How to add time from 2 arrays

Hi, I am a new user of Matlab. I have the following problem:

I have two columns like this way.

• a =102 sec
• a =135
• a =157
• b =189
• b =201
• a =222
• a =245
• b =290

Here the values are in seconds. 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 = (157-102) + (245-222) = 78 seconds.

Please suggest me how to do it.

Thanks

[José-Luis]

What does

 a  102 a  135 a  157 b  189 b  201 a  222 a  245 b  290

mean?

[SS]

• a =102 sec
• a =135
• a =157
• b =189
• b =201
• a =222
• a =245
• b =290

[José-Luis]

I still don't see the two columns.

[SS]

its actually two columns..I just put an = between them.Here, a is in one column and 102 in other coloumn

[José-Luis]

So is your variable a table or do you have two column vectors: one with strings and the other with numbers?

[SS]

It's two column vectors: one with string and other with number.

Answer 1

[Andrei Bobrov]

C = {'a' 102
'a' 135
'a' 157
'b' 189
'b' 201
'a' 222
'a' 245
'b' 290}

cn = [C{:,2}]';
[~,~,c1] = unique(C(:,1));
t = [true;diff(c1)~=0];
s1 = accumarray(cumsum(t),cn,[],@(x)x(end)-x(1));

out = accumarray(c1(t),s1);

Answer 2

[Rainer]

I don't see the two columns and I don't understand what a and b are.

[SS]

sorry..i corrected it:

• a =102 sec
• a =135
• a =157
• b =189
• b =201
• a =222
• a =245
• b =290