Finding Time Intervals with corresponding data

I have a set of data vs. time. For simplicity, let's say at I have data recorded anywhere between once per second and 4 or 5 times per second, and each time has a corresponding value of either 1, or 0. I discard all of the entries with a value 0. How can I easily tell how much time has passed with a value of 1, and what the intervals of the time is where the corresponding value is 1. Thank you.

[dpb]

Well, unless there's something unsaid, you can't. All you've told us is there's some indicator variable but nothing about what that might indicate (if anything) re: actual clock time and you've implied that the sample rate isn't fixed hence just how many intervals it's been between is also no actual information.

[RobB]

To make it more clear...1 means the switch is on, 0 means the switch is off. For the time values, I have exact values, but the sample rate can range between .8 seconds and 1.2 seconds, so not exactly every 1 second. Does that help at all? If I could find the beginning value and ending value of each time interval the switch is on (value of 1) I could just find the difference.

Answer 1

[dpb]

_"1 means the switch is on, 0 means the switch is off. ... If I could find the beginning value and ending value of each time interval the switch is on..."

istart=find([0 diff(s)]==1);  % Switch 'on' from 'off' locations
iend=find([0 diff(s)]==-1);  % Switch 'off' from 'on'

s is you switch indicator variable; use whatever variable/column you have for it...

[RobB]

When I use what you've suggested I get the error:

Error using horzcat

Dimensions of matrices being concatenated are not consistent.

For s, I am using VariableName(:,2) since the 1's and 0's are in the second column of the specific variable I'm looking at.

[Star Strider]

I’m responding here rather than to your Comment to my previous Answer.

That’s because dpb assumes your vector is a row vector. For your column vector, change the vector in the find argument to:

[0; diff(s)]

Note the semicolon (;). It will do a vertical concatenation rather than a horizontal concatenation (that uses either a comma (,) or a space delimiter).

[dpb]

Ah, yeah, I probably should've presumed it would be a column...