Add column with values to table based on value in existing column (look up)

I want to add a column to the end of Matrix.csv (my actual data is irregular and 18000+ lines) that matches the value in the Direction column to the heading below and outputs the corresponding wDir value.

I am trying to produce something like an excel lookup function after creating headingTable through the below code.

heading = ["000", "015", "030", "045", "060", "075", "090", "105", "120", "135", "150", "165", ...
    "180", "195", "210", "225", "240", "255", "270", "285", "300", "315", "330", "345"];
wDir = [90 75 60 45 30 15 0 345 330 315 300 295 270 255 240 225 210 195 180 165 150 135 120 105];
count = 0;
for i =1:numel(wDir)
    heading1 = heading(i);
    wDir1 = wDir(i);
    outData = [heading1 wDir1];
    count =count + 1;
    headingTable(count,:) = outData;
end

Answer 1

[Stephen23]

This is MATLAB so forget about Excel and loops.

Use e.g. ISMEMBER or DISCRETIZE:

T = readtable('Matrix.csv')

T = 23×4 table
    speed    Direction    Height    Period
    _____    _________    ______    ______

      6           0        7.18     13.98 
      6           0         6.7     15.21 
      6           0         7.1     15.67 
      6          15        0.96      4.94 
      6          15        1.02      6.03 
      6          60        5.86     13.57 
      6          60        6.12     14.25 
      6         255        1.91        15 
      6         330        4.14     16.32 
      6         330        5.07      5.05 
      9          90        7.16     15.52 
     12          75           2      4.98 
     12         105        2.05      7.96 
     15         105         3.1     10.91 
     15         120        2.92      7.31 
     15         120        3.06      7.83 

H = [0,15,30,45,60,75,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315,330,345,360];
W = [90,75,60,45,30,15,0,345,330,315,300,295,270,255,240,225,210,195,180,165,150,135,120,105];
T.WDir = discretize(T.Direction,H,W)

T = 23×5 table
    speed    Direction    Height    Period    WDir
    _____    _________    ______    ______    ____

      6           0        7.18     13.98      90 
      6           0         6.7     15.21      90 
      6           0         7.1     15.67      90 
      6          15        0.96      4.94      75 
      6          15        1.02      6.03      75 
      6          60        5.86     13.57      30 
      6          60        6.12     14.25      30 
      6         255        1.91        15     195 
      6         330        4.14     16.32     120 
      6         330        5.07      5.05     120 
      9          90        7.16     15.52       0 
     12          75           2      4.98      15 
     12         105        2.05      7.96     345 
     15         105         3.1     10.91     345 
     15         120        2.92      7.31     330 
     15         120        3.06      7.83     330 

Even better would be to avoid those fiddly vectors and functions entirely:

T.Wsimple = mod(90-T.Direction,360)

T = 23×6 table
    speed    Direction    Height    Period    WDir    Wsimple
    _____    _________    ______    ______    ____    _______

      6           0        7.18     13.98      90        90  
      6           0         6.7     15.21      90        90  
      6           0         7.1     15.67      90        90  
      6          15        0.96      4.94      75        75  
      6          15        1.02      6.03      75        75  
      6          60        5.86     13.57      30        30  
      6          60        6.12     14.25      30        30  
      6         255        1.91        15     195       195  
      6         330        4.14     16.32     120       120  
      6         330        5.07      5.05     120       120  
      9          90        7.16     15.52       0         0  
     12          75           2      4.98      15        15  
     12         105        2.05      7.96     345       345  
     15         105         3.1     10.91     345       345  
     15         120        2.92      7.31     330       330  
     15         120        3.06      7.83     330       330  

[Jack]

Many thanks, that solves my issues.

I have some additional columns that are sadly not as simple as your mod() suggestion and discretize works perfectly