1、python的數據類型java
1.python的基本數據類型包括數值數據類型和字符串數據類型;基本數據類型的特色是不容許改變,若是改變基本數據類型的值,會致使內存的從新分配。python
intc++ |
整形git |
二進制 a = 0b1010app 八進制 a = 0o37dom 十進制 a = 25函數 十六進制 a = 0x34aui |
floatspa |
浮點型code |
f1 = 0.12,f2 = 1.343e-3 |
bool |
布爾型 |
flag = True |
complex |
複數類型 |
a = complex(2,3) |
2.數值的相互轉換函數
轉十六進制 |
hex() |
轉八進制 |
oct() |
轉二進制 |
bin() |
轉整形 |
int() |
3.變量的三個屬性
標識 |
變量的內存地址,能夠用id()查看 |
類型 |
變量的類型,能夠用type()查看 |
值 |
存儲的值 |
4.判斷某個變量是不是某種類型實例
print(isinstance(3, float)) #False
5.複數類型的使用
a = complex(2,2) b = complex("3+2j") print(a) print(b) print(a+b) print(a-b) print(a*b) print(a/b)(2+2j)
6.python的字符串類型不像Java能夠與數值類型相加,如「str」+1會報錯,但python支持字符串與數值相乘,表示將字符串重複多少次。
#報錯 #print("str"+1)
#重複字符串 print("The life is short,i love python\n" * 3) #The life is short,i love python #The life is short,i love python #The life is short,i love python
#轉爲大寫 print("lower".upper()) #LOWER
#轉爲小寫 print("UPPER".lower()) #upper
#去除前導和尾部空白 print(" hello python ".strip()) #hello python
#也能夠指定去除的字符 print("##hello python##!".strip("#!")) #hello python
#求長度 print(len("hello")) #5
#拆分字符串 print("orange banana apple".split(" ")) #['orange', 'banana', 'apple']
#用指定字符串鏈接一個列表 print(" ".join(["orange","apple","banana","peach"])) #orange apple banana peach
#判斷字符串是否以某個子串開始 print("good good study".startswith("go")) #True
#判斷字符串是否以某個子串開始 print("day day up".endswith("up")) #True
#統計子串出現次數 print("Python is a nascent programming language.".count("p")) #1
#查找子串出現的下標 print("Sometimes your whole life boils down to one insane move.".find("wh")) #15
#判斷是不是數字 print("moive".isdigit()) #False
#判斷是不是字母 print("money".isalpha()) #True
#判斷是不是空格 print("i declared".isspace()) #False
7.Python的字符串最強大之處是切片操做
str = "Attitude determines altitude." #取出Attitude(外國人的習慣是左閉右開,即包括左下標,不包括右下標)
print(str[0:9]) #Attitude
print(str[0:20:3]) #Aiddeis (每3個取一個)
print(str[-5:-1]) #tude
8.Python的字符串能夠用單引號,雙引號,三引號表示,但字符串跨行時只能用三引號或反斜槓
str = '''Be a laborious bee '''
print(str) str1 = "Be \ a \ hard-working \ man" print(str1) #Be a hard-working man
9.實現字符串反轉
#切片 str[開始位置:結束位置:步數] 將步數設爲-1 def strReverse1(str): return str[::-1]
#將字符串轉爲列表,反轉後再鏈接爲字符串 def strReverse2(str): newList = list(str) newList.reverse() return "".join(newList)
print(strReverse1("python")) print(strReverse2("python"))
2、輸入輸出
一、輸入函數input()
#輸入一個字符串 myStr = input("請輸入一個字符串:") print(myStr) #以逗號分割輸入多個數 a,b,c = eval(input("請輸入3個數:")) print(a,b,c)
2.輸出函數 print()
#以逗號分割輸出多個變量,輸出後顯示的分隔符是空格,結尾會輸出一個換行符 print("i","am","studying","python") #i am studying python #指定分隔符和結尾符 print("i","am","studying","python",sep="#",end=" ") print() #相似c語言的輸出 name = "jackson" age = 22 salary = 5000.0 print("name:%s,age:%d,salary:%.3f" % (name,age,salary)) #python特有的輸出形式 print("I like eating {} and {}".format("banana", "pear")) #按位置填充 print("His name is {name} and he is a {sex}".format(sex='male',name='judy')) #按具體名字填充 print("{1} can arm our {0}".format("brain","knowledge")) #按編號填充 print("The happiness rate of chinese citizen is up to {:.3f}".format(0.45)) #設置浮點數輸出格式爲小數點後三位 print("The population of china is {:,d} million".format(1300)) #千分位用逗號表示
