定製R在迴路內Markdown繪圖大小

Question

我在R Markdown/knittr文檔內創建條形圖。我會將圖的垂直尺寸與條形圖中的行數成比例。

編輯：最好的解決方案還可以交叉表和圖。見Interleaving tables and plots in R Markdown, within loop

在這個例子中，具有「3化油器」的汽車的MPG圖與具有「2化油器」的汽車的圖高度相同，即使對於2化油器汽車有三種不同的齒輪配置並且只有一個用於3-Carburetor汽車。

```{r cars, echo=FALSE} 
library(ggplot2) 

carb.possibilities <- sort(unique(as.character(mtcars$carb))) 

filtereds <- lapply(carb.possibilities, function(carb.ct) { 
    return(mtcars[ mtcars$carb == carb.ct , ]) 
}) 

carb.possibilities <- paste(carb.possibilities, ' Carburetors', sep = '') 

names(filtereds) <- carb.possibilities 

lapply(carb.possibilities, function(one.possibility) { 

    current.possibility <- filtereds[[one.possibility]] 

    ggplot(current.possibility, aes(factor(gear), mpg)) + 
    coord_flip() + 
    labs(x = "Gears", title = one.possibility) + 
    geom_point(position=position_jitter(width = 0.1, height = 0.1)) 
}) 
``` 

Answer 1

下面是使用grid.arrange

```{r cars, echo=FALSE, fig.height=30} 
library(ggplot2); library(gridExtra) 

carb.possibilities <- sort(unique(as.character(mtcars$carb))) 

filtereds <- lapply(carb.possibilities, function(carb.ct) { 
    return(mtcars[ mtcars$carb == carb.ct , ]) 
}) 

carb.possibilities <- paste(carb.possibilities, ' Carburetors', sep = '') 

names(filtereds) <- carb.possibilities 
p <- list() 
k <- 1 
heights <- c() 
for(one.possibility in carb.possibilities){ 
    current.possibility <- filtereds[[one.possibility]] 
    heights[k] <- length(unique(current.possibility$gear)) 
    p[[k]] <- ggplot(current.possibility, aes(factor(gear), mpg)) + 
    coord_flip() + 
    labs(x = "Gears", title = one.possibility) + 
    geom_point(position=position_jitter(width = 0.1, height = 0.1)) 
    k <- k + 1 
} 

do.call(grid.arrange, c(p, list(ncol = 1, heights= heights))) 

```