How can i count how many time a number appears and for how long in a vector?

I have a vector like this

v=[+1 +1 +1 0 0 0 +1 +1 -1 -1 +1 0 0 -1 -1 +1 +1]

I want to count how many times each number appears and for how long. i mean, for example let's consider +1. it appears indivigually only 1 time, then it appears in couple 2 times, then it appear in triplet only 1 time and so on. Could someone help me? thank you!

[KALYAN ACHARJYA]

Here also

https://in.mathworks.com/matlabcentral/answers/469659-count-the-adjacent-same-elements-in-a-vector

Answer 1

[Jan]

Start with a run-length-encoding, e.g. by FileExchange: RunLength . If you do not have a C-Compiler installed, use RunLength_M of this submission. Then:

v = [+1 +1 +1 0 0 0 +1 +1 -1 -1 +1 0 0 -1 -1 +1 +1];
[Num, Len] = RunLength_M(v)

Now you have the values and the lengths of the repetitions. Nur you can use histcounts to count, how often each sequence appears. If this is not time-ciritical, a simple loop does it also:

uniqNum = unique(Num);
for aNum = uniqNum(:).'
    fprintf('Number: %d\n', aNum);
    LenList = Len(Num == aNum);
    uniqLenList = unique(LenList);
    for aLen = uniqLenList(:)'
        fprintf('  Block length: %d', aLen);
        fprintf(' : %d times.\n', sum(LenList == aLen));
    end
end

[salvatore vergine]

Thank you so much. It works but i need to create a vector for each number (so a vector for +1, one for 0 and one for -1) of the same length of v in which i have for every position the number of time it appears. I mean, position 1 indicates how many time the number appears individually, position 2 indicates how many times it appears coupled and so on.

For example, if I consider 0 the result of your code is

Number: 2

Block length: 2 : 1 times.

Block length: 3 : 1 times.

From this I'd like to obtain the vector

v0=[0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

Thank you so much again.

[Jan]

It is not exactly clear, what you want to obtain e.g. for the input [0 0 1 1 2 2 1 1]

[salvatore vergine]

For this vector, i want to obtain these 3 vectors (one for 0, one for 1 and one for 2):

v0=[0 1 0 0 0 0 0 0]

v1=[0 2 0 0 0 0 0 0]

v2=[0 1 0 0 0 0 0 0]

If the input vector was [0 1 1 2 1 1 1] the result would be:

v0=[1 0 0 0 0 0 0]

v1=[0 1 1 0 0 0 0]

v2=[1 0 0 0 0 0 0]

Thank you!!

[Jan]

I do not reliably recognize the relation between the inputs and outputs.

[salvatore vergine]

I try to explain it better. In each vector each column represents a pattern. For example, let s consider the number 1 and the input vector [0 1 1 2 1 1 1]. The result is the vector v1=[0 1 1 0 0 0 0] in which column 1 indicates how many times number 1 appears individually in the input vector (zero times in this case). Column 2 indicates how many times number 1 appears coupled in the input vector (only 1 as you can see). Column 3 indicates how many times number 1 appears as a triplet (only 1 too) and so on.

Another example with the input vector [0 1 1 0 1 1 0 1 2]. In this case the outpur vectors are:

v0=[3 0 0 0 0 0 0 0 0]

v1=[1 2 0 0 0 0 0 0 0]

v2=[1 0 0 0 0 0 0 0 0]

I hope I expressed myself better.