ggmap，使用coord_cartesian将所有点推向北方 [英] ggmap, using coord_cartesian pushes all points to the north

问题描述

正如标题所说，当我将 coord_cartesian 添加到我的ggmap时，它会将我所有的点移动。这里有一些数据。

$ pre $ pricingata <-structure（list（nodename = c（CIN.WABRIVR.2，CIN。 WHEATCTG1，
CONS.ADA，CONS.ALCONA，CONS.CADILAC，CONS.CROTON，CONS.GAYLORD1，
CONS.GRATIOT1，CONS。 GRAYLGY2，CONS.GRAYLNG，CONS.HARDY，
CONS.HILLMAN，CONS.HODENPYL，CONS.HOLL，CONS.KALK，CONS.KARN1，
CONS.KENCNTY1，CONS.LANS，CONS.LUDINGTN1，CONS.MIPOWER1，
CONS.RENAIGEN1，CONS.STRAITS，CONS.TUSCOLA1， CONS.VKLINCOLN，
CONS.VKMCBAIN1，CONS.ZEELAND1A），
lat = c（39.922328,39.53,42.962672,44.561961,44.26169,43.437322,45.0306,43.433889，
43.408056,44.604921,43.486618,45.0688,44.36286,42.7925,44 .6889,43.644996，
42.949575,42.719722,43.8942,43.9375,43.1864,45.766859,43.525278,44.68,44.204,42.8067），
lon = c（-87.446358，-87.4247，-85.494071，-83.804505， -85.435224，-85.664462，-84.7039，-84.4975，-84.462222，
-84.690578，-85.629866，-83.8932，-85.819968，-86.092222，-85.2019，-83.840074，-85.693209，-84.551667，
-86.4447，-86.425，-84.8429，-84.756601，-83.65，-83.4167，-85.2206，-86.0558），
price = c（30.3,32.08,36.71,35.78,36.12,36.33,35.58,35.16,36.12 ，36.12,35.9,35.8,36.05,36.38，
35.98,23.18,36.06,34.55,34.87,34.6,34.6,38.49,34.23,35.64,35.43,36.33），
pricecut = structure（c（ 7L，8L，8L，8L，8L，8L，8L，8L，8L，8L，8L，8L，8B，8L，8L，8L，8L，8L，8L， （ - 10,0]，（0,6]，（6,14，8L， ]，（14,20），（20,26），（26,30），（30,34），
（34,38），（38 ，（42.66），（46,50），（50,56），（56,62），（62,68），
（68,76），（76,82），（82,90），（90,100），（100,115），（115,125），（125,150），$ b $ （150,200），（200,250），（250,300），（300,400），（400,500），
（500,600），（600,800）， ，1e + 03]），
class = c（ordered，factor））），.Names = c（nodename，lat，lon，price，pricecut ），row.names = 75：100，class =data.frame）


这是我的代码加上结果

  m <-get_map（location = c（lon = -89.6，lat = 41.8），zoom = 5 ）
 base< -ggmap（m，extent ='device'）
 base + geom_point（aes（x = lon，y = lat，color = pricecut） ，size = 6，alpha = .7，data = pricedata）
  

这是我期望的结果然而，当我添加 coord_cartesian 事物变得奇怪

  base + geom_point（aes（x = lon，y = lat ，color = pricecut），size = 6，alpha = .7，data = pricedata）+ coord_cartesian（xlim = c（-95，-80），ylim = c（38,50））
  

注意：我从 ggmap call so中省略了 extent ='device'你可以看到这个图中的边界是什么。

---

至于使用 coord_cartesian ，看起来像 coord_cartesian 以某种方式混淆了地图的比例。让我们从地图开始：

  ggmap（m）
  

给出：

当您使用 scale_y_continuous 切片时：

 <$ c 
 
 
 
 
 
 
 
 $（$） > 
 
 
 
你得到：
 
 
 
  
 
 
 
然而，当使用 coord_cartesian 进行类似的分片时：
  ggmap（m）+ 
 geom_blank（）+ 
 coord_cartesian（ylim = c（38,50））
  
您可以： 
 
 
  
 
 
