Python matrix

Author: alisx

taiyangxue/README.md

@@ -14,6 +14,7 @@
 - [showdata](https://github.com/JustDoPython/python-examples/tree/master/taiyangxue/showdata) : Flask + echarts 轻松搞定 nginx 日志可视化
 - [dice](https://github.com/JustDoPython/python-examples/tree/master/taiyangxue/dice) : 做硬核老爸，我用 Python
 - [python39](https://github.com/JustDoPython/python-examples/tree/master/taiyangxue/python39) : 你在享受十一长假时，Python 已悄悄地变了
+- [matrix](https://github.com/JustDoPython/python-examples/tree/master/taiyangxue/matrix) : Python 世界的黑客帝国
 
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taiyangxue/matrix/chain.py

@@ -0,0 +1,11 @@
+# 命令行下执行
+# 思考下下面表达式的值
+
+(False == False) in [False] # 合乎常理
+False == (False in [False]) # 也没问题
+False == False in [False] # 现在感觉如何?
+True is False == False
+False is False is False
+1 > 0 < 1
+(1 > 0) < 1
+1 > (0 < 1)

taiyangxue/matrix/eatjs.py

@@ -0,0 +1,7 @@
+some_dict = {}
+some_dict[5.5] = "Ruby"
+some_dict[5.0] = "JavaScript"
+some_dict[5] = "Python"
+
+print(some_dict[5.5])  # Ruby
+print(some_dict[5.0])  # Python  Javascript 去哪了

taiyangxue/matrix/is.py

@@ -0,0 +1,16 @@
+# 命令行下执行
+a = 256
+b = 256
+a is b  # 值是什么
+
+a = 257
+b = 257
+a is b  # 值是什么
+
+a = []
+b = []
+a is b  # 值是什么
+
+a = tuple()
+b = tuple()
+a is b  # 值是什么

taiyangxue/matrix/sting.py

@@ -0,0 +1,13 @@
+# 命令行下执行
+
+a = "some_string"
+id(a)
+id("some" + "_" + "string") # 不同方式创建的字符串实质是一样的.
+
+a = "wtf"
+b = "wtf"
+a is b  # 想想结果是什么
+
+a = "wtf!"
+b = "wtf!"
+a is b  # 结果又会是什么

taiyangxue/matrix/walrus.py

@@ -0,0 +1,22 @@
+# 海象操作符
+
+a = [1,2,3,4,5]
+if n := len(n) > 4:
+    print(n)
+
+# 命令行中执行
+a = "wtf_walrus"
+a := "wtf_walrus"  # 报错！
+(a := "wtf_walrus") # 奇迹发生，竟然通过了！
+
+a = 6, 9  # 元组赋值
+
+(a := 6, 9)  # 海象赋值，表达式结果正常
+# 现在 a 的值是多少？
+
+a, b = 6, 9 # 解包赋值
+(a, b = 16, 19) # Oh no！
+
+(a, b := 16, 19) # 这里竟然打印出三员元组！
+
+# 现在的 a 是多少？