CODEWITHSUNDEEP
python
derek73
derek73

Reputation: 5672

Conditionally including additional characters using python string formatting

Is it possible using python's string format to conditionally include additional characters along with the string variable only if the variable is not empty?

>>> format_string = "{last}, {first}"
>>> name = {'first': 'John', 'last':'Smith'}
>>> format_string.format(**name)
'Smith, John' # great!
>>> name = {'first': 'John', 'last':''}
>>> format_string.format(**name)
', John' # don't want the comma and space here, just 'John'

I would like to use the sameformat_string variable to handle any combination of empty or non-empty values for first or last in the name dict.

What's the easiest way to do this in python?

Upvotes: 3

Views: 350

Answers (3)

Kamil Pawłowski
Kamil Pawłowski

Reputation: 176

You can set value for separator based on condition.

'{first}{separator}{last}'.format(**{"first":first, "last":last,"separator":(", " if last and first else "")})

Upvotes: 1

Aamir Rind
Aamir Rind

Reputation: 39669

Why don't you use strip():

>>> format_string = "{last}, {first}"
>>> name = {'first': 'John', 'last':''}
>>> format_string.format(**name).strip(', ')
>>> 'John'

Upvotes: 6

johntellsall
johntellsall

Reputation: 15170

You could run the original dict through a function to 'clean' it, adding commas where appropriate. Or, have a defaultdict.

The following solution, the simplest, does a post-process step to remove any extra commas and spaces:

source

import re

name = {'first': 'John', 'last':''}
format_string = '{last}, {first}'

def fixme(instr):
    return re.sub('^, ', '',
                  re.sub(', $', '',
                         instr))

print fixme(format_string.format(**dict(first='John', last='')))
print
print fixme(format_string.format(**dict(first='', last='Smith')))

output

John

Smith

Upvotes: 0

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