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Hadoop >> mail # user >> Re: Provide context to map function


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Re: Provide context to map function
protected void map(KEYIN key, VALUEIN value,
                     Context context) throws IOException,
InterruptedException {
    context.write((KEYOUT) key, (VALUEOUT) value);
  }

Context is a parameter that the execute environment will pass to the map()
function.
You can just use it in the map() function.
2013/4/2 Abhinav M Kulkarni <[EMAIL PROTECTED]>

>  To be precise, I am using Hadoop 1.0.4.
>
> There is no local variable or argument named context in the map function.
>
> Thanks,
> Abhinav
>
>
> On 04/01/2013 09:06 PM, Azuryy Yu wrote:
>
>   I supposed your input splits are FileSplit, if not, you need to:
>
>  InputSplit split = context.getInputSplit();
>
>  if (split instanceof FileSplit){
>    Path path = ((FileSplit)split).getPath();
> }
>
>
>
>
> On Tue, Apr 2, 2013 at 12:02 PM, Azuryy Yu <[EMAIL PROTECTED]> wrote:
>
>>  In your map function add following:
>>
>> Path currentInput = ((FileSplit)context.getInputSplit()).getPath();
>>
>>  then:
>>
>>  if (currentInput is first ){
>> ................
>> }
>>  else{
>> ..................
>> }
>>
>>
>>
>>
>> On Tue, Apr 2, 2013 at 11:55 AM, Abhinav M Kulkarni <
>> [EMAIL PROTECTED]> wrote:
>>
>>>  Hi,
>>>
>>> I have a following scenario:
>>>
>>>
>>>    - Two mappers (acting on two different files) and one reducer
>>>    - The mapper code for two different files is the same, except for
>>>    minor change which depends on which file is being read
>>>    - Essentially assume there is an if statement - if first file is
>>>    being read do this else do this
>>>
>>> So how do I provide this context to map function i.e. file name or say a
>>> boolean flag variable indicating the file being read?
>>>
>>> Thanks,
>>> Abhinav
>>>
>>
>>
>
>
+
Dino Kečo 2013-04-02, 08:20
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB