Ah, as I said before, I have no experience at programming MapReduce. So,
can you give me some documents or websites or something about programming
the thing you said above? ("Thousand things start hard" - VietNam)
Thanks so much ^^!Vào 10:54 Ngày 24 tháng 4 năm 2012, Lac Trung <trungnb3...@gmail.com> đã viết: > Thanks Jay so much ! > I will try this. > ^^ > > Vào 10:52 Ngày 24 tháng 4 năm 2012, Jay Vyas <jayunit...@gmail.com> đã > viết: > > Ahh... Well than the key will be teacher, and the value will simply be >> >> <-1 * # students, class_id> . >> >> Then, you will see in the reducer that the first 3 entries will always be >> the ones you wanted. >> >> On Mon, Apr 23, 2012 at 10:17 PM, Lac Trung <trungnb3...@gmail.com> >> wrote: >> >> > Hi Jay ! >> > I think it's a bit difference here. I want to get 30 classId for each >> > teacherId that have most students. >> > For example : get 3 classId. >> > (File1) >> > 1) Teacher1, Class11, 30 >> > 2) Teacher1, Class12, 29 >> > 3) Teacher1, Class13, 28 >> > 4) Teacher1, Class14, 27 >> > ... n ... >> > >> > n+1) Teacher2, Class21, 45 >> > n+2) Teacher2, Class22, 44 >> > n+3) Teacher2, Class23, 43 >> > n+4) Teacher2, Class24, 42 >> > ... n+m ... >> > >> > => return 3 line 1, 2, 3 for Teacher1 and line n+1, n+2, n+3 for >> Teacher2 >> > >> > >> > Vào 09:52 Ngày 24 tháng 4 năm 2012, Jay Vyas <jayunit...@gmail.com> đã >> > viết: >> > >> > > Its somewhat tricky to understand exactly what you need from your >> > > explanation, but I believe you want teachers who have the most >> students >> > in >> > > a given class. So for English, i have 10 teachers teaching the class >> - >> > and >> > > i want the ones with the highes # of students. >> > > >> > > You can output key= <classid>, value=<-1*#ofstudent,teacherid> as the >> > > values. >> > > >> > > The values will then be sorted, by # of students. You can thus pick >> > > teacher in the the first value of your reducer, and that will be the >> > > teacher for class id = xyz , with the highes number of students. >> > > >> > > You can also be smart in your mapper by running a combiner to remove >> the >> > > teacherids who are clearly not maximal. >> > > >> > > On Mon, Apr 23, 2012 at 9:38 PM, Lac Trung <trungnb3...@gmail.com> >> > wrote: >> > > >> > > > Hello everyone ! >> > > > >> > > > I have a problem with MapReduce [:(] like that : >> > > > I have 4 file input with 3 fields : teacherId, classId, >> numberOfStudent >> > > > (numberOfStudent is ordered by desc for each teach) >> > > > Output is top 30 classId that numberOfStudent is max for each >> teacher. >> > > > My approach is MapReduce like Wordcount example. But I don't know >> how >> > to >> > > > determine key for map function. >> > > > I run Wordcount example, understand its code but I have no >> experience >> > at >> > > > programming MapReduce. >> > > > >> > > > Can anyone help me to resolve this problem ? >> > > > Thanks so much ! >> > > > >> > > > >> > > > -- >> > > > Lạc Trung >> > > > 20083535 >> > > > >> > > >> > > >> > > >> > > -- >> > > Jay Vyas >> > > MMSB/UCHC >> > > >> > >> > >> > >> > -- >> > Lạc Trung >> > 20083535 >> > >> >> >> >> -- >> Jay Vyas >> MMSB/UCHC >> > > > > -- > Lạc Trung > 20083535 > > -- Lạc Trung 20083535
