I have two sets of coordinates and I need to calculate the distance between them in longitude converted to meters. The departure() function serves this purpose well. However, it returns all positive values for distance regardless of which coordinate is more east/west than the other. Is there a way I can get directionality from this function, or by altering the output in some indexed way?
lat1=[45.73366;42.30074;42.11033;37.69088];
lon1=[-115.85149;-115.54721;-108.03860;-96.52568];
lat2=[45.94414;41.20918;42.64974;36.66341];
lon2=[-115.28569;-116.87984;-108.61347;-95.06520];
coords=table(lat1,lon1,lat2,lon2)
coords =
lat1 lon1 lat2 lon2
______ _______ ______ _______
45.734 -115.85 45.944 -115.29
42.301 -115.55 41.209 -116.88
42.11 -108.04 42.65 -108.61
37.691 -96.526 36.663 -95.065
coords.lon_diff_m=departure(coords.lon1,coords.lon2,(coords.lat1+coords.lat2)./2,wgs84Ellipsoid,'degrees')
coords =
lat1 lon1 lat2 lon2 lon_diff_m
______ _______ ______ _______ __________
45.734 -115.85 45.944 -115.29 43956
42.301 -115.55 41.209 -116.88 1.1083e+05
42.11 -108.04 42.65 -108.61 47344
37.691 -96.526 36.663 -95.065 1.297e+05
As you can see, all the distances are positive values. I would like the output to be directional where, if coordinate 1 is west of coordinate 2 the output is negative, and if coordinate 1 is east of coordinate 2 the output is positive.
I suppose I could use an index vector of lat1<lat2 to multiply the rows that qualify by -1.
idx=(coords.lon1<coords.lon2);
coords.lon_diff_m(idx)=coords.lon_diff_m(idx).*-1
coords =
lat1 lon1 lat2 lon2 lon_diff_m
______ _______ ______ _______ __________
45.734 -115.85 45.944 -115.29 -43956
42.301 -115.55 41.209 -116.88 1.1083e+05
42.11 -108.04 42.65 -108.61 47344
37.691 -96.526 36.663 -95.065 -1.297e+05
I came up with this answer as I am writing this question. However, if anybody has a better way to do this or sees an error in my method, please let me know.
