加载文件，使中的整个记录存储在1字段中。然后将行标记为字母。仅筛选逗号、组和计数逗号。

A = load '/home/user/fileX';
B = foreach A generate flatten(TOKENIZE(REPLACE($0,'','|'), '|')) as letter;
C = filter B BY (letter == ',');
D = group C by letter;
E = foreach D generate COUNT(C), group;--Note:if you want only the count then remove the group and generate COUNT(C)
DUMP E;

输出