Count the number of occurances of an element using accumarray

5 次查看（过去 30 天）
Ms. Mat
Ms. Mat 2012-12-27
Now I am trying to find the occurance of an element in a vector using
sum(dta(:,size(dta,2))==3);
How can accumarray be used to find the frequency of elements ?
A = [7 11 2 3 4 5 4 7 7 2 1 4 1];
How can I get a result such as,
  • 7 3
  • 11 1
  • 2 2
  • 3 1
  • 4 2
and so on.
Thanks in Advance.
P.S: I looked through other threads, but did not understand how it worked. The example given was count = accumarray(A',1) and the result was a vector which was not clear to me.

请先登录，再回答此问题。

采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2012-12-27
编辑：Azzi Abdelmalek 2012-12-27
A = [7 11 2 3 4 5 4 7 7 2 1 4 1]
[a,b,c ]=unique(A,'stable')
out=[a' accumarray(c,1)]
  3 个评论
显示 1更早的评论
Ms. Mat
Ms. Mat 2013-1-12
what is this option 'stable'. I work with 2009 version. I dont have this option. Also could you please explain wat really the code is doing.
Thank You
Azzi Abdelmalek
Azzi Abdelmalek 2013-1-12
A = [7 11 2 3 4 5 4 7 7 2 1 4 1]
[a,b,c ]=unique(A) % you can remove 'stable'
% a is the array containing unique value but in sorted order
%a=[ 1 2 3 4 5 7 11], if you remove 'stable', the result will be sorted
%c=[6 7 2 3 4 5 4 6 6 2 1 4 1] gives the indices of each value of A in a
% for example the 2nd value 11 in A is the 7nth in a
out=[a' accumarray(c,1)], %the result is sorted
1 2
2 2
3 1
4 3
5 1
7 3
11 1

请先登录，再进行评论。

更多回答（1 个）

Sean de Wolski
Sean de Wolski 2012-12-27
I would use histc on the output vector c that you have above from unique()
Frankly you should be able to skip all of that altogether:
[uv, idx] = unique(A);
n = histc(A,uv);
nA = n(idx)
(not tested in ML)

类别

在 Help Center 和 File Exchange 中查找有关 Shifting and Sorting Matrices 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by