如何将1x1别名变为标量？

Question

我想将计数转化为概率：

total = foreach (group A all) generate SUM(A.count);
A = foreach A generate A.count / total as probability;

这不起作用，因为total是别名，而不是标量：

  

标量投影无效：总计：需要投射一列   它被用作标量的关系

Answer 1

即使别名total只有一个字段（总和），您仍然需要引用该字段。

这应该有效：

total = foreach (group A all) generate SUM(A.count) as total;
A = foreach A generate A.count / total.total as probability;

Answer 2

试试这个

total = foreach (group A all) generate SUM(A.count) as total_sum;
A = foreach A generate count / (int)total.total_sum as probability;

此处http://pig.apache.org/docs/r0.11.1/basic.html#cast 搜索“向Scalars投射关系”