Separate and store values between peaks

Hello,

I have a device that records this value "counts". The motion is similar to sinusoidal signal in that it has peaks and troughs. The device starts at a zero position and records the count value and the corresponding time in ms every time a change is detected. I am interested in the data captured between the peaks (i.e. between 2110 and 2178 below) would like the store the data points (5 in the first case), both count and time values in one matrix and then the values between 2178 and 2175 in another and so on for the complete data set but I haven't been able to make much progress with it. Appreciate any help. Thanks.

Count Time
0     0
2110  204
8     127
24    11
25	  6
24	  4
1	  160
2178  187
-9	  117
0	  17
-8	  169
2175  152

Answer 1

[Image Analyst]

Try this:

fileName = 'Count_Time Sample.xlsx'
data = readmatrix(fileName)
t = data(:, 2);
counts = data(:, 1);
plot(counts, 'b.-', 'MarkerSize', 20, 'LineWidth', 2);
hold on;
plot(t, 'r.-', 'MarkerSize', 20, 'LineWidth', 2);
grid on;

threshold = 1000;
peakIndexes = find(counts > threshold)
% Get data in between peaks
for k = 1 : length(peakIndexes) - 1
	index1 = peakIndexes(k) + 1;
	index2 = peakIndexes(k+1) - 1;
	thisData = counts(index1 : index2)
end

You'll see

data =

0 0

2110 204

8 127

24 11

25 6

24 4

1 160

2178 187

-9 117

0 17

-8 169

2175 152

83 135

119 85

3 117

2032 143

17 363

2102 157

11 136

13 48

-10 203

2152 158

-8 404

2188 143

6 147

27 45

-8 180

2162 141

peakIndexes =

2

8

12

16

18

22

24

28

thisData =

8

24

25

24

1

thisData =

-9

0

-8

thisData =

83

119

3

thisData =

17

thisData =

11

13

-10

thisData =

-8

thisData =

6

27

-8

[CH]

Thank you very much. That is pretty much exactly what I wanted. I did have two other small questions. Sorry about my limited understanding of Matlab here but is it possible to output the all 7 thisdata values in one matrix as opposed to only the last one along with the corresponding times for each position?

[Image Analyst]

Yes, but since there could be different numbers of elements, you'll have to use a cell array:

thisData{k} = counts(index1 : index2);

[CH]

Ok Perfect, thanks again. I have that working. I'll look into dealing with cell arrays

[Image Analyst]

@CH, the first item on the FAQ is about cell arrays (and for good reason):

https://matlab.fandom.com/wiki/FAQ#What_is_a_cell_array.3F

It will give you a good intuitive feel for when to use cell arrays and when you don't need to, and when to use braces, parentheses, or brackets. Admittedly, it can be very confusing but once you read the FAQ I think you'll understand much better what cell arrays are and how to use them.

[CH]

Thanks. I'll have at read