Deleting rows until a certain point

I made a script that calculate some data and then plots it. I now want it to delete all the data up until a certain point. So to be more specific i want it to find the first 5 rows which values is greater that a certain value and then i want it to delete all data before that point and if possible i want it to delete the same amount of rows in another variable. I thought about using find(X>1,5) but i dont know how to mark that point and delete everything before that.

I have attached an image of the graph with a point that marks the beginning. Up until that point i want all data deleted.

Answer 1

[Jos (10584)]

Perhaps this example can help you:

% some data
t = 1:15 ;
v = [0 0 0 0 1 2 4 8 4 2 0 -2 -4 -8 -4]
% find the point
i0 = find(abs(v) > 0,1,'first')

% selection
t2 = t(i0:end)
v2 = v(i0:end) 

% show result
plot(t,v,'bo:',t2,v2,'r.-')

[Christian von Spreckelsen]

Thanks, this was really helpfull! :)

Answer 2

[Ahmet Cecen]

You can find the point by something along the lines of (you also pay attention to the dimensions of vectors, I didn't):

 datacheck = sign(data - threshold);     % find all points bigger
 highpass = conv([ones(1,5) zeros(4,1)],datacheck);   % sum previous 5 points for all points
 pointindex = find(highpass==5,1);       % find the first point with a sum 5

Then you can erase all points earlier by simply:

 data(1:pointindex)=[];