try this
t <- TazProperties..
v <- aggregate(t$Area, by=list(t$TAZ,t$Props), sum)
names(v) <- c("TAZ", "Prop", "area")
tapply(v$area, v$Prop, function(x) v$TAZ[which.max(x)])
note that you have to deal with the cases where there is a tie for the
maximum. The above just returns the first maximum.
Nikhil
On Feb 8, 2010, at 1:14 PM, LCOG1 wrote:
Good day all,
I am having an issue coercing my data. Below i have some data on
taxlots
and an associated TAZ(transportation analsysi zone) that each
property is
within. The main issue is that some properties cross TAZ boundaries
so i
need to make a decision as to which TAZ the property belongs too, i
would
like to do this based on the area of the Property and ultimately
assign the
the property to the TAZ in which the majority or the most of the
area is
within. For instance in the data below:
Property p754921 is in two TAZs, 38 and 37. Since the property is
mostly
in 37 i would like to assign this value to the list of
properties(Props) so
that
MultiTazProperties_ goes from
$p754921
[1] 38 37 37
$p75506
[1] 171 171 282 171
$p75508
[1] 46 46 169 169 169
to....
$p754921
[1] 37
$p75506
[1] 282
$p75508
[1] 46
Props TAZ Area
1 p754921 38 109828.040
2 p754921 37 128134.710
3 p754921 37 46469.570
4 p75506 171 37160.210
5 p75506 171 40080.500
6 p75506 282 344679.660
7 p75506 171 16972.280
8 p75508 46 342309.558
9 p75508 46 260906.870
10 p75508 169 17014.659
11 p75508 169 7285.706
12 p75508 169 10936.316
#Data to use
Props<-c("p754921","p754921" ,"p754921","p75506" ,"p75506"
,"p75506","p75506"
,"p75508","p75508","p75508","p75508","p75508")
TAZ<-c(38,37,37,171,171,282,171,46,46,169,169,169)
Area<-c(109828.04, 128134.71, 46469.57, 37160.21,
40080.50,344679.66,16972.28,
342309.558, 260906.870, 17014.659, 7285.706, 10936.316)
TazProperties..<-data.frame(Props,TAZ,Area)
MultiTazProperties_<-tapply(TAZ , Props, function(x) x)
MultiTazArea_<-tapply(Area , Props, function(x) x)
Hope my inquiry is clear. Thanks
--
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