hi, my array=[ 1 2 4 5 16 18 21 28 36 38..............], i need to find max value within every 10 numbers,(i.e, my answers=[5 18 28 38...............]).

i dont know to explain clearly in english, sorry.

[kaavya subramani]

plz help me with matlab code

Answer 1

[Walter Roberson]

I suspect that you want a sliding maximum. One way to do that is

max( buffer(data, 10))

Another way is to use the image processing toolbox morphological routines. I seem to recall that dilation corresponds to max but I could be mistaken.

You could also loop.

[Guillaume]

Or, since 2016a, use movmax

movmax(buffer, 10)

[Walter Roberson]

Thanks, Guillaume, I went looking for such a function but could not find it; it is not cross-linked in the moving average routines.

[kaavya subramani]

S sir, u r right, i have already used variable named as "max", actually my code is too long, thatsy it takes long time to identify the errror

Answer 2

[KSSV]

data = rand(1,100) ;  % some random data 
data1 = reshape(data,10,[]) ;  % reshape to matrix with 10 rows 
val = max(data1) ;  % get maximum

[kaavya subramani]

Sir my total number of elements in array is 146,i getting an error as Error using reshape Product of known dimensions, 10, not divisible into total number of elements, 146.

[KSSV]

data = rand(1,146) ;  % some random data 
% remove extra elements not divisvibely by 10
extra = mod(146,10) ;
data1 = data(1:end-extra) ;
data1 = reshape(data1,10,[]) ;  % reshape to matrix with 10 rows 
val = max(data1) ;  % get maximum 
% get maximum of extra elements 
max_extra = max(data(extra:end)) ;
% attach it to the maximums 
val = [val max_extra] ;

[kaavya subramani]

i got error as "Subscript indices must either be real positive integers or logicals". how to rectify this?

[KSSV]

You can run the same code for your 1x146 data. It should not throw any error. Why you got that error? Post the code here.

[kaavya subramani]

I am getting error at val = "max(data1) ;". my data is 1x146 double.

[KSSV]

data = rand(1,146) ;  % some random data

I have taken 1x146 data only. You have to replace this data with your data. How is your data? In text file? Attach here.

[kaavya subramani]

i have attached my data here

[KSSV]

% data = rand(1,146) ;  % some random data 
data = importdata('data.txt') ;
% remove extra elements not divisvibely by 10
extra = mod(146,10) ;
data1 = data(1:end-extra) ;
data1 = reshape(data1,10,[]) ;  % reshape to matrix with 10 rows 
val = max(data1) ;  % get maximum 
% get maximum of extra elements 
max_extra = max(data(extra:end)) ;
% attach it to the maximums 
val = [val max_extra] ;

[kaavya subramani]

Ok sir, anyway thanks for ur time, i try my whole code in some other matlab version

[Walter Roberson]

That error about subscript indices tells us that you created a variable named max. If you have a variable named max then you can not call the MATLAB max() routine in the same scope.