How do I get a sum of column two if the value in column one is the same?

1 次查看（过去 30 天）
Humblespud
Humblespud 2016-8-18
评论： Star Strider 2016-8-18
How do I get a sum of column two if the value in column one is the same? The values below represent a segment of a much larger dataset
31128 166 31128 27 31128 0 31128 276 31128 0 31201 0 31201 2125 31201 0 31201 56 31201 0 31201 0 31201 0 31201 0 31235 2125 31235 13 31235 364 31235 1836 31235 379 31235 486

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2016-8-18
编辑：Star Strider 2016-8-18
Use the unique and accumarray functions:
A = [31128 166
31128 27
31128 0
31128 276
31128 0
31201 0
31201 2125
31201 0
31201 56
31201 0
31201 0
31201 0
31201 0
31235 2125
31235 13
31235 364
31235 1836
31235 379
31235 486];
[A1u,ia,ic] = unique(A(:,1));
A2sum = accumarray(ic, A(:,2));
Result = [A1u A2sum]
Result =
31128 469
31201 2181
31235 5203
  2 个评论
Star Strider
Star Strider 2016-8-18
The code works by first getting the unique values in ‘A(:,1)’ and returns them in ‘A1u’. The ‘ic’ vector are the positions in ‘A(:,1)’ that correspond to each of them, so a 1 in ‘ic’ corresponds to an occurrence of ‘31128’, a 2 to ‘31201’, and so for the rest (since I assume there will be more).
The accumarray call uses the indices returned in ‘ic’ to accumulate (sum) the corrsponding values in ‘A(:,2)’, and returns that vector in ‘A2sum’. (See the documentation for accumarray for the details of all it can do.)
The ‘Result’ assignment concatenates ‘A1u’ and ‘A2sum’ to form a sort of table to make the output easier to interpret.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Just for fun 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by