chap2(1).rar

""" knowledge:list的使用 author:zhy update:20230314 """ # 1. 创建list # 1.1 两种创建方式 # 空list # list1 = [] # list2 = list() # 注意不要采用赋值方式给空list赋值 # list1[0] = 'a' # 错误 # 包含各种元素的list # list1 = ["hello", "python", "world"] # list2 = ["china", 100, False] # 2. list的大小 # m = len(list1) # print(m) # 3. 访问列表元素 # list1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] # print(list1[0]) # print(list1[9]) # print(list1[-1]) # print(list1[-2]) # print(list1[0:3]) # print(list1[:3]) # print(list1[5:10]) # print(list1[5:]) # print(list1[:]) # print(list1[-5:-1]) # print(list1[-5:]) # 4. 添加元素append # list1 = ["a", "b", "c"] # list1.append("end1") # list1.append("end2") # list1.insert(0, "start") # list2 = ["e", "f"] # list1.extend(list2) # 5. 删除元素 # list1 = ["a", "b", "c"] # list1.pop(1) # list1.pop() # list1.remove('a') # del list1[1] # 6. 清空元素 # list1.clear() # 7. 排序 list1 = [21, 15, 3, 41, 25] list2 = ["hello", "python", "world"] # 7.1 sort方法--直接对原list排序 # list1.sort() # list1.sort(reverse=True) # list2.sort(key=len) # 7.2 sorted方法--排序影响新的list，对原list没影响 # list2 = sorted(list1) # 7.3 reverse方法 # list1.reverse() # 8. 列表推导式-由现有列表产生新的列表 list1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] list2 = [x*2 for x in list1] list2 = [x*x for x in list1] list2 = [x for x in list1 if x % 2 == 0] list1 = [1, 2, 3] list2 = [11, 12, 13] list3 = [x + y for x in list1 for y in list2] print(list3) # print(list1) print(list2)