python数据类型之list

1、append:增加元素到列表尾部

L.append(object) -> None -- append object to end

2、clear:清空列表中所有元素

3、count:返回列表中指定值的数量

L.count(value) -> integer -- return number of occurrences of value

4、extend:用列表扩展列表的元素

#L.extend(iterable) -> None -- extend list by appending elements from the iterable
l1 = [1,2,3]
l2 = [3,4,5]
l1.extend(l2)
print(l1)

5、index:返回指定元素的索引位置

#L.index(value, [start, [stop]]) -> integer -- return first index of value
lx = ['today','is','a','good','day']
print(lx.index('is'))
结果：1

6、insert:在指定索引位置插入

#L.insert(index, object) -- insert object before index
lx = ['today','is','a','good','day']
lx.insert(2,'not')
print(lx)
结果：['today', 'is', 'not', 'a', 'good', 'day']

7、pop：删除列表指定位置的元素，默认为最后一个元素

#L.pop([index]) -> item -- remove and return item at index (default last)
lx = ['today','is','a','good','day']
lx.pop(2)
print(lx)
结果：['today', 'is', 'good', 'day']

8、remove:删除列表中指定的元素

#L.remove(value) -> None -- remove first occurrence of value
lx = ['today','is','a','good','day']
lx.remove('a')
print(lx)
结果：['today', 'is', 'good', 'day']

9、reverse:将列表中所有元素反转

#L.reverse() -- reverse *IN PLACE*
lx = ['today','is','a','good','day']
lx.reverse()
print(lx)
结果：['day', 'good', 'a', 'is', 'today']

10、sort：排序

#原址排序
x= [3,2,4,6,5,7,9,8]
x.sort()
print(x)
结果：[2, 3, 4, 5, 6, 7, 8, 9]

#需要一个排序好的副本，通过切片方法将x赋值给y
x= [3,2,4,6,5,7,9,8]
y = x[:]
y.sort()
print(x)
print(y)
结果：
[3, 2, 4, 6, 5, 7, 9, 8]
[2, 3, 4, 5, 6, 7, 8, 9]

#再一种通过sorted
x= [3,2,4,6,5,7,9,8]
y = sorted(x)
print(x)
print(y)
结果：
[3, 2, 4, 6, 5, 7, 9, 8]
[2, 3, 4, 5, 6, 7, 8, 9]

 11、filter:使用一个自定义的涵数过滤一个序列，把函数的每一项传到自定义的函数里处理，最终一次性返回过滤的结果

def func(x):
    if x >33:
        return True

li = [11,22,33,44,55]
new_list = filter(func,li)
print(list(new_list))
结果：[44,55]

12、zip:接受任意多个序列，返回一个元组

x = [1,2,3]
y = [4,5,6]
z = [7,8,9]
zipped = zip(x,y,z)
yy = list(zipped)
xyz =zip(*yy)   #zip的反函数
print(yy)
print(list(xyz))
结果：
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]
[(1, 2, 3), (4, 5, 6), (7, 8, 9)]

13、tell：查看当前指针位置

　　seek：定位当前指针位置

'''test.llog
孔kongzhagen
'''

f = open('test.log','r+',encoding='utf-8')
f.read(2)
print(f.tell()) #查看当前指针位置

f.seek(6)
f.read(2)
print(f.tell())
结果：4,8

14、truncate: truncate(n):  从文件的首行首字符开始截断，截断文件为n个字符；无n表示从当前位置起截断；截断之后n后面的所有字符被删除。其中win下的换行代表2个字符大小。

'''
# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line
'''
f = open("test.log","r+")
print('Name of file %s'%f.name)
line = f.readline()
print('Read line:%s'%line)
f.truncate(f.tell()) #文件保留了第一行，其余被截断
line = f.readline()
print('Read line:%s'%line)
f.close()
结果:
Name of file test.log
Read line:# Assuming file has following 5 lines

Read line:# This is 1st line

 其它

numList = [1,2,2,23,4,5]
strList = ['a','b','c','d','e']
numList.append(6)  # numList列表增加一个值
print numList
print numList.count(2)  # 列表中2出现的次数
numList.extend(strList)  # strList的内容增加到numList后面
print numList
print numList.index(23)  # numList中23的索引位置
numList.insert(3,45)   # 在numList的3索引位置添加45
print numList
print numList.pop()  # 获取并删除numList最后一个值
numList.remove(4)  # 从numList中删除4
print numList
numList.reverse()  # 获取numList的反向列表
print numList