How to calculate the difference between different values in a table?

Hi,

I'm trying to calculate the time differences/lag between event 'ENDSACC' and '1002' (in the message), using the time of each ENDSACC to subtract the time of each 1002.

For example：For the first '1002', its time lag : 'ENDSACC'(2) (72-942= -870) 'ENDSACC'(3) (356-942= -586) 'ENDSACC'(6) (1032-942= 90).

Only the number is important so the ideal result would be like；

-870 -586 90 ...

How can I do such calculation, thanks for any help.

Answer 1

[Vilém Frynta]

% loading data and separating useful data from useless data
load Foveal.mat
T = ans; % your table
T_1002 = T(matches(T.message,'1002'),:)        % table with only "1002"

T_1002 = 5×5 table
    message      time      code    reltime        pvel    
    ________    _______    ____    _______    ____________

    {'1002'}    3137559    100       942      {0×0 double}
    {'1002'}    3139829    100      3212      {0×0 double}
    {'1002'}    3142111    100      5494      {0×0 double}
    {'1002'}    3143193    100      6576      {0×0 double}
    {'1002'}    3144087    100      7470      {0×0 double}

T_ENDSACC = T(matches(T.message,'ENDSACC'),:)  % table with only "ENDSACC"

T_ENDSACC = 57×5 table
      message       time      code    reltime        pvel    
    ___________    _______    ____    _______    ____________

    {'ENDSACC'}    3136689    400        72      {[192.9000]}
    {'ENDSACC'}    3136973    400       356      {[248.9000]}
    {'ENDSACC'}    3137198    400       581      {[130.4000]}
    {'ENDSACC'}    3137395    400       778      {[248.6000]}
    {'ENDSACC'}    3137649    400      1032      {[203.8000]}
    {'ENDSACC'}    3137896    400      1279      {[184.2000]}
    {'ENDSACC'}    3138104    400      1487      {[205.6000]}
    {'ENDSACC'}    3138730    400      2113      {[231.9000]}
    {'ENDSACC'}    3138912    400      2295      {[ 99.5000]}
    {'ENDSACC'}    3139395    400      2778      {[ 88.4000]}
    {'ENDSACC'}    3140091    400      3474      {[     287]}
    {'ENDSACC'}    3140354    400      3737      {[142.3000]}
    {'ENDSACC'}    3140683    400      4066      {[ 74.6000]}
    {'ENDSACC'}    3141321    400      4704      {[276.4000]}
    {'ENDSACC'}    3141617    400      5000      {[123.2000]}
    {'ENDSACC'}    3142048    400      5431      {[121.3000]}

% creating matrix before for loop
[x1 ~] = size(T_1002);
[x2 ~] = size(T_ENDSACC);  
T_diff = zeros(x1,x2); % will create 5x57 matrix

% doing the calculations and saving them into 5x57 matrix
for q = 1:x1
    T_diff(q,:) = int32(T_1002.reltime(q)) - int32(T_ENDSACC.reltime(:));
end

% first row is first1002 vs. endsacc times, second row is second 1002 vs. endsacc times, ...
T_diff

T_diff = 5×57

870 586 361 164 -90 -337 -545 -1171 -1353 -1836 -2532 -2795 -3124 -3762 -4058 -4489 -4788 -5006 -5183 -5366 -5727 -5805 -5899 -6218 -6441 -6706 -6896 -7235 -7468 -9158 3140 2856 2631 2434 2180 1933 1725 1099 917 434 -262 -525 -854 -1492 -1788 -2219 -2518 -2736 -2913 -3096 -3457 -3535 -3629 -3948 -4171 -4436 -4626 -4965 -5198 -6888 5422 5138 4913 4716 4462 4215 4007 3381 3199 2716 2020 1757 1428 790 494 63 -236 -454 -631 -814 -1175 -1253 -1347 -1666 -1889 -2154 -2344 -2683 -2916 -4606 6504 6220 5995 5798 5544 5297 5089 4463 4281 3798 3102 2839 2510 1872 1576 1145 846 628 451 268 -93 -171 -265 -584 -807 -1072 -1262 -1601 -1834 -3524 7398 7114 6889 6692 6438 6191 5983 5357 5175 4692 3996 3733 3404 2766 2470 2039 1740 1522 1345 1162 801 723 629 310 87 -178 -368 -707 -940 -2630

[JCH]

Thank you so much! This is beautiful. But why are the negative values show as 0, could I keep the negative values as well?

[Vilém Frynta]

Oh, I do not know. Maybe switch T_1002.reltime and T_ENDSACC.reltime in the for loop. I will take a closer look tommorow. Glad I could help.

[JCH]

Thank you!

[Vilém Frynta]

I had a bit of time and I found the fix.

New version of the for loop should work:

for q = 1:x1
    T_diff(q,:) = int32(T_1002.reltime(q)) - int32(T_ENDSACC.reltime(:));
end