A couple of pointers:
UDFs must declare the schema of their output.
See the documentation here:
http://pig.apache.org/docs/r0.8.0/udf.html#Schema
In Java UDFs, this is done by implementing Schema outputSchema(Schema input)
In Python you use the @outputSchema decorator providing the schema in the
format used in LOAD statements
See the schema documentation for reference:
http://pig.apache.org/docs/r0.8.0/piglatin_ref2.html#Schemas
Julien
On 1/7/11 5:42 AM, "Jonathan Coveney" <jcove...@gmail.com> wrote:
The words themselves have no meaning, as far as I know. What does matter is
that its a touple with one element, a double. In the case of x:{etc}, the
important thing is that pig knows it is a bag. The names are for us, not pig.
So in your own example, one function returns and actual bag, whereas the other
only tuples (that may go inyo a bag).
Sent via BlackBerry
-----Original Message-----
From: <deepak....@wipro.com>
Date: Fri, 7 Jan 2011 18:29:03
To: <user@pig.apache.org>
Reply-To: user@pig.apache.org
Subject: Meaning of outputSchema - Python UDF
Hi,
I don't seem to understand the OutputSchema constructs given in the
documentation.
What is the significance of the letters 'x', 't', and the parentheses '{}' &
'()'
@outputSchema("x:{t:(word:chararray)}")
For instance, the following looks different
#Percent- Percentage
@outputSchema("t:(percent:double)")
def percent(num, total):
return num * 100 / total
Apologies if my question sounds dumb.
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