 
正如您所看到的，地图在水平方向伸展，同时保持相同的高度。这导致地图垂直移动。当使用 scale_y_continuous 时，地图会保持正确的比例。因此，不是那些向上移动的点，而是向下移动的地图。 
As the title says when I add coord_cartesian to my ggmap it moves all of my points up.  Here's some data.
pricedata<-structure(list(nodename = c("CIN.WABRIVR.2", "CIN.WHEATCTG1", 
                                       "CONS.ADA", "CONS.ALCONA", "CONS.CADILAC", "CONS.CROTON", "CONS.GAYLORD1", 
                                       "CONS.GRATIOT1", "CONS.GRAYLGY2", "CONS.GRAYLNG", "CONS.HARDY", 
                                       "CONS.HILLMAN", "CONS.HODENPYL", "CONS.HOLL", "CONS.KALK", "CONS.KARN1", 
                                       "CONS.KENCNTY1", "CONS.LANS", "CONS.LUDINGTN1", "CONS.MIPOWER1", 
                                       "CONS.RENAIGEN1", "CONS.STRAITS", "CONS.TUSCOLA1", "CONS.VKLINCOLN", 
                                       "CONS.VKMCBAIN1", "CONS.ZEELAND1A"), 
                          lat = c(39.922328, 39.53, 42.962672, 44.561961, 44.26169, 43.437322, 45.0306, 43.433889, 
                                  43.408056, 44.604921, 43.486618, 45.0688, 44.36286, 42.7925, 44.6889, 43.644996, 
                                  42.949575, 42.719722, 43.8942, 43.9375, 43.1864, 45.766859, 43.525278, 44.68, 44.204, 42.8067), 
                          lon = c(-87.446358, -87.4247, -85.494071, -83.804505, -85.435224, -85.664462, -84.7039, -84.4975, -84.462222, 
                                  -84.690578, -85.629866, -83.8932, -85.819968, -86.092222, -85.2019, -83.840074, -85.693209, -84.551667, 
                                  -86.4447, -86.425, -84.8429, -84.756601, -83.65, -83.4167, -85.2206, -86.0558), 
                          price = c(30.3, 32.08, 36.71, 35.78, 36.12, 36.33, 35.58, 35.16, 36.12, 36.12, 35.9, 35.8, 36.05, 36.38, 
                                    35.98, 23.18, 36.06, 34.55, 34.87, 34.6, 34.6, 38.49, 34.23, 35.64, 35.43, 36.33), 
                          pricecut = structure(c(7L, 7L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 8L, 
                                                 8L, 8L, 5L, 8L, 8L, 8L, 8L, 8L, 9L, 8L, 8L, 8L, 8L), 
                         .Label = c("(-10,0]", "(0,6]", "(6,14]", "(14,20]", "(20,26]", "(26,30]", "(30,34]", 
                                    "(34,38]", "(38,42]", "(42,46]", "(46,50]", "(50,56]", "(56,62]", "(62,68]", 
                                    "(68,76]", "(76,82]", "(82,90]", "(90,100]", "(100,115]", "(115,125]", "(125,150]", 
                                    "(150,200]", "(200,250]", "(250,300]", "(300,400]", "(400,500]", 
                                    "(500,600]", "(600,800]", "(800,1e+03]"), 
                         class = c("ordered", "factor"))), .Names = c("nodename", "lat", "lon", "price", "pricecut"), row.names = 75:100, class = "data.frame")
Here's my code plus the result
m<-get_map(location=c(lon=-89.6,lat=41.8),zoom=5)
base<-ggmap(m,extent='device') 
base+geom_point(aes(x=lon,y=lat, colour=pricecut), size=6, alpha=.7, data=pricedata)


That is the result I expect

However, when I add coord_cartesian things get strange
base+geom_point(aes(x=lon,y=lat, colour=pricecut), size=6, alpha=.7, data=pricedata)+coord_cartesian(xlim=c(-95,-80), ylim=c(38,50))
解决方案
Instead of using coord_cartesian you can probably better set the limits with scale_x_continuous and scale_y_continuous as follows:
ggmap(m) +
  geom_point(aes(x=lon,y=lat, colour=pricecut), size=6, alpha=.7, data=pricedata) +
  scale_x_continuous(limits = c(-95, -80), expand = c(0, 0)) +
  scale_y_continuous(limits = c(38, 50), expand = c(0, 0))
which gives the following map:



Note: I omitted extent='device' from the ggmap call so you can see what the boundaries are in this plot.



As with regard to the effect of using coord_cartesian, it seems that coord_cartesian somehow messes with the ratios of the map. Let's start with just the map:
ggmap(m)
gives:



When you slice this map with scale_y_continuous:
ggmap(m) +
  geom_blank() +
  scale_y_continuous(limits = c(38, 50), expand = c(0, 0))
you get:



However when doing a similar slice with coord_cartesian:
ggmap(m) +
  geom_blank() +
  coord_cartesian(ylim=c(38,50))
you get:



As you can see, the map gets stretched horizontally while at the same time maintaining the same height. This causes the map to shift vertically. When using scale_y_continuous the map keeps the correct ratio. It's therefore not the points that get shifted upwards, but the map that gets shifted downwards.

                        
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