[Solved-1 Solution] Understanding map syntax in pig
What is TOMAP() ?
- The TOMAP() function of Pig Latin is used to convert the key-value pairs into a Map.
We created a file containing the following text:
We are able to load that file without errors:
a = load 'data/file_name.txt' as (M:map )
Now, how to take the list of all the "values" ? I.e.
- There is only one way to interact with a map, and that is to use the # operator. In order for it to have more functionality define some UDFs. Therefore the only way a map can really be used in pure pig is like:
Which produces this as output:
- Note that the value after the # is a quoted string, it cannot change and must be set before we run the job.
- Also, notice that is creates a NULL for the second line, because that map does not contain a key with the vaule 'open'.
- This is slightly different then using FILTER on a schema of two chararrays key and value:
Which produces the output :
If only the value is desired, then it can be done simply by:
If keeping the NULLs is important, they can also be generated by using a bincond
Which produces the same output as