finding the increase in values

suppose i have a column matrix a=( 2 2 2 3 3 3 5 5 5 4 4 3 3 3 2 2 3 3 3 4 4 4 5 5 5 4 4 3 3 )

i want to find the constant and increasing elements and put them separately in different columns of a matrix. eliminating the decreasing elements.

output(:,1) = ( 2 2 2 3 3 3 5 5 5 )

output(:,2) = (2 2 3 3 3 4 4 4 5 5 5 )

Answer 1

[Stephen23]

a = [2;2;2;3;3;3;5;5;5;4;4;3;3;3;2;2;3;3;3;4;4;4;5;5;5;4;4;3;3]
idx = [true;diff(a)~=0];
idy = diff(a(idx))>0;
idd = diff([0;idy;0]);
idb = find(idd>0);
ide = find(idd<0);
ids = cumsum(idx);
fun = @(b,e)a(ismember(ids,b:e));
C = arrayfun(fun,idb,ide,'uni',0);

And checking the output:

>> C{:}
ans =
   2
   2
   2
   3
   3
   3
   5
   5
   5
ans =
   2
   2
   3
   3
   3
   4
   4
   4
   5
   5
   5

[johnson saldanha]

Error using horzcat

Dimensions of matrices being concatenated are not consistent.

Error in accelerationrate (line 21)

idx = [true,diff(a)~=0];

im getting this error

[Guillaume]

You're certainly not getting this error with the exact code that stephen gave. Of course, if your actual vector is a column vector instead of a row vector you either need to use vertical concatenation (i.e. use ; instead of , resulting in [true; diff(a)~=0]) or transpose your input into a row vector (i.e. [true, diff(a.')~=0]). First option is more efficient.

Answer 2

[johnson saldanha]

i did that but im not getting the desired output. im getting the decreasing values too

(5 5 5 5 3.75 3.75 3.75 3.75) im getting this in the output

[johnson saldanha]

in one or two cells im getting only the increasing but majority of them im getting the decreasing values too

[Stephen23]

@johnson saldanha: please upload some data that shows this behavior.

[johnson saldanha]

i will upload the column vector.

[johnson saldanha]

this is the output of one cell

[Stephen23]

@johnson saldanha: please upload the input data in a .mat file (not in an .xlsx file) in a new comment (not in an answer).

[johnson saldanha]

yes u can see theres a decrease from 13.75 to 12.5. i dont want the decrease here. the next set of increasing values should fall into the next cell. not the same cell

[johnson saldanha]

csv file is okay ?

[johnson saldanha]

the input

[Stephen23]

See my edited answer, it should work now. For your .xlsx data it gives this:

>> C{:}
ans =
   11.250
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   13.750
   13.750
   13.750
   13.750
   13.750
   13.750
   13.750
   13.750
   13.750
ans = 
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   12.500
   13.750
   13.750
   13.750
   13.750
   13.750
   13.750
   15.000
   15.000
   15.000
   15.000
   15.000
   15.000
   15.000
   15.000
   15.000
   15.000

And for your .csv data it gives this:

>> C{:}
ans =
   1.2500
   1.2500
   2.5000
   3.7500
   3.7500
   3.7500
   5.0000
   5.0000
   6.2500
   6.2500
   7.5000
   7.5000
   7.5000
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
ans =
   2.5000
   2.5000
   2.5000
   2.5000
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
ans =
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   3.7500
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   5.0000
   6.2500
   6.2500
   6.2500
   6.2500
   7.5000
   7.5000
   7.5000
   7.5000
   7.5000
   8.7500
   8.7500
   8.7500
   8.7500
   8.7500
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
ans =
   8.7500
  10.0000
  10.0000
  10.0000
  10.0000
  10.0000
  11.2500
  11.2500
  11.2500
  12.5000
  12.5000
  13.7500
  13.7500
  13.7500
  15.0000
  15.0000
  15.0000
  15.0000
  16.2500
  16.2500
  16.2500
  16.2500
  16.2500
  16.2500
  17.5000
  17.5000
  17.5000
  17.5000
  17.5000
  17.5000
  18.7500
  18.7500
  18.7500

[johnson saldanha]

thanks a lot. it works. and suppose i have to do the decrease they i have to change the > with < right