if else在ggplot中添加一个额外的图层

Question

说我想在ggplot中绘制两个图层，一个包含点，另一个包含线条，如果满足某个条件。

没有标准的代码可能如下所示：

library("ggplot2")

# Summarise number of movie ratings by year of movie
mry <- do.call(rbind, by(movies, round(movies$rating), function(df) {
  nums <- tapply(df$length, df$year, length)
  data.frame(rating=round(df$rating[1]), year = as.numeric(names(nums)), number=as.vector(nums))
}))

p <- ggplot(mry, aes(x=year, y=number, group=rating))

p + 
geom_point()+
geom_line()

现在绘制点而不仅仅是线条的条件是，一个名为tmp.data的对象不等于表达式＆＃34;没有值＆＃34;。

tmp.data<-c(1,2,3) # in this case the condition is fulfilled

# attempt to plot the two layers including the condition in the plotting function
p+ 
  if(tmp.data[1]!="no value"){ geom_point()+}
  geom_line()

...失败

Error: unexpected '}' in:
"p+ 
if(tmp.data[1]!="no value"){ geom_point()+}"

  

geom_line（）   geom_line：
  stat_identity：
  position_identity :( width = NULL，height = NULL）

Answer 1

这是使用ggplot2 2.1.0完成的。我认为你可以完成OP所希望的，只需切换括号，使它们包含整个if语句。

以下是根据Swtich是T还是F来添加水平线的示例。首先，条件为TRUE

library(ggplot2)

df<-data.frame(x=1:10,y=11:20)
Switch=T

ggplot(df,aes(x,y))+
{if(Switch)geom_hline(yintercept=15)}+
  geom_point()

现在，同样的事情，但条件是FALSE

df<-data.frame(x=1:10,y=11:20)
Switch=F

ggplot(df,aes(x,y))+
{if(Switch)geom_hline(yintercept=15)}+
  geom_point()

Answer 2

您看到的是语法错误。我能想到的最强大的方法是：

tmp.data<-c(1,2,3) 
if(tmp.data[1]!="no value") {
   p = p + geom_point()
}
p + geom_line()

所以你在序列中组合对象p，只在if语句产生geom_point()时添加TRUE。

Answer 3

在ggplot2 book之后，您可以创建一个返回列表的函数。任何NULL组件都将被忽略。

a =[31,41,59,26,41,58]
input = input("Enter number : ")
for i in range(1,len(a),1) :
    if input == a[i] :
       print(i)

library(ggplot2)
library(ggplot2movies)

# Summarise number of movie ratings by year of movie
mry <- do.call(rbind, by(movies, round(movies$rating), function(df) {
    nums <- tapply(df$length, df$year, length)
    data.frame(rating=round(df$rating[1]), year = as.numeric(names(nums)), number=as.vector(nums))
}))

# create function to add points conditionally
# If the list contains any NULL elements, they’re ignored. 
my_plot <- function(point = FALSE){
    list(
        geom_line(),
        if (point) 
            geom_point()
    )

}

p <- ggplot(mry, aes(x=year, y=number, group=rating))
p + my_plot()

^{由reprex package（v0.3.0）于2020-02-25创建}

Answer 4

library(ggplot2)

# Summarise number of movie ratings by year of movie
mry <- do.call(rbind, by(movies, round(movies$rating), function(df) {
  nums <- tapply(df$length, df$year, length)
  data.frame(rating=round(df$rating[1]), year = as.numeric(names(nums)), number=as.vector(nums))
}))

tmp.data<-c(1,2,3) # in this case the condition is fulfilled

p <- ggplot(mry, aes(x=year, y=number, group=rating))

# this won't "loop through" the data points but it's what you asked for
if (tmp.data[1]!="no value") {
  p <- p + geom_point() + geom_line()
} else {
  p <- p + geom_line()
}
p

但也许这更像你真正想要的？

mry$rating <- factor(mry$rating)
p <- ggplot(mry, aes(x=year, y=number, group=rating))
p <- p + geom_line()
p <- p + geom_point(data=mry[!(mry$rating %in% tmp.data),], 
                    aes(x=year, y=number, group=rating, color=rating), size=2)
p <- p + scale_color_brewer()
p