我有两个邮政编码列表(在R中)...其中一个儿童地址及其学业成绩和一个学校...
我希望能够为每个孩子找到最近的学校...所以大概是通过转换为长期和纬度值来计算邮政编码之间的距离吗?
然后我希望能够在谷歌地图上绘制每所学校的所有孩子...并看看住在离学校较近的孩子是否能获得更好的成绩......或许可以为孩子们设置不同颜色的学校,和孩子们根据他们的分数有颜色渐变?
也许是使用googleVis包的东西?
所以例如......
如果我们有3个孩子和2所学校的数据......
student.data <- cbind(post.codes=c("KA12 6QE", "SW1A 0AA", "WC1X 9NT"),score=c(23,58,88))
school.postcodes <- c("SL4 6DW", "SW13 9JT")
(N.B。我的实际数据显然明显大于给定的数据,因此可扩展性很有用......)
googleVis或任何其他软件包应该怎么做才能完成上述工作?
答案 0 :(得分:7)
我会从这样开始得到lat / long
为每个邮政编码获取lat / long
library(XML)
school.postcodes <- c("KA12 6QE", "SW1A 0AA", "WC1X 9NT")
ll <- lapply(school.postcodes,
function(str){
u <- paste('http://maps.google.com/maps/api/geocode/xml?sensor=false&address=',str)
doc <- xmlTreeParse(u, useInternal=TRUE)
lat=xpathApply(doc,'/GeocodeResponse/result/geometry/location/lat',xmlValue)[[1]]
lng=xpathApply(doc,'/GeocodeResponse/result/geometry/location/lng',xmlValue)[[1]]
c(code = str,lat = lat, lng = lng)
})
# get long/lat for the students
ll.students <- lapply(student.data$post.codes,
function(str){
u <- paste('http://maps.google.com/maps/api/geocode/xml?sensor=false&address=',str)
doc <- xmlTreeParse(u, useInternal=TRUE)
lat=xpathApply(doc,'/GeocodeResponse/result/geometry/location/lat',xmlValue)[[1]]
lng=xpathApply(doc,'/GeocodeResponse/result/geometry/location/lng',xmlValue)[[1]]
c(code = str,lat = lat, lng = lng)
})
ll <- do.call(rbind,ll)
ll.students <- do.call(rbind,ll.students)
do.call(rbind,ll)
code lat lng
[1,] "KA12%206QE" "55.6188429" "-4.6766226"
[2,] "SW1A%200AA" "51.5004864" "-0.1254664"
[3,] "WC1X%209NT" "51.5287992" "-0.1181098"
获取距离矩阵
library(RJSONIO)
dist.list <- lapply(seq(nrow(ll)),
function(id){
url <- paste("http://maps.googleapis.com/maps/api/distancematrix/json?origins=",
ll[id,2],",",ll[id,3],
"&destinations=",
paste( ll.students[,2],ll.students[,3],sep=',',collapse='|'),
"&sensor=false",sep ='')
res <- fromJSON(url)
hh <- sapply(res$rows[[1]]$elements,function(dest){
c(distance= as.numeric(dest$distance$value),
duration = dest$duration$text)
})
hh <- rbind(hh,destination = ll.students[,1])
})
names(dist.list) <- ll[,1]
dist.list
$`SL4 6DW`
[,1] [,2] [,3]
distance "664698" "36583" "41967"
duration "6 hours 30 mins" "43 mins" "49 mins"
destination "1" "2" "3"
$`SW13 9JT`
[,1] [,2] [,3]
distance "682210" "9476" "13125"
duration "6 hours 39 mins" "22 mins" "27 mins"
destination "1" "2" "3"