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How to create a dynamic array, by counting the content of my current array?

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eirini
eirini on 10 Dec 2015
Answered: amal laabidi on 8 May 2021 at 16:51
Hi Matlab friends,
I have an array: A=[1,1,0,0,0,0,1,1,1,0,0,0,1,1]
and I want to create to other (dynamic) arrays, where I will count how many continuous'1' and '0' I have. So, I want to create the new arrays: For '1': B=[2,3,2] For '0': C=[4,3]
Do you know how can I do it?
I would really appreciate your answer!!
Regards, Eirini

Answers (2)

arich82
arich82 on 10 Dec 2015
This is a variation on run length encoding.
Note that find(diff(A)) returns the index of the end of each phase (where a phase is a run of zeros or ones); also note that the last element in A will always be the end of a phase, as well as the element '0' (i.e. the element before A(1)).
Taking the diff of these indices tells you the length of each phase. Putting it all together:
rl = diff([0, find(diff(A)), numel(A)]); % run lengths
B = rl(1:2:end);
C = rl(2:2:end);
Note that whether B corresponds to 1 or 0 depends on A(1); you could either write an if statement to assign B and C accordingly, or do something more obfuscated to assign them automagically.
Please accept this answer if it helps, or let me know in the comments if I've missed something.
  1 Comment
arich82
arich82 on 10 Dec 2015
For completeness:
2 - A(1) returns 2 if A(1) == 0, and 1 if A(1) == 1|.
Conversely, 1 + A(1) returns 2 if A(1) == 1, and 1 if A(1) == 0.
Therefore, the following code automatically assigns the runlengths of ones to B, and zeros to C:
rl = diff([0, find(diff(A)), numel(A)]); % run lengths
B = rl((2-A(1)):2:end); % rl's of ones
C = rl((1+A(1)):2:end); % rl's of zeros

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amal laabidi
amal laabidi on 8 May 2021 at 16:51
How to create a dynamic table, to store values measured using a mpu6050 sensor in matlab?
I transfer the measured data using a mpu6050 sensor to the matlab to display it, how to create a table to sotcker this data?

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