Manipulation of data for plotting

When opening raw data obtained from github I found it to be of a 4D structure. So basically, the dataset that I am using being s9.mat is of size 12 x 8 x 1114 x 15:

[Number of targets, Number of channels, Number of sampling points, Number of trials] = size(eeg)

From the github site it is being told that the stimulation was shown at the 39th sample so I need to ignore the first 38 samples when processing, reducing the data to 12 x 8 x 1076 x 15. I also need to consider only the first 10 trials so I will be working on a dataset of size 3 x 8 x 1076 x 10. I require to process this data (filtering etc) however to do so I first have to extract from the dataset a 1 x 1076 vector, which represents one trial (corresponding to a stimulus frequency of 9.25Hz, recorded at one of the 8 channels) and then I can apply my filter to this vector of data.

So my problem is how I can obtain the 1 x 1076 vector so that I could proceed with further processing. Would appreciate if anyone can guide me as to how I can obtain this vector.

Answer 1

[Cris LaPierre]

Not sure how you went from 12 to 3 in your first dimension, but use indexing to reduce your data down to 12 x 8 1076 x 10.

newVar = origData(:,:,39:end,1:10)

To extract a single stimulation from a single target and a single channel for a single trial, you could do this.

% 1076 points from target 1, channel 2, trial 3
singleStim = origData(1,2,39:end,3)

To make it 1x1076, you might need to enclose everything in the function squeeze

singleStim = squeeze(origData(1,2,39:end,1))

[Rudy Steel]

It works thank you however, I obtained the data as 1076x1 do you know as to why that occurs?

[Cris LaPierre]

This is because squeeze removes all the singleton dimensions, which leaves you with 1076. It keeps that as the first dimension and adds the "x1" since it has to have a second dimension.

You just need to transpose the result using an apostrophe.

a = [1;2;3;4;5]

a = 5×1

1 2 3 4 5

b = a'

b = 1×5

1 2 3 4 5

●