向ggplot地图添加比例尺 [英] Adding scale bar to ggplot map
本文介绍了向ggplot地图添加比例尺的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在 ggplot2 中制作了这张地图：
库（maptools）; library（ggplot2）
data（wrld_simpl）
world< - fortify（wrld_simpl）
worldUk< - subset（world，id ==GBR）
ggplot +
geom_path（aes（long，lat，group = group），data = worldUk，color =black，fill = NA）+
coord_equal（）
使用photoshop，我已经在地图上添加了比例尺。如何使用 ggplot2 添加类似的比例尺？这个帖子添加了一个比例尺，但是该条不指向距离： map-ggplot2上的比例尺和北箭
解决方案
我在 http://editerna.free.fr/wp/?p=76 ，我发现它很简单，工作完美所以我必须分享吧！
很简单，首先将下面的代码粘贴到控制台中（无需编辑）
库（maptools）库（ggplot2）
库（网格）
＃然后，我们需要一个函数来获取比例bar坐标：
＃
＃结果＃
＃--------＃
＃返回一个列表，其元素为：
＃ - rectangle：包含绘制第一个矩形坐标的data.frame;
＃ - rectangle2：包含绘制第二个矩形的坐标的data.frame;
＃ - 图例：包含图例文本坐标的数据框，以及文本。
＃
＃参数：＃
＃-------------＃
＃lon，lat：左下角的经度和纬度第一个矩形画;
＃distanceLon：每个矩形的长度;
＃distanceLat：每个矩形的宽度;
＃distanceLegend：矩形和图例文字之间的距离;
＃dist.units：距离单位km（公里）（默认），nm（海里），mi（法定里程）。 createScaleBar< -
函数（lon，lat，distanceLon，distanceLat，distanceLegend，dist.units =
km）{
＃第一个矩形
bottomRight< - gcDestination lon = lon，lat = lat，bearing = 90，dist = distanceLon，dist.units = dist.units，model =WGS84）
topLeft< - gcDestination（lon = lon，lat = lat，bearing = 0，dist = distanceLat，dist.units = dist.units，model =WGS84）
rectangle < - cbind（lon = c（lon，lon，bottomRight [1，long] ，bottomRight [1，long]，lon），
lat = c（lat，topLeft [1，lat]，topLeft [1，lat]，lat，lat））
矩形< - data.frame（rectangle，stringsAsFactors = FALSE）
＃第一个矩形右侧的第二个矩形
bottomRight2 < - gcDestination（lon = lon，lat = lat， = 90，dist = distanceLon * 2，dist.units = dist.units，model =WGS84）
rectangle2 < - cbind（lon = c（bottomRight [1，long]，bottomRight [ long]，bottomRight2 [1，long]，bottomRight2 [1，lo ng]，
bottomRight [1，long]），
lat = c（lat，topLeft [1，lat]，topLeft [1，lat]，lat，lat） ）
rectangle2< - data.frame（rectangle2，stringsAsFactors = FALSE）
＃现在我们来处理文本
onTop< - gcDestination（lon = lon，lat = lat，bearing = 0，dist = distanceLegend，dist.units = dist.units，model =WGS84）
onTop2< - onTop3< - onTop
onTop2 [1，long]< ; - bottomRight [1，long]
onTop3 [1，long]< - bottomRight2 [1，long]
legend< - rbind（onTop，onTop2 ，onTop3）
legend< - data.frame（cbind（legend，text = c（0，distanceLon，distanceLon * 2）），stringsAsFactors = FALSE，row.names = NULL）
return （矩形=矩形，矩形2 =矩形2，图例=图例））}我们还需要一个函数来获取北箭头的坐标：
＃
＃结果＃
＃ --------＃
＃返回一个列表，包含：
＃ - res：坐标绘制箭头;
＃ - 箭头中间的坐标（将绘制N）。
＃
＃参数：＃
＃-------------＃
＃scaleBar：createScaleBar（）的结果;
＃长度：所需长度的箭头;
＃距离：图例矩形和箭头底部之间的距离;
＃dist.units：距离单位km（公里）（默认），nm（海里），mi（法定里程）。 createOrientationArrow< -
函数（scaleBar，length，distance = 1，dist.units =km）{
lon< - scaleBar $ rectangle2 [1,1]
lat& - scaleBar $ rectangle2 [1,2]
＃箭头的底点
begPoint< - gcDestination（lon = lon，lat = lat，bearing = 0，dist = distance，dist $。
lon< - begPoint [1，long]
lat< - begPoint [1，lat]
＃让我们创建一个端点
onTop< - gcDestination（lon = lon，lat = lat，bearing = 0，dist = length，dist.units = dist.units，model =WGS84）
leftArrow< - gcDestination（lon = onTop [1，long]，lat = onTop [1，lat]，bearing = 225，dist = length / 5，dist.units =
dist.units，model =WGS84）
rightArrow< - gcDestination（lon = onTop [1，long]，lat = onTop [1，lat]， = 135，dist = length / 5，dist.units =
dist.units，model =WGS84）
res < - rbind（
