Hey Brian:
I tried that as well, but to no avail . =[.
-Reza
> Hm,
>
> I don't know how equals() is implemented for Text, but I'd try:
>
> key.toString().equals("sex")
>
> Brian
>
> On Apr 19, 2009, at 11:29 AM, Reza wrote:
>
>> Brian:
>>
>> Thanks for your response.
>>
>> I have 8 total keys and values. The code I show below is part of the
>> whole
>> thing, just to illustrate my problem.
>>
>> Im trying to call each key with an if statement (as in the piece I
>> showed
>> before). Each of my 8 keys have their respective if statement.
>>
>> However, it seems that my if statement is not going through. I even
>> put
>> the output.collect(...) inside the if statement, and accordingly, no
>> output was shown. I already tested my mapper, and it seems to work
>> fine.
>>
>> I believe that I am having difficulty at this point:
>>
>> if (key.equals("sex")) {...}
>>
>> The key in this case is "sex" (or gender) and the possible values
>> are 0
>> (for male) and 1 (for female). Is this not the right way to separate
>> out
>> my keys?
>>
>> -Reza
>>
>>> Hey Reza,
>>>
>>> From reading your code, you are calling this for the key "sex":
>>>
>>> output.collect("The total population is: ", (actual population))
>>>
>>> and, for every other key:
>>>
>>> output.collect("The total population is: ", 0)
>>>
>>> You probably only want to call the output collector in the first
>>> case,
>>> not every time.
>>>
>>> Brian
>>>
>>>
>>> On Apr 18, 2009, at 12:21 PM, Reza wrote:
>>>
>>>> Hello all:
>>>>
>>>> I am new to Hadoop and Map Reduce. I am writing a program to analyze
>>>> some
>>>> census data.
>>>>
>>>> I have a general question with MapReduce:
>>>>
>>>> In the Reducer, how can I separate keys to do separate calculations
>>>> based
>>>> on the key? In my case, I am trying to use if statements to separate
>>>> the
>>>> keys out, but for some reason, it is not doing so.
>>>>
>>>> Here is a segment of my code. My mapper seems to work, I think it is
>>>> my
>>>> Reducer that is messing up:
>>>>
>>>> public static class MapClass extends MapReduceBase implements
>>>> Mapper<LongWritable, Text, Text, IntWritable> {
>>>>
>>>> // private final static IntWritable one = new IntWritable(1);
>>>> Text sex = new Text("sex");
>>>> public void map(LongWritable key, Text value,
>>>> OutputCollector<Text, IntWritable> output,
>>>> Reporter reporter) throws IOException {
>>>> String line = value.toString();
>>>> StringTokenizer itr = new StringTokenizer(line,",");
>>>>
>>>> :
>>>> :
>>>> word.set(itr.nextToken());
>>>> IntWritable sexVal = new
>>>> IntWritable(Integer.parseInt(word.toString())); //map gender
>>>> output.collect(sex, sexVal);
>>>>
>>>> }//end map()method
>>>> }//end class MapClass
>>>>
>>>>
>>>> public static class Reduce extends MapReduceBase
>>>> implements Reducer<Text, IntWritable, Text, IntWritable> {
>>>>
>>>>
>>>> public void reduce(Text key, Iterator<IntWritable> values,
>>>> OutputCollector<Text, IntWritable> output,
>>>> Reporter reporter) throws IOException {
>>>>
>>>> int totalPop = 0; //count: total population
>>>> int numMales = 0; //count: males
>>>> int numFemales = 0; //count: females
>>>> Text popOut = new Text("The total population is:
>>>> ");
>>>> if (key.equals("sex")) {
>>>> while (values.hasNext()) {
>>>> if (values.next().get() == 0)
>>>> numMales++; //number
>>>> of males
>>>> else
>>>> numFemales++; //number
>>>> of
>>>> females
>>>> }//end while
>>>> totalPop = numMales + numFemales; //count of
>>>> population
>>>> }//end if
>>>> output.collect(popOut, new IntWritable(totalPop));
>>>>
>>>> }//end reduce method
>>>> }//end class Reduce
>>>>
>>>> key is of type Text, I also used: if (key.toString() == "sex) {....
>>>> but that wasnt working either.
>>>>
>>>> There are of course other keys and values, but I would think to
>>>> gather all
>>>> the keys "sex" would be done with the way I show it above. However,
>>>> My
>>>> output reads as 0. I tried changing the numMales value to see if
>>>> the if
>>>> statement is executed, but it is not. Am I doing something wrong?
>>>>
>>>
>>>
>
>
