一.列表
由于pyhon的變量沒有數據類型,所以python是沒有數組的(因為數組只能存放一種類型,要么全部存放整型,要么全部存放浮點型),只有列表list,所以整數,浮點數,字符串,對象都可以塞進去.
創建一個普通列表:
>>> member = [1,2,3,4]
>>> member
[1, 2, 3, 4]
創建一個混合列表:
>>> member = [1,'哈哈',2,3]
>>> member
[1, '哈哈', 2, 3]
創建一個空列表:
>>> member = []
>>> member
[]
向列表添加元素:?
>>> member = []
>>> member
[]
>>> member.append('小紅')
>>> member
['小紅']
>>> member.append('小藍')
>>> member
['小紅', '小藍']
len會輸出數組長度:
>>> len(member)
2
insert向數組中插入元素:
>>> member
['小紅', '小藍']
>>> member.insert(1,'小綠')
>>> member
['小紅', '小綠', '小藍']
0表示的是第一個元素:
>>> member
['小紅', '小綠', '小藍']
>>> member[0]
'小紅'
>>> member[1]
'小綠'
>>> member[2]
'小藍'
從數組中獲取元素:
>>> member
['小紅', '小綠', '小藍']
>>> temp = member[2]
>>> temp
'小藍'
remove()函數從數組中刪除某個元素:
>>> member
['小紅', '小綠', '小藍']
>>> member.remove('小綠')
>>> member
['小紅', '小藍']
del()函數也表示從列表中刪除某個元素:
>>> member
['小紅', '小藍']
>>> del member[0]
>>> member
['小藍']
pop()函數從列表中取出最后一個元素:
>>> member
['小藍', '小紅', '小綠']
>>> member.pop()
'小綠'
利用索引值,每次我們可以從列表獲取一個元素,但是我們總是貪心的,如果一次性需要獲取多個元素,有沒有辦法實現呢?利用列表分片,我們可以簡單的實現這個要求。
member[0:2]表示從第0個元素開始獲取,共獲取2個,member[0],member[1].
>>> member
['小藍', '小紅', '小綠']
>>> member[0:2]
['小藍', '小紅']
>>> member
['小藍', '小紅', '小綠']
>>> member[0:3]
['小藍', '小紅', '小綠']
列表的拷貝:
>>> member
['小藍', '小紅', '小綠']
>>> temp = member[:]
>>> temp
['小藍', '小紅', '小綠']
>>> tem = member
>>> tem
['小藍', '小紅', '小綠']
列表的一些常用操作符:
比較操作符:
>>> list1 = [123]
>>> list2 = [456]
>>> list1 < list2
True
邏輯操作符:
>>> (list1<list2) and (list1 != list2)
True
>>> (list1>list2) and (list1 != list2)
False
連接操作符:
>>> list3 = list1+list2
>>> list3
[123, 456]
重復操作符:
>>> list3 *= 3
>>> list3
[123, 456, 123, 456, 123, 456]
成員關系操作符:
>>> list3
[123, 456, 123, 456, 123, 456]
>>> 123 in list3
True
>>> 234 in list3
False
>>> 123 not in list3
False
count()函數可計算列表中相同元素個數:
>>> member
['小藍', '小紅', '小綠']
>>> member.count('小紅')
1
index()函數可索引列表元素位置:
>>> member
['小藍', '小紅', '小綠']
>>> member.index('小紅')
1
>>> member.index('小綠')
2
>>> member.index('小藍')
0
sort()將列表中元素從小到大排序:
>>> temp = [1,5,3,6]
>>> temp
[1, 5, 3, 6]
>>> temp.sort()
>>> temp
[1, 3, 5, 6]
二.元組
由于和列表是近親關系,所以元組和列表在實際使用上是非常相似的.
創鍵和訪問一個元組:
創建元組(括號可以沒有,但逗號一定要有)
>>> temp = 1,2,3,4,5
>>> temp
(1, 2, 3, 4, 5)
訪問元組前兩個元素:
>>> temp
(1, 2, 3, 4, 5)
>>> temp[:2]
(1, 2)
元組的拷貝:
>>> temp1 = temp
>>> temp1
(1, 2, 3, 4, 5)
注意,不能更改元組中的元素:
>>> temp1
(1, 2, 3, 4, 5)
>>> temp1[1] = 0
Traceback (most recent call last):File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
更新和刪除一個元組:只能利用類似字符串的切片的方式間接的更新刪除一個元素
>>> temp1
(1, 2, 3, 4, 5)
>>> temp1 = temp1[:2] + (2,) + temp1[3:]
>>> temp1
(1, 2, 2, 4, 5)
列表和元組的區別:元組不允許修改和刪除。
三.字符串
capitalize()把字符串的第一個字符改為大寫
>>> str = 'string'
>>> str.capitalize()
'String'
casefold() ?把整個字符串的所有字符改為小寫
>>> str1 = 'STRING'
>>> str1
'STRING'
>>> str1.casefold()
'string'
center(width)將字符串居中,并使用空格填充至長度width的新字符串
>>> str1
'STRING'
>>> str1.center(10)
' STRING '
字符串:格式化.
format()方法
{0},{1},{2}表示字段,通過位置參數“I”,“FishC”,“com”傳遞給format方法,然后對字符串進行格式化。
>>> "{0}love{1}.{2}".format("I","FishC","com")
'IloveFishC.com'
關鍵字參數{a},{b},{c}
>>> "{a}love{b}.{c}".format("I","FishC","com")
Traceback (most recent call last):File "<stdin>", line 1, in <module>
KeyError: 'a'
>>> "{a}love{b}.{c}".format(a = "I",b = "FishC",c= "com")
'IloveFishC.com'
字符串格式化符號
%c ?格式化字符及其ASCII碼
>>> '%c %c %c' %(97,98,99)
'a b c'
%s ?格式化字符串
>>> '%s' % 'I love you'
'I love you'
?%d ?格式化整數
>>> '%d + %d = %d' % (4,5,4+5)
'4 + 5 = 9'
%o ?格式化無符號八進制數
>>> '%o' % 10
'12'
%x ?格式化無符號十六進制數
>>> '%x' % 10
'a'
%X ?格式化無符號十六進制數(大寫)
>>> '%X' % 10
'A'
%f ?格式化定點數,可指定小數點后的精度,精進小數點后6位
>>> '%f' % 27.658
'27.658000'
格式化操作符輔助命令
m.n m是顯示的最小總寬度,n是小數點后的位數
>>> '%5.1f' % 27.678
' 27.7'
默認向右對齊10位
>>> '%10d' % 5
' 5'
- 用于左對齊
>>> '%-10d' % 5
'5 '
#在八進制數前面顯示 ‘0o’,在十六進制數前面顯示 ‘0x’ 或 ‘0X’
>>> '%#o' % 10
'0o12'
>>> '%#x' % 10
'0xa'
>>> '%#X' % 10
'0XA'
0 ? 顯示的數字前面填充 ‘0’ 取代空格
>>> '%010d' % 5
'0000000005'
>>> '%-010d' % 5
'5 '