cbind（x = lon，y = lat，xend = onTop [1，long]，yend = onTop [1，lat]），
cbind（x = leftArrow [1，long y = leftArrow [1，lat]，xend = onTop [1，long]，yend = onTop [1，lat]），
cbind（x = rightArrow [1，long] ，y = rightArrow [1，lat]，xend = onTop [1，long]，yend = onTop [1，lat]））
res < - as.data 。框架（res，stringsAsFactors = FALSE）
＃将绘制N的坐标
coordsN < - cbind（x = lon，y =（lat + onTop [ lat]）/ 2）
return（list（res = res，coordsN = coordsN））}最后一个函数使用户可以绘制元素：
＃
＃结果＃
＃--------＃
＃此功能可以在ggplot对象上绘制一个比例尺，并且可以选择方向箭头＃
＃参数：＃
＃-------------＃
＃lon，lat：绘制第一个矩形左下角的经度和纬度;
＃distanceLon：每个矩形的长度;
＃distanceLat：每个矩形的宽度;
＃distanceLegend：矩形和图例文字之间的距离;
＃dist.units：距离单位km（公里）（默认），nm（海里），mi（法定里程）;
＃rec.fill，rec2.fill：填充矩形的颜色（默认为白色，黑色，分别）;
＃rec.colour，rec2.colour：矩形颜色（两者默认为黑色）;
＃legend.colour：图例颜色（默认为黑色）;
＃legend.size：图例大小（默认为3）;
＃orientation：（boolean）如果为TRUE（默认），向绘图添加方向箭头;
＃arrow.length：箭头长度（默认为500公里）;
＃arrow.distance：比例尺和箭头底部之间的距离（默认为300公里）;
＃arrow.North.size：N字母的大小（默认为6）。 scaleBar< - 函数（lon，lat，distanceLon，distanceLat，distanceLegend，
dist.unit =km，rec.fill =white，rec.colour =black，rec2.fill
=black，rec2.colour =black，legend.colour =black，legend.size = 3，orientation = TRUE，arrow.length = 500，arrow.distance = 300，arrow.North.size = 6）{
laScaleBar< - createScaleBar（lon = lon，lat = lat，distanceLon = distanceLon，distanceLat = distanceLat，distanceLegend =
distanceLegend，dist.unit = dist.unit）
＃第一个矩形
rectangle1< - geom_polygon（data = laScaleBar $ rectangle，aes（x = lon，y = lat），fill = rec.fill，color = rec.colour）
＃第二个矩形
rectangle2< - geom_polygon（data = laScaleBar $ rectangle2，aes（x = lon，y = lat），fill = rec2.fill，color = rec2.colour）
＃图例
scaleBarLegend< - annotate（text，label = paste（laScaleBar $ legend [，text]，dist.unit，sep =），x =
laScaleBar $ legend [ 长]，y = laScaleBar $ legend [，lat]，size =
legend.size，color = legend.colour）
res < - list（rectangle1，rectangle2，scaleBarLegend）
if（orientation）{＃添加一个箭头指向北
coordsArrow< - createOrientationArrow（scaleBar = laScaleBar，length = arrow.length，distance = arrow.distance，dist.unit =
dist.unit）
arrow< - list（geom_segment（data = coordsArrow $ res，aes（x = x，y = y，xend = xend，yend = yend）），annotate（text N，x =
coordsArrow $ coordsN [1，x]，y = coordsArrow $ coordsN [1，y]，size =
arrow.North.size，color =black ））
res< - c（res，arrow）
}
return（res）}
现在，绘制一张地图！
首先创建您的ggplot地图，并使用«+»符号添加比例尺作为额外的图层：
your_ggplot_object - > your_ggplot_object + scaleBar（lon = -130，lat = 26，distanceLon = 500，pre>
distanceLat = 100，distanceLegend = 200，dist.unit =km）
在上面的例子中，我调用了scaleBar函数，并为参数指定了一些值。例如，lon = -130，lat = 26表示我想要矩形的左下角在（-130,26）。您需要根据需要定义每个参数的其他值（功能标题中每个参数的描述）。
I've produced this map in
ggplot2:library(maptools); library(ggplot2) data(wrld_simpl) world <- fortify(wrld_simpl) worldUk <- subset(world, id=="GBR") ggplot() + geom_path(aes(long, lat, group=group), data=worldUk, color="black", fill=NA) + coord_equal()Using photoshop, I've added a scale bar to the map. How can I add a similar scale bar using
ggplot2? This post adds a scale bar, but the bar doesn't refer to distance: scale bar and north arrow on map-ggplot2解决方案I found this answer on http://editerna.free.fr/wp/?p=76 and I found it simple and worked perfectly so I must share it!
