Find the length of a vector up to a certain value

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Holmbrero
Holmbrero 2022-6-7
评论： Holmbrero 2022-6-8
Hi!
I have a vector (SortN1250) which is 75558x1 with a range from 1:1000 and i want to extract the length of the vector at certain values (100:100:5000) and ad them to another vector. This is my code:
ProbdistPoredens(50,1)=zeros
for n=100:100:5000
ind = find(abs(SortB1250(:,1)<n));
lengthind=length(ind)
for i=1:50
ProbdistPoredens(i,1)=lengthind
end
end
ProbdistPoredens is however just filled with the number 75558 on all 50 rows. This number is only expeted to show at the very last row in the column.
Any suggestions would be greatly appriciated!
Regards,

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采纳的回答

Image Analyst
Image Analyst 2022-6-7
Explain in words what this means: (100:100:5000)
Do you want only elements that have values of 100, 200, 300, 400, ..., 4900, or 5000?
Is that what "at certain values" means? Or does it mean at certain indexes?
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Image Analyst
Image Analyst 2022-6-8
Ran in:
Try this:
% Create sample data.
SortB1250 = 1000 * rand(75558, 1);
ProbdistPoredens=zeros(50,1);
n = 100 : 100 : 5000
n = 1×50
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000
for k = 1 : length(n)
ind = find(SortB1250 < n(k));
ProbdistPoredens(k) = length(ind);
end
plot(ProbdistPoredens, 'b.-', 'lineWidth', 2)
grid on;

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更多回答（1 个）

Simon Chan
Simon Chan 2022-6-8
The inner for loop is not necessary and it overwrite itself for every 'n'.
You may modify the code as follows.
ProbdistPoredens(50,1)=zeros;
for n=100:100:5000
ind = find(abs(SortB1250(:,1)<n));
lengthind=length(ind);
ProbdistPoredens(n/100,1)=lengthind; % modify the index from i to n/100
end
Alternatively, you can use function histcounts to do the same thing.
[ProbdistPoredens,~] = histcounts(SortB1250,0:100:5000,'Normalization','cumcount') % Use function hiscounts

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