I have a string like below:
a = "This is {} code {}"
In later part of my code, I will be formatting the string using args provided to the below function:
def format_string(str, *args):
fmt_str = str.format(*args)
print fmt_str
...
My problem here is that if number of args provided to the function format_string
is either lesser or more than the required, I get an Exception. Instead, if args are less, I want it to print empty {} and if the args are more than required, then I want the extra args to be ignored. i have tried to do this is several ways, but could not avoid the exception. Can anyone help please?
Update: I was able to fix this problem based on the answer provided in this post: Leaving values blank if not passed in str.format
This is my implementation:
class BlankFormatter(Formatter):
def __init__(self, default=''):
self.default = default
def get_value(self, key, args, kwargs):
if isinstance(key, (int, long)):
try:
return args[key]
except IndexError:
return ""
else:
return kwargs[key]
Had to modify the string as follows to use the above BlankFormatter on it:
a = "This is {0} code {1}"
In my format_string function, I used the BlankFormatter to format the string:
def format_string(str, *args):
fmt = BlankFormatter()
fmt_str = fmt.format(str,*args)
print fmt_str
...
There are a few different ways to do this, some of which are more or less flexible. Perhaps something like this will work for you:
from __future__ import print_function
def transform_format_args(*args, **kwargs):
num_args = kwargs['num_args'] # required
filler = kwargs.get('filler', '') # optional; defaults to ''
if len(args) < num_args: # If there aren't enough args
args += (filler,) * (num_args - len(args)) # Add filler args
elif len(args) > num_args: # If there are too many args
args = args[:num_args] # Remove extra args
return args
args1 = transform_format_args('cool', num_args=2)
print("This is {} code {}.".format(*args1)) # This is cool code .
args2 = transform_format_args('bird', 'worm', 'fish', num_args=2)
print("The {} ate the {}.".format(*args2)) # The bird ate the worm.
args3 = transform_format_args(num_args=3, filler='thing')
print("The {} stopped the {} with the {}.".format(*args3))
# The thing stopped the thing with the thing.
num_args
is the number of args
you want, not the number that you passed in. filler
is what to use when there aren't enough args
.
def formatter(input, *args):
format_count = input.count("{}")
args = list(args) + ["{}"] * (format_count - len(args))
print input.format(*args[:format_count])
formatter("{} {} {}", "1", "2")
formatter("{} {} {}", "1", "2", "3")
formatter("{} {} {}", "1", "2", "3", "4")
1 2 {}
1 2 3
1 2 3
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