How can I plot histogram using b as x value and k as bin values? plotting histogram error line 16

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Jackie 2015-9-1

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回答： Image Analyst 2015-9-2

load sizes2.txt
results= sizes2(:,1) 
n=size(sizes2,1) % num of rows 
a=sizes2(:,:)
b=sort(a)
y=log10(n)
k= 1+3.322*y %  is suggested number of class intervals and n is the number of values in the data set
fprintf('The suggested number of class intervals is %d\n', k );
x=range(b)
w=x/k         % width of class intervals 
fprintf('The suggested number of class intervals is %d\n', w)
k=8
hist(b,k)

Thank you

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dpb 2015-9-1

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I can't reproduce an error; I would simplify quite a lot, but I get no error...I did just paste the data from the text file into the command window as variable sizes. Whatever is causing the above error is somewhere else than in the above.

>> n=length(sizes);
>> k=1+3.322*log10(n)  % without rounding
k =
  8.3130
>> k1=fix(k); % truncate; use round() if to nearest integer
>> n=hist(sizes,k)  % with the non-integer value
n =
  58    51    27    11     4     4     2     2
>> m=hist(sizes,k1) % and the integer version...
m =
  58    56    22    14     2     3     2     2
>> sum(m)==sum(n)  % both get all the elements
ans =
   1
>> hist(sort(sizes),k1)  % and to so you don't need sort()
>> o=hist(sort(sizes),k1)
o =
  58    56    22    14     2     3     2     2
>>

I didn't delve into the code of hist to see just exactly what it's doing with the non-integer bins; clearly it also truncated to the integer number but it did modify the binning as can be seen comparing the two outputs.

But, it doesn't cause an indexing error (and it doesn't appear to be the problem in your case as you still got an error)

Oh; you haven't by chance inadvertently created a variable hist, have you? Try

clear hist

and then try again...or, to see before clear try

which hist

Jackie 2015-9-2

Hi, thank you so much for the clarification actually yeah I think at some point when I was trying to put this together I accidentally at some point put hist=... and later realized that this can't be done . Once I put clear hist the historgram was plotting as desired. Thank you again

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