Step 1:
quadrant <- 1 + (X[, 1] < 0) + 2*(X[, 2] > 0)
This is not the usual labelling of the quadrants as '3' and '4' are
interchanged. If you want to be picky about it
quadrant <- ifelse(quadrant > 2, 7 - quadrant, quadrant)
Step 2:
angle <- atan2(X[,2], X[,1]) %% (2*pi) # I think this is w
On 12/31/2006 9:35 PM, Richard Rowe wrote:
> I am having problems with the 'if' syntax.
>
> I have an n x 4 matrix, X say. The first two columns hold x, y values and
> I am attempting to fill the second two columns with the quadrant in which
> the datapoint (x, y) is and with the heading angle.
