Remove decreasing data in matrix

I have a 2 column matrix with several thousand rows. In one column of the matrix, the data cyclicly increases and decreases. I want to remove all rows where the data is decreasing.

For example if my matrix looked like this:

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

I'd want to remove rows 6-9.

Can anyone help?

Answer 1

[Matt J]

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

rawdata(  [false; diff(rawdata(:,1))<0]   ,  : )=[]

rawdata = 9×2

1 2 2 2 3 2 4 2 5 2 2 2 3 2 4 2 5 2

[Emily Heil]

thank you!