[R] Converting nested "for" loops to an "apply" function(s)
Kurt Newman
km_newman at hotmail.com
Sun Aug 10 00:25:47 CEST 2008
Hello,
I would like to know more about how to use the "apply" family and have attempted to convert nested "for" loops in example code from Contributed Documentation ("The Friendly Beginners' R Course” by Toby Marthews (ZIP, 2007-03-01)") to an "apply" function(s). The relevant code is:
distances=c(51,65,175,196,197,125,10,56) #distances of 8 houses from the town centre in m
bearings=c(10,8,210,25,74,128,235,335) #bearings of the houses in degrees
xpos=distances*sin(bearings*pi/180) #in sin and cos the argument MUST be in radians
ypos=distances*cos(bearings*pi/180)
numpoints=length(distances)
nnd=rep(sqrt(2*400*400),times=numpoints) #start with the maximum possible distance
for (i in 1:numpoints) {
for (j in 1:numpoints) {
if (i!=j) {
diffx=abs(xpos[i]-xpos[j])
diffy=abs(ypos[i]-ypos[j])
nd=sqrt((diffx^2)+(diffy^2))
if (nd
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