how to open st file

I want to use this database but I have some issues and I need help. The database is this:

https://physionet.org/content/slpdb/1.0.0/

I want to use this database for making an algorithm to detect the apnea from eeg signal. But I cannot find a way to open the .st files using MATLAB. I have tried using wfdb toolbox using rdann() function, but I cannot understand the information that gives me. How can I know in which part of the eeg signal I have each annotation? If I import the .st file in MATLAB, it shows me the information I want, but I don’t have in which sample or time I have each annotation so I can recognize this part in .dat file and plot it. Can you please tell me how to open properly .st file, so I can know when I have apnea(in which part of the eeg signal) or not?

Thanks in advance

Answer 1

[Anastasis]

Hi Christopher, Thank you very much! Currently I am trying to locate differences between 2 situations(apnea and healthy condition) and then with ml techniques new data can be classified according to their condition. I used MIT database from the beginning,so if you know how to help me with MIT database,that would be extremely helpful. Otherwise,I am going to use the database you suggested.But if you know how to open st files help me.

[Christopher McCausland]

Hi Anastasis,

Thats good, one thing to consider is that the number of non-apnic annotations will be far greater than the number of apnic annotations.

In terms of reading .st files these are physionet specific files. It should be possiable to re-generate these as .csv files from the physionet ATM (https://archive.physionet.org/physiobank) however this sever is down for a few days for maintenance. If you want to use this database the easiest option may be to wait until tommorrow and download the .st files as .csv for easy import to matlab.

Maintenance update here;

• Server maintenance between 15-18 July 2022 (https://archive.physionet.org/ will be unavailable)

Kind regards,

Christopher

[Anastasis]

Christopher thank you so much.I have seen that physiobank server is down for a while.So tomorrow I will convert st files to csv format and import then to matlab?Then I can see the informations I want to?(the sleep stage,the annotation of the sleep etc) Also if I have time or samples in one axis when I plot I can choose it from physiobank?

[Christopher McCausland]

Hi Anastasis,

Yep that is correct, I have just tried to get the annotations of that specific database myself and it's all working again. How are you getting on?

Giving a useable tab seperated output that looks like this, signals first, annotations in the AUX colum of the bottom image; (W for wake)

This should give you exactly what you need. Any issues, just reply to this, if you are good to go please accept my answer :)

Christopher

[Anastasis]

Hi Christopher,

Thank you very much for your reply.I used 2 different ways to find the information i want.The first one is what you have done.The second is using Lightwave.Lightwave is an online tool for that database and appears both signals and annotations.So i got all the information i wanted.Thanks again

Answer 2

[Christopher McCausland]

Hi Anastasis,

Can I ask what you are working on, I am researching a very similar topic and its always good to chat!

In terms of opening this data, being totally honest I would suggest you switch to this database (below). Its far bigger which you'll need if you want to do ML/DL, more genralised and in an easy format for matlab.

https://www.physionet.org/content/challenge-2018/1.0.0/

Kind regards,

Christopher