Don't introduce map(None, ...) in the tutorial. In practice, zip() is

usually preferred.
This commit is contained in:
Neil Schemenauer 2003-08-14 22:57:46 +00:00
parent e98147a8e5
commit 90b182c16c
1 changed files with 4 additions and 9 deletions

View File

@ -1836,19 +1836,14 @@ cubes:
More than one sequence may be passed; the function must then have as
many arguments as there are sequences and is called with the
corresponding item from each sequence (or \code{None} if some sequence
is shorter than another). If \code{None} is passed for the function,
a function returning its argument(s) is substituted.
Combining these two special cases, we see that
\samp{map(None, \var{list1}, \var{list2})} is a convenient way of
turning a pair of lists into a list of pairs. For example:
is shorter than another). For example:
\begin{verbatim}
>>> seq = range(8)
>>> def square(x): return x*x
>>> def add(x, y): return x+y
...
>>> map(None, seq, map(square, seq))
[(0, 0), (1, 1), (2, 4), (3, 9), (4, 16), (5, 25), (6, 36), (7, 49)]
>>> map(add, seq, seq)
[0, 2, 4, 6, 8, 10, 12, 14]
\end{verbatim}
\samp{reduce(\var{func}, \var{sequence})} returns a single value