convert an array into its counting sequence..

5 次查看(过去 30 天)
i want to convert an array into its counting sequence. for example
if the input is :
x = [1 1 4 4 6 7]
two 1's two 4's one 6 one 7...
output must be :
y=[2 1 2 4 1 6 1 7]
can anyone help?

回答(2 个)

madhan ravi
madhan ravi 2019-8-2
编辑:madhan ravi 2019-8-2
According to what I understand you want to count the number of occurances of each unique elements in the array x, then:
x = [1 1 4 4 6 7];
[u,~,idx]=unique(x);
v=accumarray(idx,1);
y=reshape([v,u(:)].',1,[])
Gives:
y =
2 1 2 4 1 6 1 7
  2 个评论
Jos (10584)
Jos (10584) 2019-8-2
This fails for inputs like [1 1 2 1 1], where values are repeated.
I admit, the question is a little unclear, but "counting sequence" suggests, at least to me, more than just counting ;-)

请先登录,再进行评论。


Jos (10584)
Jos (10584) 2019-8-2
This is called run-length encoding, for which there are very efficient functions available on the File Exchange.
I point you to my own function RUNINDEX which can also return this:
[~, RLE] = runindex(x)
y = reshape(RLE(:,[3 1]).', 1, []) % your format

类别

Help CenterFile Exchange 中查找有关 Mathematics 的更多信息

Community Treasure Hunt

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

Start Hunting!

Translated by