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?
>>> 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
. dot notation in your strings is really important to you then there is a way you can do that as well.
width and height need quotes around?An expression of the form '.name' selects the named attribute using getattr(), while an expression of the form '[index]' does an index lookup using __getitem__().Yes. You've got it right, except that you should use {} instead of %().
print('Hello {}, this is {}'.format('world', 'python')) Also see the webpage: http://docs.python.org/2/library/string.html...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'
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]
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.
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
