>> dictionary-key/value syntax), you can do something like:
>>>>> number = lambda x: dict((str(i+1), v) for (i,v) in enumerate(x))
>>>>> "%(2)s and %(1)s" % number(["A", "B"])
>
> Whoa - that'll take me a little while to figure out, but it looks intriguing!
It basically just returns a dictionary that maps your
positional-index of your input to your input. Because keyword
substitution looks up a string in your dict, you have to convert
the index to a string. And since you were using one-based
indexing rather than zero-based indexing, I added one to the
index before converting it to a string. To help understand it,
watch each of the pieces in that function:
>>> for z in enumerate(x): print z
>>> for z in ((i+1, v) for v in enumerate(x)): print z
>>> for z in ((str(i+1), v) for v in enumerate(x)): print z
>>> print number(["h","e","l", "l", "o"])
so you can see what's getting passed to the string-formatter.
If you're passing in a fixed parameter list (one that you
generate right there in the code, rather than some list you've
previously built up and would use with something like
"number(some_list)"), you can insert an asterisk between the
"lambda x"
>>> number = lambda *x: dict((str(i+1), v) for (i,v) in enumerate(x))
so it can be called a little more cleanly without the extra
"list'ification" like
>>> "%(2)s and %(1)s" % number("A", "B")
It just depends on what your common case is.
-tkc
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