replace(...) seems pretty relevant.

Nimantha · Accepted Answer · 2025-07-19 12:15:25Z

2

Yes, you could simplify:

if PSCV != "":
    if PSCV != item['page_source']:
        item['page_source_canonical_is_itself'] = False
    else:
        item['page_source_canonical_is_itself'] = True
else:
    item['page_source_canonical_is_itself'] = True

to:

if PSCV != "" and PSCV != item['page_source']:
    item['page_source_canonical_is_itself'] = False
else:
    item['page_source_canonical_is_itself'] = True

or even further to:

condition = PSCV != "" and PSCV != item['page_source']
item['page_source_canonical_is_itself'] = not condition

edited Jul 19 at 12:15

Nimantha

6,5376 gold badges32 silver badges78 bronze badges

answered Aug 16, 2022 at 21:49

Michael Hodel

3,0381 gold badge8 silver badges12 bronze badges

4 Comments

OneCricketeer Over a year ago

Or shorter... item['page_source_canonical_is_itself'] = PSCV == "" or PSCV == item['page_source']

Michael Hodel Over a year ago

@OneCricketeer That is indeed even shorter, but also 4 characters above the maximum line length of 79, as recommended by PEP

OneCricketeer Over a year ago

How about? = PSVC in ("", item['page_source'])

Michael Hodel Over a year ago

Good one, was also thinking about that, but I'd argue it's a tad bit less intuitive

Nimantha · Accepted Answer · 2025-07-19 12:15:40Z

1

if PSCV != "":
       if PSCV != item['page_source']:
           item['page_source_canonical_is_itself'] = False
       else:
           item['page_source_canonical_is_itself'] = True
   else:
           item['page_source_canonical_is_itself'] = True

If I wanted to refactor the code above, two options

The most explanatory (not necessarily the shortest):

if (PSCV == ""):
      item['page_source_canonical_is_itself'] = True
elif (PSCV == item['page_source']):
      item['page_source_canonical_is_itself'] = True
else:
      item['page_source_canonical_is_itself'] = False

The shorter - ternary:

item['page_source_canonical_is_itself'] = ( (PSCV == "") or (PSCV == item['page_source']) )? true: false

edited Jul 19 at 12:15

Nimantha

6,5376 gold badges32 silver badges78 bronze badges

answered Aug 16, 2022 at 22:13

Kudehinbu Oluwaponle

1,18513 silver badges11 bronze badges

Collectives™ on Stack Overflow

How to write shorter Python code with several if and else statements?

3 Answers 3

5 Comments

4 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

5 Comments

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related