在猪中逃脱美元符号? [英] Escaping a Dollar Sign in Pig?

问题描述

在0.9.2中这不是问题，但在0.10中，当我尝试访问其中带有美元符号的映射中的键时，我为自己未定义变量的错误而感到困惑.具体来说:

This wasn't a problem in 0.9.2, but in 0.10, when I try to access a key in a map that has a dollar sign in it, I get hammered with errors that I haven't defined the variable. Specifically:

blah = FOREACH meh GENERATE source, json_post_id#'$id' AS post_id;

返回

Undefined parameter : id

这很好并且很有意义，但是当我将其修改为:

That's fine and makes sense, but when I amend it to:

blah = FOREACH meh GENERATE source, json_post_id#'\$id' AS post_id;

我得到:

Unexpected character '$'

想法?

忘了提及:尝试过2个反斜杠和3个反斜杠.没有骰子. [/编辑]

Forgot to mention: have tried with 2 backslashes and 3 backslashes as well. No dice. [/Edit]

推荐答案

1. 基于对邮件存档的回复发布，看起来行为在使用Grunt shell并将其作为脚本运行时会有所不同."

1. Based on a response to your Mail Archive Posting, it looks like the behavior will be "different when using Grunt shell and running it as a script."

输入文件

cheolsoo@localhost:~/workspace/pig-svn $cat 1.txt $id,a

硬壳

没有反斜杠的$起作用:

grunt> A = LOAD '1.txt' USING PigStorage(',') AS (k:chararray,
v:chararray); grunt> B = FOREACH A GENERATE TOMAP(k, v) AS M; grunt> C
= FOREACH B GENERATE M#'$id'; grunt> DUMP C; (a)

脚本

带有单个反斜杠的$起作用:

The $ with a single backslash works:

cheolsoo@localhost:~/workspace/pig-svn $cat test.pig A = LOAD '1.txt' 
USING PigStorage(',') AS (k:chararray, v:chararray); B = FOREACH A
GENERATE TOMAP(k, v) AS M; C = FOREACH B GENERATE M#'\$id'; DUMP C;

cheolsoo@localhost:~/workspace/pig-svn $./bin/pig -x local test.pig
(a)

此外，来自>带分割字符串(STRSPLIT)的猪问题，您是否尝试过以下任何一种方法?

Also, from Pig problem with split string(STRSPLIT), have you tried either of the following.

• 正确地转义了字符u0024.使用单引号或双引号测试单引号，以查看是否有区别. 此答案表明单引号会有所不同，但值得一提.

• Correctly escaping the character u0024. Test single using single or double quotes to see if that makes a difference. This answer shows that the single quote makes a difference which you have but it's worth mentioning.

或者，尽管相关，但将循环分成一个块.

Alternatively, although related, break the loop into a block.

blah = FOREACH meh {
    GENERATE source, json_post_id#'$id' AS post_id; 
}

您似乎正在连接id.确保您不打算使用CONCAT(). http://pig.apache.org/docs/r0.10.0/func.html#concat

It looks like you are concatenating an id. Make sure you are not suppose to be using CONCAT(). http://pig.apache.org/docs/r0.10.0/func.html#concat

根据Class PigStorage文档(Pig 0.10.0 API):

According to the Class PigStorage documentation (Pig 0.10.0 API):

一个加载函数，它使用字符定界符将输入的行解析为字段.默认的分隔符是制表符.您可以将任何字符指定为文字("a")，已知的转义字符("\ t")或dec或hex值("\ u001"，"\ x0A").

A load function that parses a line of input into fields using a character delimiter. The default delimiter is a tab. You can specify any character as a literal ("a"), a known escape character ("\t"), or a dec or hex value ("\u001", "\x0A").

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