Exercise in grImport
Last week I used grImport for the first time. I decided to try perform another exercise using it. The task was to add voivodeship division of Poland.
Standard R maps do not contain such a division. I have found it on r-forge in package mapoland based on ESRI shape files, but I wanted to import such a map from SVG file which can be found onWikipedia. As last time SVG file has to be converted do PS first. Here is a comparison of both maps showing that the import worked quite well.
And this is the code I have used:
library (grImport )
PostScriptTrace ( “Wojewodztwa.ps” )
voiv <- readPicture ( “Wojewodztwa.ps.xml” )
broken.voiv <- explodePaths (voiv )
#extracting voivodeship ‘PictureStrokes’
xpath <- ypath <- list ()
sel <- c ( 2, 4, 6, 8, 20, 22, 24, 28, 30, 32, 34, 36, 38, 41, 44, 46 )
for (i in seq (along = sel )) {
xpath **\[\[**i **\]\] <-** broken.voiv **\[\[**sel **\[**i **\]\]\]**@paths **$**path@xypath **\[\[**i **\]\] <-** broken.voiv **\[\[**sel **\[**i **\]\]\]**@paths **$**path@y
}
#adding Wolin island to zachodniopomorskie
xpath [[ 2 ]] <- c (broken.voiv [ 10 ]@paths $path@x [ c ( 39 : 1, 95 : 40 )],
xpath **\[\[** 2 **\]\])**
ypath [[ 2 ]] <- c (broken.voiv [ 10 ]@paths $path@y [ c ( 39 : 1, 95 : 40 )],
ypath **\[\[** 2 **\]\])**
library (mapoland )
pl <- getShape ( “voiv” )
#functions rescaling paths to mapoland map size
transx <- function(x ) {
old **<-** c **(** min **(** sapply **(**xpath, min **))**, max **(** sapply **(**xpath, max **)))**new **<-** pl@bbox **\[** 1, **\]****((**x **–** old **\[** 1 **\]) / (**old **\[** 2 **\] – **old **\[** 1 **\])) \* (**new **\[** 2 **\] –**new **\[** 1 **\])**
+ new [ 1 ]
}
transy <- function(y ) {
old **<-** c **(** min **(** sapply **(**ypath, min **))**, max **(** sapply **(**ypath, max **)))**new **<-** pl@bbox **\[** 2, **\]****((**y **–** old **\[** 1 **\]) / (**old **\[** 2 **\] – **old **\[** 1 **\])) \* (**new **\[** 2 **\] –**new **\[** 1 **\])**
+ new [ 1 ]
}
plot (pl, lwd = 4 )
for (i in seq (along = sel )) {
lines **(**transx **(**xpath **\[\[**i **\]\])**, transy **(**ypath **\[\[**i **\]\])**, col **=** “red” **)**
}
╰+哭是因爲堅強的太久メ
小鱼儿
红太狼
港控/mmm°
谁借莪１个温暖的怀抱￠
小灰灰
系统管理员
我就是我
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