How do I display current speed and directional data with time on a feather plot?

Hi,

I am trying to use the feather plot function to display a set of data: speed (m/s), direction(degrees true), and time (yr:mm:dd:hh). Could someone please provide some insight...it would be greatly appreciated! I can't get the directional component to display correctly.

[Star Strider]

Posting the relevant parts of your code (and if you’re plotting empirical data, at least a sample of the data, preferably as a .mat file) would help.

[Christina]

Avg speed  Avg direction
0.042          232.1933333
0.016666667  236.7
0.071333333  229.4433333
0.039          261.07
0.030333333  290.1266667
0.043          349.7766667
0.024333333  47.37333333
0.073666667  285.9533333
0.027666667  133.7133333
0.036666667  265.3766667
0.017666667  54.52333333
0.055333333  127.0766667
0.051666667  315.3766667
0.041          351.36
0.011666667  187.91
0.050333333  122.06

I am trying to use the feather(u,v) function to show speed/direction as a function of time.

Answer 1

[Kelly Kearney]

The problem is likely that you're viewing it with an unequal data aspect ratio... your speeds are so small compared to the unit spacing along the x axis that when stretched to fill the axis, all angles look vertical. I'd recommend scaling the data for display:

a = [...
0.042          232.1933333
0.016666667  236.7
0.071333333  229.4433333
0.039          261.07
0.030333333  290.1266667
0.043          349.7766667
0.024333333  47.37333333
0.073666667  285.9533333
0.027666667  133.7133333
0.036666667  265.3766667
0.017666667  54.52333333
0.055333333  127.0766667
0.051666667  315.3766667
0.041          351.36
0.011666667  187.91
0.050333333  122.06];

u = a(:,1)*50 .* cosd(270 - a(:,2));
v = a(:,1)*50 .* sind(270 - a(:,2));

feather(u,v)
axis equal