• 其他
  • 变量值交换
  • 展开变量
  • 条件判断
  • 字符串嵌变量
  • 数组循环
  • 数组查重
  • 数组排序
  • 数组内包
  • 错误处理 和 with

其他

变量值交换

x, y = 100, 200
x, y = y, x

展开变量

mylist = [100, 200]
newlist = [*mylist, 300, 400]
mydic = { "name": "test", "time": 2016 }
newdic = { **mydic, "price": 1000 }

条件判断

myprofile = { "name": "koma", "age": 25 }
if "age" in myprofile and myprofile["age"] <= 30:
    print("年轻有为")
# 变量 = 真值 if 条件 else 假值
score = 15
result = "超级" if score >= 20 else "普通"
print(result)

字符串嵌变量

dbname = "PostgreSql"
print("学习" + dbname) # 字符串连接
print(f"学习{dbname}") # f文字串
print("学习{0}".format(dbname)) # format函数
print("学习%s" % dbname) # %

数组循环

mylist = [1, 2, 3, 5, 8, 13]
for index in range(len(mylist)):
    print(mylist[index], end=' ')
for val in mylist:
    print(val, end=' ')
for index, val in enumerate(mylist):
    print(index, val)
# 倒序
for val in reversed(mylist):
    print(val, end=' ')
for index, val in enumerate(reversed(mylist)):
    print(index, val)
# 字典
mydic = { "name": "test", "time": 2016, "price": 1000 }
for key in mydic:
    print('key:', key, 'value:', mydic[key], end=', ')
for key, val in mydic.items():
    print('key:', key, 'value:', val, end=', ')

数组查重

mytest1 = [1, 2, 3, 3, 5]
mytest2 = ['a', 'b', 'c', 'c', 'd']
print(list(set(mytest1)))
print(list(set(mytest2)))

数组排序

mylist = [21, 1, 2, 3, 5, 8, 13]
print(sorted(mylist, reverse=True)) # 降序排列
mylist = [[2, 20], [1, 10], [3, 30]]
print(sorted(mylist, key=lambda item: item[1])) # 指定排序 key
mylist = [
    { "name": "curry", "age": 32 },
    { "name": "lebron", "age": 36 },
    { "name": "harden", "age": 31 },
]
print(sorted(mylist, key=lambda item: item["age"])) # 字典排序

数组内包

mytest = []
for i in range(5):
    mytest.append(i*i)
mytest = [i*i for i in range(10)] # 内包

错误处理 和 with

myfile = open("sample/test.json", "r")
try:
    content = myfile.read()
    raise Exception('test')
except:
    pass
finally:
    myfile.close()
# with 句柄自动关闭
with open("sample/test.json", "r") as myfile:
    content = myfile.read()