Apache pig 1元组的展平和计数

count_bool是一个单元组，在我转储它时有以下输出：

(0)  
...  
(1)  
(0)  
...  
(0)  

如果有100-（0）和20-（1），我希望输出为：

(1, 20)
(0, 100)

这是我尝试的平展和计数

count_by_xy = foreach count_by_subject generate flatten($0), COUNT($0);  
2013-07-09 00:05:43,590 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1045:  
Could not infer the matching function for org.apache.pig.builtin.COUNT as multiple or none of them fit. Please use an explicit cast.  

---

我有什么问题

“colName”是分配给1元组列的名称：

count_group = group count_bool by colName;

“结果”是我想要的：

result = foreach count_group generate $0, COUNT(count_bool);

$0

引用第一列的值

flatte

用于取消嵌套元组，此处不需要嵌套元组