Extract data from a histogram from a certain range on the x-axis

I am trying extract data from a histogram on a certain range on the x-axis without going in individually and counting the 'binned' data using the data cursor. Is there any way on how to do this?

[Walter Roberson]

Was the histogram created with hist() or with histogram() ?

[jgillis16]

hist()

[Image Analyst]

Attach a diagram. I don't know what you mean. Do you have a 1-D vector of numbers, a 2-D image, or what? If you have just a 1-D list of numbers, then the "x" axis is just the index, and the "y" value is the value of the array, so what does a hist of the x-axis mean in that case? A histogram of the indexes would just be a vector of all 1's since each index appears just once. Even for a 2D array, I don't know what a "histogram on a certain range on the x-axis" means. Do you mean a histogram of image values only between column #1 and column #2?

Answer 1

[Walter Roberson]

The easiest way is to store the output of the hist() call, which will be the counts (or the counts and the centers if you have two outputs.) You can then bar() the graph into existence:

[counts, centers] = hist(YourData);
bar(centers, counts, 'hist');

Failing that, if you really need to pull data out of an existing hist(), then:

histpatch = findobj(gca, 'type', 'patch');
edgemat = get(histpatch, 'XData');
countmat = get(histpatch, 'YData');
counts = countmat(2,:);
centers = mean(edgemat(2:3,:));

[jgillis16]

Would this pull the data into an array that I could manipulate?

[Walter Roberson]

Yes the result is the vector "counts" and the vector "centers" which tells you what the totals were and where the bins were located respectively. You can make manipulate based on those. For example,

inrange = centers >= 4 & centers <= 12;
counts_inrange = counts(inrange);

[Avinash Bhatt]

what countmat(2,:) mean?

[Heejung Jung]

How do you do the same thing if histogram() was used instead of hist()?