3、集合數據類型
Python的集合數據類型包括列表,元組,字典,集合
列表 |
list(內部元素能夠從新賦值,列表和列表能夠相加,列表和數字能夠相乘) |
arr = ["jack"] |
元組 |
tuple(內部元素不能從新賦值,元組能夠和元組相加,元組能夠和數字相乘) |
myTuple = ("nacy","rose") |
字典 |
dict(無序,可從新賦值,鍵惟一,值不惟一,鍵爲不可變元素) |
myMap = {"name":"zhangshan","age":12} |
集合 |
set(無序,惟一,可進行集合間的交併差補) |
mySet1= set(["judy","tom","martin"]) mySet2 = set("lily") |
1.列表
#四種遍歷方式
fruits = ["orange","banana","pear","peach"]
for item in fruits: print(item,end=" ") print() for item in iter(fruits): print(item,end=" ") print() for i,item in enumerate(fruits): print(i,"===>",item,end=" ") print() for item in range(len(fruits)): print(fruits[item],end=" ") print() #重複列表四次 print(fruits*4) #['orange', 'banana', 'pear', 'peach', 'orange', 'banana', 'pear', 'peach', 'orange', 'banana', 'pear', 'peach', 'orange', 'banana', 'pear', 'peach'] #列表鏈接 print(fruits+["pineapple","apple"]) #刪除指定下標的元素,不提供參數則刪除表尾元素 print(fruits.pop(2)) #['orange', 'banana', 'pear', 'peach', 'pineapple', 'apple'] #追加元素 append追加和extend追加有區別 #append追加的是列表 #extend追加的是元素 fruits.append(["Coconut"]) print(fruits) #['orange', 'banana', 'peach', ['Coconut']] fruits.pop() fruits.extend(["Coconut"]) print(fruits) #['orange', 'banana', 'peach', 'Coconut'] #列表反轉 fruits.reverse() print(fruits) #['Coconut', 'peach', 'banana', 'orange'] #指定位置插入 fruits.insert(2, "nothing") print(fruits) #['Coconut', 'peach', 'nothing', 'banana', 'orange'] #刪除列表切片 del fruits[1:3] print(fruits) #['Coconut', 'banana', 'orange']
2.元組
myTuple1 = ("bird","plane","vehicle","subway") #不能對單個元素從新賦值(報錯) #myTuple1[0] = "parrot" #但能夠對整個元組賦值 myTuple1 = ("python","c++","java") print(myTuple1) #('python', 'c++', 'java') #建立空元組 emptyTuple = () print(emptyTuple) #() #注意建立一個元素的元組要在結尾加逗號 oneTuple = (1) print(oneTuple) #1 不加逗號編譯器會認爲括號是進行算數運算,而不是建立元組 oneTuple = (1,) print(oneTuple) #(1,) #元組的取值 print(myTuple1[0]) #python print(myTuple1[:]) #('python', 'c++', 'java') print(myTuple1[:1]) #('python',) print(myTuple1[len(myTuple1)-1:]) #('java',) #元組的重複 print(myTuple1 *4) #('python', 'c++', 'java', 'python', 'c++', 'java', 'python', 'c++', 'java', 'python', 'c++', 'java') #元組相加 print(myTuple1 + ("one","two","three")) #('python', 'c++', 'java', 'one', 'two', 'three')
3.字典
myDict = {"one":1,"two":343.33,"three":True} #字典的取值 print(myDict["one"]) #1 #判斷鍵是否存在 print("three" in myDict) #True #更新值 myDict["one"] = 100 print(myDict) #{'one': 100, 'two': 343.33, 'three': True} #清空字典 myDict.clear() print(myDict) #{}
4.集合
