# Histogram to a CDF/PDF

조회 수: 49(최근 30일)
Sclay748 2020년 8월 24일
댓글: Sclay748 2020년 8월 24일
Hello, This is a screenshot of a table I have constructed for work.
Just to play it safe, I blacked out the column names, though it would be hard to assume anything with just 7 rows of the table to go off of. We will call the 5 fields "column1, column2, etc."
So I am able to create the hisogram of any of the columns, besides 3, but that isn't needed because it is all '94'.
I do:
histogram([a(1:135756).column1])
and the histogram works perfectly.
How would I do a CDF or PDF of this data?
I have tried:
histogram([a(1:135756).column1],'Normalization',pdf)
or
histogram([a(1:135756).column1],'Normalization',cdf)
but nothing changes from the original histogram.
Thank you!

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### 채택된 답변

Bruno Luong 2020년 8월 24일
편집: Bruno Luong 2020년 8월 24일
A=[a(1:135756).column1];
figure
subplot(2,1,1);
histogram(A,'Normalization','pdf');
ylabel('pdf');
subplot(2,1,2);
histogram(A,'Normalization','cdf');
ylabel('cdf');
##### 댓글 수: 1표시숨기기 없음
Sclay748 2020년 8월 24일
ahhhh beautiful.
Thank you!

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### 추가 답변(1개)

Alan Stevens 2020년 8월 24일
You can get a CDF as follows:
% Modified Kaplan-Meier CDF
% assumes each point is representative of 1/N of the population.
a = sort(a(:,1)); % so all the data for a are sorted in ascending order
N = length(a);
for k = 1:N
CDF(k) = (k - 0.5)/N;
end
plot(a,CDF)
Because you have a large number of points you could simply numerically differentiate the CDF to get a PDF.
##### 댓글 수: 4표시숨기기 이전 댓글 수: 3
Sclay748 2020년 8월 24일
Bruno, that worked. Is it supposed to be a single curved line?
I thought it would still plot the bars, but arranged by CDF. Or that is atleast how my boss's turned out when he showed me an example using histogram(......,'Normalization',cdf)

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R2020a

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