CODEWITHSUNDEEP
pythonstringstring-formatting
RadiantHex
RadiantHex

Reputation: 25547

Advanced string formatting - Python

here is a quick example of what I'm trying to do

box = {
    'colour': 'Red',
    'dimensions': {
        'width': '100px',
        'height': '333px',
     }
}

print "The box is %(colour)s, wide %(dimensions.width) and high %(dimensions.height)" %box

Is this possible with the standard library?

If not, what libraries would you recommend?

Upvotes: 3

Views: 3478

Answers (6)

NuclearPeon
NuclearPeon

Reputation: 6039

In an object oriented manner, you could have Box as an object and then override the __str__() and __unicode__() methods to print out the variables such as width and colour in a human-readable string.

Example:

class Box():
    def __init__(self, **kwargs):
        self.dimensions = (kwargs.get('width'), kwargs.get('height'),)
        self.colour = kwargs.get('colour')

    def __str__(self):
        return 'The box is {}, wide {}, and {} height'.format(
            self.dimensions[0], self.dimensions[1], self.colour)

and here is how you initiate the class:

a = Box(height='100px', width='100px', colour='Red')

and this is how you print it out:

print(a)

or

myvar = str(a)

Note: I put width and height in a tuple.

Upvotes: 0

Andrew Clark
Andrew Clark

Reputation: 208405

Here is the solution I came up with, although the str.format methods are probably cleaner, add the following function and then use "...format string..." % flatten(box).

def flatten(d, key=None):
    r = d.copy()
    if key is not None:
        r = dict((key+"."+k, v) for k, v in r.iteritems())
    for k, v in r.items():
        if isinstance(v, dict):
            r.update(flatten(v, k))
            del r[k]
    return r

Here is an example:

>>> flatten(box)
{'dimensions.width': '100px', 'colour': 'Red', 'dimensions.height': '333px'}
>>> print "The box is %(colour)s, wide %(dimensions.width)s and high %(dimensions.height)s" % flatten(box)
The box is Red, wide 100px and high 333px

Upvotes: -1

defuz
defuz

Reputation: 27581

Yes, but unfortunately only for Python3

http://docs.python.org/release/3.0.1/whatsnew/2.6.html#pep-3101

Edit:

Sorry, this feature also ported in python 2:

>>> import sys
>>> print 'Platform: {0.platform}\nPython version: {0.version}'.format(sys)
Platform: linux2
Python version: 2.7.1+ (r271:86832, Apr 11 2011, 18:05:24) 
[GCC 4.5.2]

Upvotes: 0

Fredrik Pihl
Fredrik Pihl

Reputation: 45634

...also, have a look at string templates, been around since 2.4

Example

>>> from string import Template
>>> s = Template('$who likes $what')
>>> s.substitute(who='tim', what='kung pao')
'tim likes kung pao'
>>> d = dict(who='tim')
>>> Template('Give $who $100').substitute(d)
Traceback (most recent call last):
[...]
ValueError: Invalid placeholder in string: line 1, col 10
>>> Template('$who likes $what').substitute(d)
Traceback (most recent call last):
[...]
KeyError: 'what'
>>> Template('$who likes $what').safe_substitute(d)
'tim likes $what'

Upvotes: 2

sberry
sberry

Reputation: 131968

>>> box = {
        'colour': 'Red',
        'dimensions': {
            'width': '100px',
            'height': '333px',
         }
    }
>>> print "The box is {colour}, wide {dimensions[width]} and high {dimensions[height]}".format(**box)
The box is Red, wide 100px and high 333px

Upvotes: 10

Katriel
Katriel

Reputation: 123612

Yes. You've got it right, except that you should use {} instead of %().

Upvotes: 3

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