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boxplot

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New
New on 13 Mar 2012
Commented: Benoit Espinola on 10 Jun 2020
I have a matrix of occurences (7 rows(countries),46 columns(number of shoes)), n - number of occurences - for example in "a" I have n1=450, single pair of shoes...
1 2 3 .... 46
a n1 n2 n3 .... n46
b
.
. . g
I would like to produce 7 boxplots representing the distribution in each category a-g. Normally I would have 450 times 1, n2 times 2 etc... is there a simple way to do it? Does anybody have a suggestion for a nicer representation than the boxplot?
Thank you

Accepted Answer

Tom Lane
Tom Lane on 16 Mar 2012
This may partially answer what you want. Step 1 would be to take the data for "a" and stretch it out as you describe. Here's one way to expand a data vector according to a vector of frequencies:
f = [4 3 0 1 2]; % frequencies
d = [1 2 3 4 5]; % data
c = [0, cumsum(f)]; % cumulative sum of frequencies
x = zeros(1,c(end));
for j=1:length(c)-1
x(c(j)+1:c(j+1)) = d(j); % insert each value as required
end
  2 Comments
Benoit Espinola
Benoit Espinola on 10 Jun 2020
This could become an issue if you have very large frequencies.
For instance:
d = [1 2 3 4 5];
f = [4e10 3e9 0 1e10 2e11];
You could endup with a variable with a length of 2.53e11 (which is massive).
I tried it and I get the following error:
Error using zeros
Requested array exceeds the maximum possible variable size.
How can you deal with such a scenario?

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More Answers (1)

Tom Lane
Tom Lane on 14 Mar 2012
It seems like 1:46 represents your possible data values and [n1 n2 ... n46] represents the frequency of each value. If you "edit mle" and look toward the bottom, it has a little function that expands this sort of representation into a vector with n1 copies of 1, n2 copies of 2, and so on. You could try copying this code to your own function. A warning is that you will need to remove values with a frequency of zero before calling the function.
If you're not comfortable doing this, or if I haven't answered your question, let me know.
  1 Comment
New
New on 15 Mar 2012
Couldn't make it work properly...
Some easier way?
Thanks

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