21. MapReduce如何做字數統計
This is a book
This is a pen
This is a desk
That is my book
That is my pen
<This,3>
<That,2>
This is a desk
That is my book
map1
map2
map3
<This,1>, <is, 1>, <a, 1>, <book,1>
<This,1>, <is, 1>, <a, 1>, <pen,1>
<This,1>, <is, 1>, <a, 1>, <desk,1>
<That,1>, <is, 1>, <my, 1>, <book,1>
<That,1>, <is, 1>, <my, 1>, <pen,1>
reduce
<This,3>, <That,2>, <is, 5>, <my, 2>, <a,3>
<book,2>, <desk,1>, <pen,2>
<This, [1,1,1]>
<That,[1,1]>
<is,[1,1,1,1,1]>
<my,[1,1]>
<a,[1,1,1]>
<book,[1,1]>
<pen,[1,1]>
<desk,[1]>
<is,5>
<my,2>
<a,3>
map2
<book,2>
<desk,1>
<pen,2>
That is my pen
map3
This is a book
This is a pen
map1
26. 動手對資料做分類
國文 數學
ID 1 0 10
ID 2 10 0
ID 3 10 10
ID 4 20 10
ID 5 10 20
ID 6 20 20
ID 7 50 60
ID 8 60 50
ID 9 60 60
ID 10 90 90
國文 數學
ID 1 0 10
ID 2 10 0
ID 3 10 10
ID 4 20 10
ID 5 10 20
ID 6 20 20
ID 7 50 60
ID 8 60 50
ID 9 60 60
ID 10 90 90