2025-09-10:仓库迁移

1.数据结构与算法/17.字典子集.py

@@ -0,0 +1,19 @@
+# 假如我们有一个字典,需要提取子集:
+price = {
+    "ACME": 45.23,
+    "AAPL": 612.78,
+    "IBM": 205.55,
+    "HPQ": 37.2,
+    "FB": 10.75
+}
+
+# 直接用字典推导式
+p1 = {key :value for key, value in price.items() if value > 200}
+
+# 提取key也是
+keys = {"AAPL", "IBM", "HPQ", "MSFT"}
+p2 = {key : value for key, value in price.items() if key in keys}
+
+# 字典推导式是最快的方法,比下面两个办法都快:
+dict((key, value) for key, value in price if value > 100)   # 快两倍
+{key:price[key] for key in price.keys() if key in price.keys() & keys} # 快1.6倍