r - ggplot : Subset a layer where data is passed using a pipe

Question

我正在尝试对将数据传递到 ggplot 的绘图层进行子集化通过管道。

这是一个例子:

library(dplyr)
library(ggplot2)
library(scales)

set.seed(12345)
df_example = data_frame(Month = rep(seq.Date(as.Date("2015-01-01"),
                                             as.Date("2015-12-31"), by = "month"), 2),
                        Value = sample(seq.int(30, 150), size = 24, replace = TRUE),
                        Indicator = as.factor(rep(c(1, 2), each = 12)))

df_example %>% 
  group_by(Month) %>% 
  mutate(`Relative Value` = Value/sum(Value)) %>% 
  ungroup() %>% 
  ggplot(aes(x = Month, y = Value, fill = Indicator, group = Indicator)) + 
  geom_bar(position = "fill", stat = "identity") + 
  theme_bw()+ 
  scale_y_continuous(labels = percent_format()) + 
  geom_line(aes(x = Month, y = `Relative Value`))

这给出:

我只想出现其中一行，如果类似的东西在 geom_line 中工作，我就能够做到这一点层:

  geom_line(subset = .(Indicator == 1), aes(x = Month, y = `Relative Value`))

编辑:

session 信息:

R version 3.2.1 (2015-06-18) Platform: x86_64-w64-mingw32/x64 (64-bit) Running under: Windows Server 2012 x64 (build 9200)

locale: 2 LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252 [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C [5] LC_TIME=English_United States.1252

attached base packages: 2 stats graphics grDevices utils
datasets methods base

other attached packages: 2 scales_0.3.0 lubridate_1.3.3 ggplot2_1.0.1 lazyeval_0.1.10 dplyr_0.4.3 RSQLite_1.0.0
readr_0.2.2 [8] RJDBC_0.2-5 DBI_0.3.1 rJava_0.9-7

loaded via a namespace (and not attached): 2 Rcpp_0.12.2
knitr_1.11 magrittr_1.5 MASS_7.3-40 munsell_0.4.2
lattice_0.20-31 [7] colorspace_1.2-6 R6_2.1.1 stringr_1.0.0 plyr_1.8.3 tools_3.2.1 parallel_3.2.1 [13] grid_3.2.1
gtable_0.1.2 htmltools_0.2.6 yaml_2.1.13 assertthat_0.1
digest_0.6.8 [19] reshape2_1.4.1 memoise_0.2.1
rmarkdown_0.8.1 labeling_0.3 stringi_1.0-1 zoo_1.7-12
[25] proto_0.3-10

Answer 1

tl;dr:将数据作为函数传递到该图层，该函数根据您的条件对绘图数据进行子集化。

<小时/>

根据ggplots documentation on layers ，将数据传递到新层时有 3 个选项:

1. If NULL, the default, the data is inherited from the plot data as specified in the call to ggplot().
2. A data.frame, or other object, will override the plot data. All objects will be fortified to produce a data frame. See fortify() for which variables will be created.
3. A function will be called with a single argument, the plot data. The return value must be a data.frame, and will be used as the layer data.

前两个选项是最常用的，但当数据通过 pyps 修改后，第三个选项非常适合我们的需求。

在您的示例中，将 data = function(x) subset(x,Indicator == 1) 添加到 geom_line 即可实现以下目的:

library(dplyr)
library(ggplot2)
library(scales)

set.seed(12345)
df_example = data_frame(Month = rep(seq.Date(as.Date("2015-01-01"),
                                             as.Date("2015-12-31"), by = "month"), 2),
                        Value = sample(seq.int(30, 150), size = 24, replace = TRUE),
                        Indicator = as.factor(rep(c(1, 2), each = 12)))

df_example %>% 
  group_by(Month) %>% 
  mutate(`Relative Value` = Value/sum(Value)) %>% 
  ungroup() %>% 
  ggplot(aes(x = Month, y = Value, fill = Indicator, group = Indicator)) + 
  geom_bar(position = "fill", stat = "identity") + 
  theme_bw()+ 
  scale_y_continuous(labels = percent_format()) + 
  geom_line(data = function(x) subset(x,Indicator == 1), aes(x = Month, y = `Relative Value`))

This is the resulting plot