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2001 Nov 21
2
distances from points to line
Dear all,
I have discovered that there are many things that I used to do in my GIS
which are easily done directly in R, for example calculating interpoint
distances using geoR and pick out points inside a polygon using splancs.
I now wonder, is there a function to create a line object like a
watercourse and then calculate the distances between many points in space
and this line?
I couldn't
2008 Jan 07
1
Avoiding FOR loops
...5 1.75 0.5
5 3.75 1.75 0.5
6 4.75 1.75 0.5
7 5.75 1.75 0.5
8 6.75 1.75 0.5
9 7.75 1.75 0.5
10 -0.25 2.75 0.5
Here, X is a matrix of 3 variables in which each is of size 5 and XK are
some values that correspond to each variable. For each variable, I want to
do:
|Xi - xkj| where i = 1 to 3 and j = 1 to 10
It looks as if a double FOR loop would work, but can the apply function
work? Or some other function that is shorter than a FOR loop? Thank you, I
hope this makes sense.
Derek
--
View this message in context: http://www.nabble.com/Avoiding-FOR-loops-tp1465...
2007 Aug 29
0
a faster and shorter way to perform calculations?
This is a continuation from a previous posting of mine:
The following algorithm below is what I want to accomplish:
Z(xk) = Average(Yi, i belongs to Ik), where Ik contains all i such that for
each j, |Xi,j - xkj?? 2. Here, j = 1, 2 and i corresponds to the elements
in each X and/or xk
>data
x1 x2 y
1 1 2
2 2 6
3 3 12
Now, consider a second data frame or matrix (xk):
xk1 xk2
0.5 0.5
1.0 0.5
1.5 0.5
2.0 0.5
0.5 1
1.0 1
1.5 1
2.0 1
0.5 1.5
1.0 1.5...