Find max values within a defined range for each column and rows of a matrix

Hi!

I have a 20x305471 matrix, representing 20 variables in a time series sampled at 28.28 Hz. I have also have a time vector (1x305471) = [0, 0.0354, …. And up to 10800];

I want to extract maximum values using different time ranges. E.g. I want to find the maximum values from 0 to 40 min, 40 to 120min.. up to 160 to 180min.

Any help is very appreciated! Thanks

Answer 1

[dpb]

Turn into a timetable and use retime

[dpb]

Curious...how was performance for that size data table?

[Askeladden2]

Elapsed time is 1.852013 seconds.

For converting array to timetable, using retime and converting back to array.

Thank you for the tip.

[dpb]

Why the conversion to/from array and back again -- just read in as timetable and use it for everything...

[Askeladden2]

I need to convert them back into an array because I am using the values for creating probability distributions and etc.

[dpb]

Just reference the desired variables directly from the table/timetable -- no need to create separate, duplicates as arrays.

See the section on the table data class on how to reference into a table for the myriad of available addressing syntaxes. To return just a variable, the "dot" notation is painless and efficient...

ttMyTT=table2timetable(readtable('myfile.ext'));
plot(ttMyTT.time,ttMyTT.VarX)

No auxiliary arrays in sight/needed...use your own variable names in the data file, of course.