#以字符串建立set,自動去除重複元素 mySet = set("hello") print(mySet) #{'o', 'l', 'e', 'h'} #以list建立set mySet1 = set(["a","m","e","o"]) print(mySet1) #{'o', 'a', 'm', 'e'} #以map建立set,值爲map的鍵 mySet2 = set({"name":1,"age":2}) print(mySet2) #{'name', 'age'} #交集 print(mySet & mySet1) #{'e', 'o'} #並集 print(mySet | mySet1) #{'l', 'a', 'e', 'h', 'm', 'o'} #差集 print(mySet - mySet1) #{'l', 'h'} #對稱差分運算 print(mySet ^ mySet1) #{'l', 'a', 'h', 'm'}
4、強大的列表解析功能
import random #列表解析 #生成10個隨機數,返回一個新列表 list1 = [random.randint(0,100) for i in range(0,10)] for item in list1: print(item,end=" ") #74 38 75 45 96 1 38 93 58 80 print() #求1到20的平方組成的列表 list2 = [i*i for i in range(1,21)] for num in list2: print(num,end=" ") #1 4 9 16 25 36 49 64 81 100 121 144 169 196 225 256 289 324 361 400 #選出list2中的偶數 list3 = [i for i in list2 if i % 2 == 0] for num in list3: print(num) #4 16 36 64 100 144 196 256 324 400 #按行遍歷矩陣 list4 = [[1,2,3,4],[5,6,7,8],[2,3,4,5],[6,7,8,9]] list5 = [[1,4,5,6],[2,1,3,4],[3,4,2,1],[7,8,2,1]] print([row for row in list4]) #[[1, 2, 3, 4], [5, 6, 7, 8], [2, 3, 4, 5], [6, 7, 8, 9]] #按列遍歷矩陣 print([list4[row][1] for row in range(len(list4))]) #[2, 6, 3, 7] #遍歷對角線 print([list4[i][i] for i in range(len(list4))]) # [1, 6, 4, 9] #逐個遍歷 print([list4[row][col] for row in range(len(list4)) for col in range(len(list4[row]))]) #[1, 2, 3, 4, 5, 6, 7, 8, 2, 3, 4, 5, 6, 7, 8, 9] #矩陣相加 print([list4[row][col] + list5[row][col] for row in range(list4.__len__()) for col in range(list4[row].__len__())]) #[2, 6, 8, 10, 7, 7, 10, 12, 5, 7, 6, 6, 13, 15, 10, 10] #轉置矩陣 print([row for row in zip(*list4)]) #[(1, 5, 2, 6), (2, 6, 3, 7), (3, 7, 4, 8), (4, 8, 5, 9)] #求最大長度對應的字符 students = ["jack","shirely","kangkang","mary"] maxLen = max([len(item) for item in students]) print(maxLen) maxStr = [temp for temp in students if len(temp) == maxLen] print(maxStr) #['kangkang']
5、內置函數
#幾個內置的高階函數 map,filter,reduce,sorted #map用於將一函數規則應用於一可迭代集合的全部元素 #reduce用於將一函數規則反覆做用於一可迭代集合的元素,傳入的函數參數必須爲兩個 #filter將一可迭代集合中適用於函數規則的元素挑選出來 #sorted用於對可迭代集合進行排序 #map的一個栗子(將字符串轉爲對應數字)
#匿名函數求對應字符的數字表示如'0'對應數字0,'1'對應1
f = lambda ch:{"0":0,"1":1,"2":2,"3":3,"4":4,"5":5,"6":6,"7":7,"8":8,"9":9}[ch]
#上面函數的功能與這個同樣 f1 = lambda ch:int(ch)
print(list(map(f,"322"))) #[3, 2, 2] #reduce的一個栗子(將字符串轉換爲對應的十進制數) def str2Decimal(x,y): return x*10 + y print(reduce(str2Decimal,map(f,"232"))) #232 #filter的一個栗子(使用埃氏篩選法篩選素數) seq = range(2,51) for i in seq: f = lambda x : x == i or x % i seq = list(filter(f,seq)) print(list(seq)) #[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47] #sorted的一個栗子 rules = lambda x:x.lower() reles2 = lambda x:x["age"] students = ["jack","Nacy","Kangkang","asia"] aMap = [{"name":"kangknag","age":25},{"name":"ag","age":13},{"name":"wnag","age":23}] newlist = sorted(students, key=rules, reverse=False) print(sorted(aMap,key=reles2)) #[{'name': 'ag', 'age': 13}, {'name': 'wnag', 'age': 23}, {'name': 'kangknag', 'age': 25}] print(newlist) #['asia', 'jack', 'Kangkang', 'Nacy']
先寫到這吧,有點累。。。