apache-pig - Pig Script中的除数

Question

ch = LOAD 'ch.txt';
ch_all = GROUP ch ALL;
ch_count = FOREACH ch_all GENERATE COUNT(ch);

ca = LOAD 'ca.txt';
ca_all = GROUP ca ALL;
ca_count = FOREACH ca_all GENERATE COUNT(ca);

我有上面的猪脚本代码，它计算两个计数。现在我想将 ch_count 除以 ca_count 并将其存储在一个文件中。我怎么做？

Answer 1

在 Pig 中没有方便的方法来执行此操作，但JOIN可以帮助您：

猪：

ch = LOAD 'ch.txt';
ch_all = GROUP ch ALL;
ch_count = FOREACH ch_all GENERATE 'same' AS key, (DOUBLE) COUNT(ch) AS ct;

ca = LOAD 'ca.txt';
ca_all = GROUP ca ALL;
ca_count = FOREACH ca_all GENERATE 'same' AS key, (DOUBLE) COUNT(ca) AS ct;

ca_ch = JOIN ch_count BY key, ca_count BY key;

ca_ch_div = FOREACH ca_ch GENERATE ch_count::ct / ca_count::ct;

DUMP ca_ch_div;

输出：

(0.6666666666666666)

输入：

cat ch.txt 
1
2
cat ca.txt 
1
2
3