It is simple, first paste the code below into your console (no need for editing)
library(maps) library(maptools) library(ggplot2) library(grid) #Then, we need a function to get the scale bar coordinates: # # Result # #--------# # Return a list whose elements are : # - rectangle : a data.frame containing the coordinates to draw the first rectangle ; # - rectangle2 : a data.frame containing the coordinates to draw the second rectangle ; # - legend : a data.frame containing the coordinates of the legend texts, and the texts as well. # # Arguments : # #-------------# # lon, lat : longitude and latitude of the bottom left point of the first rectangle to draw ; # distanceLon : length of each rectangle ; # distanceLat : width of each rectangle ; # distanceLegend : distance between rectangles and legend texts ; # dist.units : units of distance "km" (kilometers) (default), "nm" (nautical miles), "mi" (statute miles). createScaleBar <- function(lon,lat,distanceLon,distanceLat,distanceLegend, dist.units = "km"){ # First rectangle bottomRight <- gcDestination(lon = lon, lat = lat, bearing = 90, dist = distanceLon, dist.units = dist.units, model = "WGS84") topLeft <- gcDestination(lon = lon, lat = lat, bearing = 0, dist = distanceLat, dist.units = dist.units, model = "WGS84") rectangle <- cbind(lon=c(lon, lon, bottomRight[1,"long"], bottomRight[1,"long"], lon), lat = c(lat, topLeft[1,"lat"], topLeft[1,"lat"],lat, lat)) rectangle <- data.frame(rectangle, stringsAsFactors = FALSE) # Second rectangle t right of the first rectangle bottomRight2 <- gcDestination(lon = lon, lat = lat, bearing = 90, dist = distanceLon*2, dist.units = dist.units, model = "WGS84") rectangle2 <- cbind(lon = c(bottomRight[1,"long"], bottomRight[1,"long"], bottomRight2[1,"long"], bottomRight2[1,"long"], bottomRight[1,"long"]), lat=c(lat, topLeft[1,"lat"], topLeft[1,"lat"], lat, lat)) rectangle2 <- data.frame(rectangle2, stringsAsFactors = FALSE) # Now let's deal with the text onTop <- gcDestination(lon = lon, lat = lat, bearing = 0, dist = distanceLegend, dist.units = dist.units, model = "WGS84") onTop2 <- onTop3 <- onTop onTop2[1,"long"] <- bottomRight[1,"long"] onTop3[1,"long"] <- bottomRight2[1,"long"] legend <- rbind(onTop, onTop2, onTop3) legend <- data.frame(cbind(legend, text = c(0, distanceLon, distanceLon*2)), stringsAsFactors = FALSE, row.names = NULL) return(list(rectangle = rectangle, rectangle2 = rectangle2, legend = legend)) } We also need a function to obtain the coordinates of the North arrow: # # Result # #--------# # Returns a list containing : # - res : coordinates to draw an arrow ; # - coordinates of the middle of the arrow (where the "N" will be plotted). # # Arguments : # #-------------# # scaleBar : result of createScaleBar() ; # length : desired length of the arrow ; # distance : distance between legend rectangles and the bottom of the arrow ; # dist.units : units of distance "km" (kilometers) (default), "nm" (nautical miles), "mi" (statute miles). createOrientationArrow <- function(scaleBar, length, distance = 1, dist.units = "km"){ lon <- scaleBar$rectangle2[1,1] lat <- scaleBar$rectangle2[1,2] # Bottom point of the arrow begPoint <- gcDestination(lon = lon, lat = lat, bearing = 0, dist = distance, dist.units = dist.units, model = "WGS84") lon <- begPoint[1,"long"] lat <- begPoint[1,"lat"] # Let us create the endpoint onTop <- gcDestination(lon = lon, lat = lat, bearing = 0, dist = length, dist.units = dist.units, model = "WGS84") leftArrow <- gcDestination(lon = onTop[1,"long"], lat = onTop[1,"lat"], bearing = 225, dist = length/5, dist.units = dist.units, model = "WGS84") rightArrow <- gcDestination(lon = onTop[1,"long"], lat = onTop[1,"lat"], bearing = 135, dist = length/5, dist.units = dist.units, model = "WGS84") res <- rbind( cbind(x = lon, y = lat, xend = onTop[1,"long"], yend = onTop[1,"lat"]), cbind(x = leftArrow[1,"long"], y = leftArrow[1,"lat"], xend = onTop[1,"long"], yend = onTop[1,"lat"]), cbind(x = rightArrow[1,"long"], y = rightArrow[1,"lat"], xend = onTop[1,"long"], yend = onTop[1,"lat"])) res <- as.data.frame(res, stringsAsFactors = FALSE) # Coordinates from which "N" will be plotted coordsN <- cbind(x = lon, y = (lat + onTop[1,"lat"])/2) return(list(res = res, coordsN = coordsN)) } The last function enables the user to draw the elements: # # Result # #--------# # This function enables to draw a scale bar on a ggplot object, and optionally an orientation arrow # # Arguments : # #-------------# # lon, lat : longitude and latitude of the bottom left point of the first rectangle to draw ; # distanceLon : length of each rectangle ; # distanceLat : width of each rectangle ; # distanceLegend : distance between rectangles and legend texts ; # dist.units : units of distance "km" (kilometers) (by default), "nm" (nautical miles), "mi" (statute miles) ; # rec.fill, rec2.fill : filling colour of the rectangles (default to white, and black, resp.); # rec.colour, rec2.colour : colour of the rectangles (default to black for both); # legend.colour : legend colour (default to black); # legend.size : legend size (default to 3); # orientation : (boolean) if TRUE (default), adds an orientation arrow to the plot ; # arrow.length : length of the arrow (default to 500 km) ; # arrow.distance : distance between the scale bar and the bottom of the arrow (default to 300 km) ; # arrow.North.size : size of the "N" letter (default to 6). scaleBar <- function(lon, lat, distanceLon, distanceLat, distanceLegend, dist.unit = "km", rec.fill = "white", rec.colour = "black", rec2.fill = "black", rec2.colour = "black", legend.colour = "black", legend.size = 3, orientation = TRUE, arrow.length = 500, arrow.distance = 300, arrow.North.size = 6){ laScaleBar <- createScaleBar(lon = lon, lat = lat, distanceLon = distanceLon, distanceLat = distanceLat, distanceLegend = distanceLegend, dist.unit = dist.unit) # First rectangle rectangle1 <- geom_polygon(data = laScaleBar$rectangle, aes(x = lon, y = lat), fill = rec.fill, colour = rec.colour) # Second rectangle rectangle2 <- geom_polygon(data = laScaleBar$rectangle2, aes(x = lon, y = lat), fill = rec2.fill, colour = rec2.colour) # Legend scaleBarLegend <- annotate("text", label = paste(laScaleBar$legend[,"text"], dist.unit, sep=""), x = laScaleBar$legend[,"long"], y = laScaleBar$legend[,"lat"], size = legend.size, colour = legend.colour) res <- list(rectangle1, rectangle2, scaleBarLegend) if(orientation){# Add an arrow pointing North coordsArrow <- createOrientationArrow(scaleBar = laScaleBar, length = arrow.length, distance = arrow.distance, dist.unit = dist.unit) arrow <- list(geom_segment(data = coordsArrow$res, aes(x = x, y = y, xend = xend, yend = yend)), annotate("text", label = "N", x = coordsArrow$coordsN[1,"x"], y = coordsArrow$coordsN[1,"y"], size = arrow.North.size, colour = "black")) res <- c(res, arrow) } return(res) }Now, to plot onto a map!
First create your ggplot map, and add the scale bar as an extra layer, using the « + » sign:
your_ggplot_object -> your_ggplot_object + scaleBar(lon = -130, lat = 26, distanceLon = 500, distanceLat = 100, distanceLegend = 200, dist.unit = "km")On the example above, I call the « scaleBar » function, and I specify some values for the arguments. For instance, lon = -130, lat = 26 means I want the bottom left point of the rectangle to be at (-130,26). You need to define the other values of each argument according to what you want (there is a description of each argument in the header of the function).
这篇关于向ggplot地图添加比例尺的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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