"Python Tour" chapter II (eight): Zip zip and map zipper

1.zip Zipper

• Function: Merge two lists into a list of elements as tuples;

• The demo is as follows:

>>> a = range (0,5) >>> B = Range (5,10) >>> a[0, 1, 2, 3, 4]>>> b[5, 6, 7, 8, 9]>>& Gt Zip (A, b) [(0, 5), (1, 6), (2, 7), (3, 8), (4, 9)]>>> Zip (b,a) [(5, 0), (6, 1), (7, 2), (8, 3), (9, 4)]

• If the number of two list elements is inconsistent, the zip is automatically ignored:

>>> a = range (1,5) >>> B = [' A ', ' B ', ' C ']>>> a[1, 2, 3, 4]>>> b[' A ', ' B ', ' C ']>> > Zip (b) [(1, ' a '), (2, ' B '), (3, ' C ')]

• Using the zip function, you can create a dictionary:

>>> key = [' name ', ' girlfriend ']>>> values = [' xpleaf ', ' CL ']>>> zip (key, values) [(' Name ', ' XP Leaf '), (' Girlfriend ', ' cl ')]>>> dict (Zip (key, values)) {' Girlfriend ': ' CL ', ' name ': ' Xpleaf '}>>> Dict (Zip (key, values))

2.map

The map function is very powerful, here only to mention its similar to the ZIP function;

>>> a = range (1,5) >>> B = [' A ', ' B ', ' C ', ' d ']>>> map (A, B) Traceback (most recent call last): F  Ile "<stdin>", line 1, in <module>typeerror: ' List ' object was not callable>>> map (none,a,b) [(1, ' a '), (2, ' B '), (3, ' C '), (4, ' d ')]

• You can see that the map needs to specify the first parameter, because map does not automatically ignore two different numbers of lists, specifying the parameters as padding for the list of insufficient numbers:

>>> B.pop () ' d ' >>> map (none, a, B) [(1, ' a '), (2, ' B '), (3, ' C '), (4, none)]

This article is from the "fragrant fluttering leaves" blog, please make sure to keep this source http://xpleaf.blog.51cto.com/9315560/1695709

"Python Tour" chapter II (eight): Zip zip and map zipper