Re: Custom Iterator output
Thanks Dylan for the help. It helped me a lot.
On 18-Apr-2015 10:43 am, Dylan Hutchison dhutc...@mit.edu wrote:
Hi Vaibhav,
It sounds like you want to emit a single value that is a function of all
the entries in the parent iterator. In that case, the following template
should solve your problem, using the example of summing Values interpreted
as Longs:
/**
* Emit one value that is a function of entries from the parent iterator.
*/
public class SingleOutputIterator extends WrappingIterator {
private static final TypedValueCombiner.EncoderLong encoder = new
LongCombiner.StringEncoder();
private Key emitKey;
private Value emitValue;
@Override
public void seek(Range range, CollectionByteSequence columnFamilies,
boolean inclusive) throws IOException {
super.seek(range, columnFamilies, inclusive);
myFunction();
}
/**
* Reads all entries from the parent iterator, computing the value you want
to emit.
* Example given is summing the Values of parent entries, interpreted as
Longs.
*/
private void myFunction() throws IOException {
Long val = 0l;
while (super.hasTop()) {
val += encoder.decode(super.getTopValue().get());
super.next();
}
emitKey = new Key(); // replace this with the key you want to emit
emitValue = new Value(encoder.encode(val));
}
@Override
public Key getTopKey() {
return emitKey;
}
@Override
public Value getTopValue() {
return emitValue;
}
@Override
public boolean hasTop() {
return emitKey != null;
}
@Override
public void next() throws IOException {
emitKey = null;
emitValue = null;
}
}
Regards,
Dylan Hutchison
On Fri, Apr 17, 2015 at 8:05 PM, vaibhav thapliyal
vaibhav.thapliyal...@gmail.com wrote:
Hi,
I also had this query that might be similar to shweta.
What I want to do is process the key value pairs that I get from
getTopKey() and getTopValue() methods and I want to output that value.
Currently I was writing these values to tables from inside the iterators,
but I read in the new manual that says that doing this isn't a good
practice.
For eg:
If I have these entries in my table:
1 cf1:cq1 value1
2 cf2:cq2 value2
3 cf3:cq3 value3
And suppose I sum the values(or do any opeation) of the row ids using the
values that I get from the getTopKey().getRow() function and store this sum
in a variable called sum.
So I want to output this variable. How do I go about this?
Thanks
Vaibhav
On 17-Apr-2015 6:40 pm, dlmar...@comcast.net wrote:
via the getTopKey() and getTopValue() methods. [1] should be a simple
example.
[1]
https://git-wip-us.apache.org/repos/asf?p=accumulo.git;a=blob;f=core/src/main/java/org/apache/accumulo/core/iterators/user/GrepIterator.java;h=043a729a778fc34d2ee87a0227056ffac81b7fe7;hb=refs/heads/master
--
*From: *shweta.agrawal shweta.agra...@orkash.com
*To: *user@accumulo.apache.org
*Sent: *Friday, April 17, 2015 8:50:26 AM
*Subject: *Custom Iterator output
Hi,
I am working on custom iterator. I want to know, how do i get the output
from the custom iterators?
Thanks and Regards
Shweta
Re: Custom Iterator output
via the getTopKey() and getTopValue() methods. [1] should be a simple example. [1] https://git-wip-us.apache.org/repos/asf?p=accumulo.git;a=blob;f=core/src/main/java/org/apache/accumulo/core/iterators/user/GrepIterator.java;h=043a729a778fc34d2ee87a0227056ffac81b7fe7;hb=refs/heads/master - Original Message - From: shweta.agrawal shweta.agra...@orkash.com To: user@accumulo.apache.org Sent: Friday, April 17, 2015 8:50:26 AM Subject: Custom Iterator output Hi, I am working on custom iterator. I want to know, how do i get the output from the custom iterators? Thanks and Regards Shweta
Re: Custom Iterator output
Hi Vaibhav,
It sounds like you want to emit a single value that is a function of all
the entries in the parent iterator. In that case, the following template
should solve your problem, using the example of summing Values interpreted
as Longs:
/**
* Emit one value that is a function of entries from the parent iterator.
