[英]Extract x and y values from a list
I have list like this: 我有这样的列表:
pp=[[0,0] , [-1,5], [2,3], [1,5], [3,6], [4,5], [5,3], [8,-2], [4, -4], [2, -5]]
And I want to extract x and y values in separate lists like: 我想在单独的列表中提取x和y值,如:
ppx= [0, -1, 2, 1, 3, 4, 5, 8, 4, 2]
Use zip()
to separate the coordinates: 使用
zip()
分隔坐标:
ppx, ppy = zip(*pp)
This produces tuples; 这会产生元组; these are easily enough mapped to
list
objects: 这些很容易映射到
list
对象:
ppx, ppy = map(list, zip(*pp))
This works in both Python 2 and 3 (where the map()
iterator is expanded for the tuple assignment). 这适用于Python 2和3(其中
map()
迭代器被扩展用于元组赋值)。
Demo: 演示:
>>> pp=[[0,0] , [-1,5], [2,3], [1,5], [3,6], [4,5], [5,3], [8,-2], [4, -4], [2, -5]]
>>> ppx, ppy = zip(*pp)
>>> ppx
(0, -1, 2, 1, 3, 4, 5, 8, 4, 2)
>>> ppy
(0, 5, 3, 5, 6, 5, 3, -2, -4, -5)
>>> ppx, ppy = map(list, zip(*pp))
>>> ppx
[0, -1, 2, 1, 3, 4, 5, 8, 4, 2]
>>> ppy
[0, 5, 3, 5, 6, 5, 3, -2, -4, -5]
I think that list comprehensions is the most straightforward way: 我认为列表推导是最直接的方式:
xs = [p[0] for p in pp]
ys = [p[1] for p in pp]
Use list comprehensions: 使用列表推导:
pp=[[0,0] , [-1,5], [2,3], [1,5], [3,6], [4,5], [5,3], [8,-2], [4, -4], [2, -5]]
ppx=[a[0] for a in pp]
ppy=[a[1] for a in pp]
More on list comprehensions in the Python docs: http://docs.python.org/2/tutorial/datastructures.html#list-comprehensions 有关Python文档中列表推导的更多信息: http : //docs.python.org/2/tutorial/datastructures.html#list-comprehensions
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