Python – partial string formatting

pythonstring-formatting

Is it possible to do partial string formatting with the advanced string formatting methods, similar to the string template safe_substitute() function?

For example:

s = '{foo} {bar}'
s.format(foo='FOO') #Problem: raises KeyError 'bar'

Best Answer

If you know in what order you're formatting things:

s = '{foo} {{bar}}'

Use it like this:

ss = s.format(foo='FOO') 
print ss 
>>> 'FOO {bar}'

print ss.format(bar='BAR')
>>> 'FOO BAR'

You can't specify foo and bar at the same time - you have to do it sequentially.

Related Solutions

Python – Calling a function of a module by using its name (a string)

Assuming module foo with method bar:

import foo
method_to_call = getattr(foo, 'bar')
result = method_to_call()

You could shorten lines 2 and 3 to:

result = getattr(foo, 'bar')()

if that makes more sense for your use case.

You can use getattr in this fashion on class instance bound methods, module-level methods, class methods... the list goes on.

Python – Convert bytes to a string

You need to decode the bytes object to produce a string:

>>> b"abcde"
b'abcde'

# utf-8 is used here because it is a very common encoding, but you
# need to use the encoding your data is actually in.
>>> b"abcde".decode("utf-8") 
'abcde'

Best Answer

Related Solutions

Python – Calling a function of a module by using its name (a string)

Python – Convert bytes to a string

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