[erlang-questions] Reduce phase in erlang

Gopi Krishna <>
Tue Aug 5 14:24:47 CEST 2014


Hi,

I am working on riak database ,

I am having data in a riak bucket for a key like:

<<"{\"META\": {\"campaign\": \"5IVUPHE42HP1NEYvKb7qSvpX2Cm\",
          \"createdat\": 1406978070.0,
          \"user_email\": \"\"},
 \"mode\": 2,
 \"status\": \"success\"}">>

I have written a map phase which is giving data like

[<<"{<<"5IVUPHE42HP1NEYvKb7qSvpX2Cm">>,1}">>,
<<"{<<"WL6iHLCgs492rFEFvqewzvCfFfj">>, 2}">>,
<<"{"5IVUPHE42HP1NEYvKb7qSvpX2Cm">>, 1}">>,
<<"{<<"5IVUPHE42HP1NEYvKb7qSvpX2Cm">>, 2}">>]

so for the above data from mapphase i have to write a reduce phase that
should give depending on a condition like if it {key,Vlaue} if value is 0
or 1 then i have to to add new variable like ab_leads and it should
increment

I have tried like this this but the reducefunction should have more number
of functions according to [oldlist++newlist]

 <http://chat.stackoverflow.com/transcript/message/18089061#18089061>
lists:foldl(fun({Key,Mode},Acc) -> if Mode == 0;Mode == 1 ->
orddict:update_counter({Key,<<"ab_leads">>},1,Acc); true ->
orddict:update_counter({Key,<<"cp_leads">>},1,Acc) end end,orddict:new(),G).


[{{Key,{<<"ab_leads">>,10},{<<"cp_leads">>,20}},{Key1,{{<<"ab_leads">>,15},{<<"cp_leads">>,15}}].


please suggest me


-- 

Thanks & Regards,
J.Gopi Krishna
+91-8341452934,
www.lintelindia.com
Lintel Technologies Pvt. LTD,Hyderabad.

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