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我正在制作 cholorpleth（我在这里开始的一个学习项目）。我曾经问过关于在 SO上的地图（ HERE ）上绘制文本的问题。我现在正试图在同一张地图上绘制名称，但它是多面的，但不断出现错误：

Error in eval(expr, envir, enclos) : object 'group' not found

我认为 R 讨厌我而且我是个白痴 :) traceback大约有 5 英里长，所以这也无济于事。如果你拿出geom_text 一切运行良好。

PS我知道新的geom_map并且一直在玩它，但这是一个困扰我的单独问题。

预先感谢您的帮助。

#Load three data sets from my dropbox 
load(url("http://dl.dropbox.com/u/61803503/Names/cholo.RData"))

#view head of the three data frames
lapply(list("map.data2"=map.data2, "ny"=ny, "centroids"=centroids), head)
####################################################################
# map.data2 contains the filling information (test scores)         #
# ny contains the lat and long information for plotting boundaries #
# centroids contains the information for plotting labels           #
####################################################################

#Load Necessary Libraries
library(ggplot2); library(maps); library(RColorBrewer); library(scales)

ggplot(map.data2, aes(long, lat, group=group)) +  #plot pass rates math
   geom_polygon(aes(fill=level), colour=alpha('white', 1/2), size=0.2) +
   geom_polygon(data=ny, colour='black', fill=NA) + 
   scale_fill_brewer(palette='RdYlBu', guide = guide_legend(title = 
       "Percent Passing"))+
   facet_grid(.~Subject)+
   #annotate(data = "text", label = centroids$subregion, x = centroids$long, 
   #    y = centroids$lat, size = 2, colour = "black") +
   geom_text(data=centroids, aes(x=long, y=lat, 
       label=subregions, angle=angle), size=3) +
   opts(title = "
       New York State Counties Passing Rate \non Elementary ELA Assessments") +
   opts(axis.text.x = theme_blank(), axis.text.y = theme_blank(), 
       axis.ticks = theme_blank())+
   opts(legend.background = theme_rect()) +
   scale_x_continuous('') + scale_y_continuous('') + 
   labs(title = "legend title") + theme_bw()+
   opts(axis.line=theme_blank(),axis.text.x=theme_blank(),
        axis.text.y=theme_blank(),axis.ticks=theme_blank(),
        axis.title.x=theme_blank(), legend.position="bottom",
        axis.title.y=theme_blank(),
        panel.background=theme_blank(),panel.grid.major=theme_blank(),
        panel.grid.minor=theme_blank(),plot.background=theme_blank())
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1 回答 1

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在第一次ggplot()通话中，您将 group 映射到group. 然后将此映射传递到每一层，因此 ggplot 在您的层group中使用的centroids数据中找不到时会抱怨。geom_text

groups=NULL在调用中取消映射它geom_text，这很好：

ggplot(map.data2, aes(long, lat, group=group)) +  
   geom_polygon(aes(fill=level), colour=alpha('white', 1/2), size=0.2) +
   geom_polygon(data=ny, colour='black', fill=NA) + 
   scale_fill_brewer(palette='RdYlBu', guide = guide_legend(title = 
         "Percent Passing"))+
   facet_grid(.~Subject)+
   geom_text(data=centroids, aes(x=long, y=lat, 
     label=subregion, angle=angle, group=NULL), size=3) +   # THIS HAS CHANGED!
   opts(title = " 
     New York State Counties Passing Rate \non Elementary ELA Assessments") +
   opts(axis.text.x = theme_blank(), axis.text.y = theme_blank(), 
       axis.ticks = theme_blank())+
   opts(legend.background = theme_rect()) +
   scale_x_continuous('') + scale_y_continuous('') + 
   labs(title = "legend title") + theme_bw()+
    opts(axis.line=theme_blank(),axis.text.x=theme_blank(),
      axis.text.y=theme_blank(),axis.ticks=theme_blank(),
      axis.title.x=theme_blank(), legend.position="bottom",
      axis.title.y=theme_blank(),
      panel.background=theme_blank(),panel.grid.major=theme_blank(),
      panel.grid.minor=theme_blank(),plot.background=theme_blank())
于 2012-04-19T17:48:01.373 回答