CODEWITHSUNDEEP
matlabrowsfrequency
Kadin
Kadin

Reputation: 160

How do I find frequency of values appearing in all rows of a matrix in MATLAB?

I have a 161*32 matrix (labelled "indpic") in MATLAB and I'm trying to find the frequency of a given number appearing in a row. So I think that I need to analyse each row separately for each value, but I'm incredibly unsure about how to go about this (I'm only new to MATLAB). This also means I'm incredibly useless with loops and whatnot as well.

Any help would be greatly appreciated!

Upvotes: 0

Views: 1434

Answers (3)

fatihk
fatihk

Reputation: 7929

You can just write 

length(find(indpic(row_num,:)==some_value))

and it will give you the number of elements equal to "some_value" in the "row_num"th row in matrix "indpic"

Upvotes: 0

Eitan T
Eitan T

Reputation: 32930

If you want to count the number of times a specific number appears in each row, you can do this:

sum(indpic == val, 2)

where indpic is your matrix (e.g image) and val is the desired value to be counted.

Explanation: checking equality of each element with the value produces a boolean matrix with "1"s at the locations of the counted value. Summing each row (i.e summing along the 2nd dimension results in the desired column vector, where each element being equal to the number of times val is repeated in the corresponding row).

If you want to count how many times each value is repeated in your image, this is called a histogram, and you can use the histc command to achieve that. For example:

histc(indpic, 1:256)

counts how many times each value from 1 to 256 appears in image indpic.

Upvotes: 2

frickskit
frickskit

Reputation: 624

Like this,

sum(indpic(rownum,:) == 7)

obviously change 7 to whatever.

Upvotes: 0

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