examples

guozhen3 · guozhen3 · commit 3d760acfcf8a · 2019-12-11T13:28:05.000+08:00
diff --git a/README.md b/README.md
@@ -326,6 +326,35 @@ def bif_by(lst, Fn):
 
 records = [25,89,31,34] 
 bif_by(records, lambda x: x<80) # [[25, 31, 34], [89]]
+```
+18 联合统计多列表元素出现次数
+```python
+from collections import Counter
+a = ['apple', 'orange', 'computer', 'orange']
+b = ['computer', 'orange']
+
+ca = Counter(a)
+cb = Counter(b)
+#Counter对象间可以做数学运算
+ca + cb  # Counter({'orange': 3, 'computer': 2, 'apple': 1})
+
+
+进一步抽象，实现多个列表内元素的个数统计
+
+
+def sumc(*c):
+    if (len(c) < 1):
+        return
+    mapc = map(Counter, c)
+    s = Counter([])
+    for ic in mapc: # ic 是一个Counter对象
+        s += ic
+    return s
+
+
+#Counter({'orange': 3, 'computer': 3, 'apple': 1, 'abc': 1, 'face': 1})
+sumc(a, b, ['abc'], ['face', 'computer'])
+
 ```
 
 #### 四、字典
diff --git a/md/Counter的高级用法.md b/md/Counter的高级用法.md
@@ -0,0 +1,30 @@
+Counter对象间可以做数学运算
+
+```python
+from collections import Counter
+a = ['apple', 'orange', 'computer', 'orange']
+b = ['computer', 'orange']
+
+ca = Counter(a)
+cb = Counter(b)
+#Counter对象间可以做数学运算
+ca + cb  # Counter({'orange': 3, 'computer': 2, 'apple': 1})
+
+
+进一步抽象，实现多个列表内元素的个数统计
+
+
+def sumc(*c):
+    if (len(c) < 1):
+        return
+    mapc = map(Counter, c)
+    s = Counter([])
+    for ic in mapc: # ic 是一个Counter对象
+        s += ic
+    return s
+
+
+#Counter({'orange': 3, 'computer': 3, 'apple': 1, 'abc': 1, 'face': 1})
+sumc(a, b, ['abc'], ['face', 'computer'])
+
+```
diff --git a/md/README.md b/md/README.md
@@ -38,6 +38,7 @@
 18. [列表查重及次数](列表查重及次数.md)
 19. [多序列运算函数](多序列运算函数.md)
 20. [列表加字段标签](列表加字段标签.md)
+21. [联合统计多列表元素出现次数](Counter的高级用法.md)
 
 ####  四、字典
 
diff --git a/src/counter_add.py b/src/counter_add.py
@@ -0,0 +1,22 @@
+from collections import Counter
+a = ['apple', 'orange', 'computer', 'orange']
+b = ['computer', 'orange']
+
+ca = Counter(a)
+cb = Counter(b)
+ca + cb  # Counter({'orange': 3, 'computer': 2, 'apple': 1})
+
+
+# 进一步抽象
+def sumc(*c):
+    if (len(c) < 1):
+        return
+    mapc = map(Counter, c)
+    s = Counter([])
+    for ic in mapc:
+        s += ic
+    return s
+
+
+#Counter({'orange': 3, 'computer': 3, 'apple': 1, 'abc': 1, 'face': 1})
+sumc(a, b, ['abc'], ['face', 'computer'])
