Calculating value from two column with a cell string

Hi,

I have three columns like this way. here a is cell string, 2nd and 3rd column are numbers

• 1st column: a,a,a....
• 2nd column:102, 135.....and 3rd column:103,136.......
• a 102 103
• a 135 136
• a 157 160
• b 189 191
• b 201 202
• a 222 223
• a 245 250
• b 290 292

I want to write a formula, which show the total duration of seconds of a and b.

For example: here total duration of a is = (160-102) + (250-222) = 86 seconds.

Please suggest me how to do it.

Thanks

[Guillaume]

It would make more sense to me (and easier to code) if duration of a was either:

1. 250-102
2. 103-102 + 136-135 + 160-157 + 223-222 + 250-245

Answer 1

[Guillaume]

Assuming that the string is a single letter and your cell array is defined like this:

c={'a' 102 103
   'a' 135 136
   'a' 157 160
   'b' 189 191
   'b' 201 202
   'a' 222 223
   'a' 245 250
   'b' 290 292}

Then the following will do what you want:

starts = find(diff([' ' c{:, 1} ' '])) %starts of intervals + end of last interval
cconcat = [c(starts(1:end-1), [1 2]), c(starts(2:end)-1, 3)] %intervals concatenated
durations = vertcat(cconcat{:, 3}) - vertcat(cconcat{:, 2}) %duration of intervals
[names, ~, idnames] = unique([cconcat{:, 1}]')
fulldurations = [num2cell(names) num2cell(accumarray(idnames, durations))]