Computing the Standard Deviation of Values in a column in Matlab

Say I have the following dataset:

I would like to compute that standard deviation using ONLY SPEED values from ONLY 15 rows at a time in the table shown. How would I go about executing this in Matlab? Is there a specific code that can simplify this task?

[Dominique Gorissen]

I am assuming that you already have this table imported into matlab? If not use the read() command to do so.

Then first convert your desired column into an array and then use std to calculate the standard deviation

SpeedArray=table2array(Table(4,:));
StandardDeviation=std(SpeedArray(1:15));

[Jana Sarran]

Thank you.

Unfortunately, this example code is not working.

In the first line of Code, I was able to extract the array values for my speed column using this code:

SpeedArray = Arraytable (:,3) %The speed data is in the third column% 

However, I was not able to find the standard deviations for every 15 row of data using the other code. I believe the standard deviation calculation would need to be repeated for every 15 rows and may be required to be coded using Loops. I am not sure.

Answer 1

[Dyuman Joshi]

out = std(tablename.Speed(1:15))

[Jana Sarran]

Thank you.

Unfortunately, this code does not provide calculations for every 15 rows.

[Dyuman Joshi]

"Unfortunately, this code does not provide calculations for every 15 rows."

I must have skipped past this, my bad.

%Assuming the total number of rows is a multiple of 15
arr = reshape(tablename.Speed,15,[]);
out = std(arr,1)

[Dyuman Joshi]

@Jana Sarran did you check my updated answer?

[Jana Sarran]

Hi @Dyuman Joshi. Thank you for your assistance. This code worked perfectly! :)

[Torsten]

Isn't a "moving standard deviation" required, i.e. standard deviation of rows 1-15, 2-16, 3-17 etc ?