how to plot histogram from an array ?

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noble amin
noble amin on 22 Dec 2021
Commented: Image Analyst on 22 Dec 2021
Hi everyone, what the simplest code to plot a histogram from this table ?
( x-axis for frequencies ; y-axis for the numbers )

Answers (2)

Image Analyst
Image Analyst on 22 Dec 2021
Try putting each of those into a vector. The x axis is actually Number, not frequency, and the bin heights (the counts) are actually the frequency. So you'd do
frequency = [3,9,13,21,9,4,1];
Number = linspace(11.945, 12.035, length(frequency));
bar(Number, frequency);
xlabel('Number');
ylabel('Frequency (count)')
grid on;
  1 Comment
Image Analyst
Image Analyst on 22 Dec 2021
@noble amin I don't know how you're getting your original numbers but there is a variety of ways to read them in from a text file, like readmatrix(), importdata(), csvread(), etc. Once you have the numbers, if you want to put them into a table variable type you can use table() like this:
frequency = [3,9,13,21,9,4,1];
Number = linspace(11.945, 12.035, length(frequency));
t = table(Number(:), frequency(:), 'VariableNames', {'Number', 'frequency'})
t = 7×2 table
Number frequency ______ _________ 11.945 3 11.96 9 11.975 13 11.99 21 12.005 9 12.02 4 12.035 1
bar(t.Number, t.frequency);
xlabel('Number');
ylabel('Frequency (count)');
grid on;

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the cyclist
the cyclist on 22 Dec 2021
Histograms start from the data before they have been binned. You just need a bar chart. If your data are stored in a MATLAB table named tbl, then
bar(tbl.Number,tbl.frequency)
You didn't really tell us how the data are stored, so you may need to manipulate the data first, to get it in the proper format.
  2 Comments
the cyclist
the cyclist on 22 Dec 2021
How is your data stored now? Can you upload a MAT file with the data? (Use the paperclip icon in the INSERT section of the toolbar.)
For your future reference, uploading an image of your data (as you did in your original question) is not very helpful.

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