python中怎么从列表怎么取出数字
python\u4e2d\u5982\u4f55\u63d0\u53d6\u4e00\u7ec4\u6570\u636e\u4e2d\u7684\u7b2c\u4e00\u5217\u6570\u636e\u6982\u8ff0\u76f4\u63a5\u63d0\u53d6\u4f1a\u62a5\u9519\uff0c\u628aarray\u6570\u7ec4\u8f6c\u6362\u6210list\uff0c\u5373\u53ef\u63d0\u53d6\uff0c\u4f7f\u7528numpy\u8f6c\u6362
\u6b65\u9aa4\u8be6\u89e31\u3001\u76f4\u63a5\u63d0\u53d6\u5c1d\u8bd5\uff1a
group=[[1,2],[2,3],[3,4]]
#\u63d0\u53d6\u7b2c\u4e00\u5217\u5143\u7d20
print(group[:,1])
#Out:TypeError: list indices must be integers or slices, not tuple
2\u3001\u4f7f\u7528numpy\u8f6c\u6362\uff1a
import numpy as np
group=[[1,2],[2,3],[3,4]]
#numpy\u8f6c\u5316
ar=np.array(group)
print(ar[:,1])
#Out:[2 3 4]
\u62d3\u5c55\u5185\u5bb9numpy\u8be6\u89e3
Numpy\u5bf9\u8c61\u662f\u6570\u7ec4\uff0c\u79f0\u4e3andarray \u7ef4\u5ea6(dimensions)\u79f0\u4f5c\u8f74(axes),\u8f74\u7684\u4e2a\u6570\u53eb\u505a\u79e9(rank)\u3002\u6ce8\uff1a\u6709\u51e0\u7ea7\u4e2d\u62ec\u53f7\u5c31\u6709\u51e0\u4e2a\u7ef4\u5ea6
\u4e00\u3001ndarray.attrs:
ndarray.ndim \u79e9
ndarray.shape \u4f8b\u5982\u4e00\u4e2a2\u63923\u5217\u7684\u77e9\u9635\uff0c\u5b83\u7684shape\u5c5e\u6027\u662f(2,3)
ndarray.size \u6570\u7ec4\u5143\u7d20\u7684\u603b\u4e2a\u6570
ndarray.dtype \u5143\u7d20\u7c7b\u578b\uff0cNumPy\u63d0\u4f9b\u81ea\u5df1\u7684\u6570\u636e\u7c7b\u578b
ndarray.itemsize \u6570\u7ec4\u4e2d\u6bcf\u4e2a\u5143\u7d20\u7684\u5b57\u8282\u5927\u5c0f
\u4e8c\u3001\u6570\u7ec4\u521b\u5efa\u51fd\u6570\uff1a
array
asarray\u5c06\u8f93\u5165\u8f6c\u6362\u6210ndarray
arange
ones
zeros
empty \u53ea\u5206\u914d\u5185\u5b58\u7a7a\u95f4\u4e0d\u586b\u5145\u4efb\u4f55\u503c
eye \u521b\u5efaN*N\u5355\u4f4d\u77e9\u9635(\u5bf9\u89d2\u7ebf\u4e3a1)
\u4e09\u3001\u6570\u7ec4\u548c\u6807\u91cf\u4e4b\u95f4\u7684\u8fd0\u7b97
numpy\u6570\u7ec4\u7684\u4e00\u4e2a\u7279\u70b9\uff0c\u4e0d\u7528\u7f16\u5199\u5faa\u73af\u5c31\u53ef\u5bf9\u6570\u636e\u6267\u884c\u6279\u91cf\u8fd0\u7b97\uff0c\u8fd9\u901a\u5e38\u79f0\u4f5c\u77e2\u91cf\u5316(vectorization)\u3002
\u56db\u3001\u57fa\u672c\u7684\u7d22\u5f15\u548c\u5207\u7247
numpy\u6570\u7ec4\u7684\u7d22\u5f15\u662f\u4e00\u4e2a\u5185\u5bb9\u4e30\u5bcc\u7684\u4e3b\u9898\uff0c\u56e0\u4e3a\u9009\u53d6\u6570\u636e\u5b50\u96c6\u6216\u5355\u4e2a\u5143\u7d20\u7684\u65b9\u5f0f\u6709\u5f88\u591a\u3002\u8fd9\u91cc\u6211\u4ec5\u8be6\u7ec6\u4ecb\u7ecd\u5e38\u7528\u7684\u65b9\u6cd5\uff0c\u5bf9\u4e8e\u9ad8\u7ea7\u529f\u80fd\u7684\u65b9\u5f0f\u6211\u5217\u4e3e\u540d\u79f0\uff0c\u8bfb\u8005\u53ef\u4ee5\u7b49\u5230\u8981\u7528\u7684\u65f6\u5019\u81ea\u884c\u67e5\u9605\u8d44\u6599\u3002
以取出最大值和最小值为例：
1、如需求列表中的最大值，用python自带的函数max() 即可。代码示例如下：
numbers = [1,2,3,4,5,6,7,8,9]
max(numbers)
2、求最大值也可通过定义函数，再调用函数求得。示例代码如下：
def findmax(L):
if L == []:
return(None)
else:
Max = L[0]
for i in L:
if i > Max:
Max = i
return(Max)
numbers = [6,2,9,4,5,1,7,8,3]
findmax(numbers)
3、如需求列表中的最小值，用python自带的函数min() 即可。代码示例如下：
numbers = [1,2,3,4,5,6,7,8,9]
min(numbers)
4、求最小值也可通过定义函数，再调用函数求得。示例代码如下：
def findmin(L):
if L == []:
return(None)
else:
Min = L[0]
for i in L:
if i < Min:
Min = i
return(Min)
numbers = [6,2,9,4,5,1,7,8,3]
findmin(numbers)
'''
可以同时筛选Python支持的4种数字类型：
方法：取出列表中每个项，判断其是否是Python支持的数字类型；如果是，则取出来放进新建列表中。
'''
# -*- coding: utf-8 -*-
#原始列表
tempList = ['11', 1, '22' ,2 ,'3' ,'4' , 'lolo' ,'lala', 1.25]
#存放数字列表
numList = []
#筛选Python支持的4种数字类型
#lambda函数循环列表，type函数判断列表各项类型
numList = filter(lambda x: type(x)==int or type(x)==long
or type(x)==float or type(x)==complex, tempList)
筛选结果：
1
2
1.25
def filterNum(alist):
container = []
for item in alist:
if isinstance(item,int) or isinstance(item,float)://筛选浮点数和整数
container.append(item)//放入container
return container
if __name__ == "__main__":
alist = [1,"dfd","aaa",2.3,34]
numcontainer = filterNum(alist);
提取列表里的整数和浮点数
可以参考下面的资料，过for 然后从A的数组取出到a，然后取出
import re
a = [列表]
c = []
for x in a:
c.append(re.findall(r'\d+',x))
or :
>>> a = ['1',1,'2',2,'3','4','abc','4a5c']
>>> filter(lambda x: type(x)==int, a)
[1, 2]
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