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Python常用命令之集合

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  • 判断数据项是否存在list
    •         
thislist = ["apple", "banana", "cherry"]
if "apple" in thislist:
  print("Yes, ‘apple‘ is in the fruits list")
    • 遍历list 
      thislist = ["apple", "banana", "cherry"]
for x in thislist:
print(x)

    获取list长度

            thislist = ["apple", "banana", "cherry"]
print(len(thislist))

    追加元素

            thislist = ["apple", "banana", "cherry"]

thislist.append("orange")

print(thislist)

    添加固定位置

            thislist = ["apple", "banana", "cherry"]
thislist.insert(1, "orange")
print(thislist)

    删除某元素【只删除一个】

            thislist = ["apple", "banana", "cherry"]
thislist.remove("banana")
print(thislist)

    移除最后一个元素

            thislist = ["apple", "banana", "cherry"]
thislist.pop()
print(thislist)

    清空List

            thislist = ["apple", "banana", "cherry"]
thislist.clear()
print(thislist)

    修改元组值

            
x = ("apple", "banana", "cherry")
y = list(x)
y[1] = "kiwi"
x = tuple(y)

print(x)

    声明元组

            thistuple = ("apple",)
print(type(thistuple))

#NOT a tuple type is str
thistuple = ("apple")

    合并元组Tuple 【不会去重】

            tuple1 = ("a", "b" , "c")
tuple2 = (1, 2, 3)

tuple3 = tuple1 + tuple2
print(tuple3)

    构造元组【2个括号】

            thistuple = tuple(("apple", "banana", "cherry")) # note the double round-brackets
print(thistuple)

    声明Set

            thisset = {"apple", "banana", "cherry"}
print(thisset)

    Set添加元素

            thisset = {"apple", "banana", "cherry"}

thisset.add("orange")

print(thisset)

    批量添加

            thisset = {"apple", "banana", "cherry"}

thisset.update(["orange", "mango", "grapes"])

print(thisset)

    Set 删除元素

            
thisset = {"apple", "banana", "cherry"}
//不存在  抛异常
thisset.remove("banana")
//不存在  不抛异常
thisset.discard("banana")

// 不知道删的内容
x = thisset.pop()

print(thisset)

    合并set 内容

            set1 = {"a", "b" , "c"}
set2 = {1, 2, 3}

set3 = set1.union(set2)
print(set3)

    合并set 内容(不需要新变量）

            set1 = {"a", "b" , "c"}
set2 = {1, 2, 3}

set1.update(set2)
print(set1)

    声明set

            thisset = set(("apple", "banana", "cherry")) # note the double round-brackets
print(thisset)

    Dictionary

    创建字典

            thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}

    访问字段元素

            # 如果没有值，异常
x = thisdict["mod1el"]
print(x)

# 如果没有值，返回None
x = thisdict.get("mo1del")
print(x)

    输出字典的值

            for x in thisdict.values():
  print(x)

    输出字典的k,v

            for x, y in thisdict.items():
  print(x, y)

    复制 Dictionary

            thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
mydict = thisdict.copy()
print(mydict)

    原文：https://blog.51cto.com/dba10g/2488431

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