*/
public class SingleOutputIterator extends WrappingIterator {
private static final TypedValueCombiner.EncoderLong encoder = new
LongCombiner.StringEncoder();
private Key emitKey;
private Value emitValue;
@Override
public void seek(Range range, CollectionByteSequence
columnFamilies, boolean inclusive) throws IOException {
super.seek(range, columnFamilies, inclusive);
myFunction();
}
/**
* Reads all entries from the parent iterator, computing the value
you want to emit.
* Example given is summing the Values of parent entries,
interpreted as Longs.
*/
private void myFunction() throws IOException {
Long val = 0l;
while (super.hasTop()) {
val += encoder.decode(super.getTopValue().get());
super.next();
}
emitKey = new Key(); // replace this with the key you want to emit
emitValue = new Value(encoder.encode(val));
}
@Override
public Key getTopKey() {
return emitKey;
}
@Override
public Value getTopValue() {
return emitValue;
}
@Override
public boolean hasTop() {
return emitKey != null;
}
@Override
public void next() throws IOException {
emitKey = null;
emitValue = null;
}
}
Regards,
Dylan Hutchison
On Fri, Apr 17, 2015 at 8:05 PM, vaibhav thapliyal
vaibhav.thapliyal...@gmail.com wrote:
Hi,
I also had this query that might be similar to shweta.
What I want to do is process the key value pairs that I get from
getTopKey() and getTopValue() methods and I want to output that value.
Currently I was writing these values to tables from inside the iterators,
but I read in the new manual that says that doing this isn't a good
practice.
For eg:
If I have these entries in my table:
1 cf1:cq1 value1
2 cf2:cq2 value2
3 cf3:cq3 value3
And suppose I sum the values(or do any opeation) of the row ids using the
values that I get from the getTopKey().getRow() function and store this sum
in a variable called sum.
So I want to output this variable. How do I go about this?
Thanks
Vaibhav
On 17-Apr-2015 6:40 pm, dlmar...@comcast.net wrote:
via the getTopKey() and getTopValue() methods. [1] should be a simple
example.
[1]
https://git-wip-us.apache.org/repos/asf?p=accumulo.git;a=blob;f=core/src/main/java/org/apache/accumulo/core/iterators/user/GrepIterator.java;h=043a729a778fc34d2ee87a0227056ffac81b7fe7;hb=refs/heads/master
--
*From: *shweta.agrawal shweta.agra...@orkash.com
*To: *user@accumulo.apache.org
*Sent: *Friday, April 17, 2015 8:50:26 AM
*Subject: *Custom Iterator output
Hi,
I am working on custom iterator. I want to know, how do i get the output
from the custom iterators?
Thanks and Regards
Shweta
Re: Custom Iterator output
Hi, I also had this query that might be similar to shweta. What I want to do is process the key value pairs that I get from getTopKey() and getTopValue() methods and I want to output that value. Currently I was writing these values to tables from inside the iterators, but I read in the new manual that says that doing this isn't a good practice. For eg: If I have these entries in my table: 1 cf1:cq1 value1 2 cf2:cq2 value2 3 cf3:cq3 value3 And suppose I sum the values(or do any opeation) of the row ids using the values that I get from the getTopKey().getRow() function and store this sum in a variable called sum. So I want to output this variable. How do I go about this? Thanks Vaibhav On 17-Apr-2015 6:40 pm, dlmar...@comcast.net wrote: via the getTopKey() and getTopValue() methods. [1] should be a simple example. [1] https://git-wip-us.apache.org/repos/asf?p=accumulo.git;a=blob;f=core/src/main/java/org/apache/accumulo/core/iterators/user/GrepIterator.java;h=043a729a778fc34d2ee87a0227056ffac81b7fe7;hb=refs/heads/master -- *From: *shweta.agrawal shweta.agra...@orkash.com *To: *user@accumulo.apache.org *Sent: *Friday, April 17, 2015 8:50:26 AM *Subject: *Custom Iterator output Hi, I am working on custom iterator. I want to know, how do i get the output from the custom iterators? Thanks and Regards Shweta
