R - 如何在網格圖形對象上「縮放」

Question

我想知道是否可以「縮放」在使用網格圖形制作的繪圖/表格上？

例如，我創建了一個繪圖，但想要專注於左下角四分之一，因此可以通過將繪圖範圍設置爲x = c（0,0.5）和y = c（0,0.5）進行放大。

下面的代碼是我可以做的最好的工作，但它不能說明固定大小的元素，例如ggplot中的邊距面板。您會注意到，如果將縮放比例更改爲xrange = c(0,0.1) & yrange = c(0,0.1) ggplot保留區面板保持完全相同的大小，並將ggplot點與我疊加的grid.text元素對齊。

library(ggplot2) 
library(dplyr) 
library(grid) 


PLOT <- ggplot(iris , aes(x = Sepal.Width , y = Sepal.Length)) + geom_point() 
GPLOT <- ggplotGrob(PLOT) 

COORDS <- expand.grid(c(0:10) , c(0:10)) %>% 
    as_data_frame() %>% 
    setNames(c("x" , "y")) %>% 
    mutate(label = paste0(x , "," ,y)) %>% 
    mutate(x= x/10 , y = y/10) 


xrange <- c(0, 0.5) 
yrange <- c(0, 0.5) 

grid.newpage() 
pushViewport(
    viewport(
     x = 0.5 + (0.5 - mean(xrange))/diff(xrange) , 
     y = 0.5 + (0.5 - mean(yrange))/diff(yrange), 
     width = 1/diff(xrange) , 
     height = 1/diff(yrange) 
    ) 
) 

grid.draw(GPLOT) 
grid.text(label = COORDS$label , x = COORDS$x , y = COORDS$y) 

Answer 1

在圖表面板上只覆蓋grid.text元素是否可以？如果是這樣，這樣的事情可能會起作用。

PLOT <- ggplot(iris , aes(x = Sepal.Width , y = Sepal.Length)) + geom_point() 
GPLOT <- ggplotGrob(PLOT) 

COORDS <- expand.grid(c(0:10) , c(0:10)) %>% 
    as_data_frame() %>% 
    setNames(c("x" , "y")) %>% 
    mutate(label = paste0(x , "," ,y)) %>% 
    mutate(x= x/10 , y = y/10) 


xrange <- c(0, .5) 
yrange <- c(0, .5) 



grid.newpage() 

# Draw the labels on the plot panel 
GPLOT$layout$clip = "off" # so that labels on the boundary get drawn 
grid.draw(GPLOT) 
downViewport("panel.6-4-6-4") # The panel viewport - current.vpTree() 
grid.text(label = COORDS$label , x = COORDS$x , y = COORDS$y) 

grab = grid.grab() # Grab that plot 

# Then proceed as before - zoom into this plot 
grid.newpage() 
pushViewport(
    vp = viewport(
     x = 0.5 + (0.5 - mean(xrange))/diff(xrange) , 
     y = 0.5 + (0.5 - mean(yrange))/diff(yrange), 
     width = 1/diff(xrange) , 
     height = 1/diff(yrange), name = "Size" 
    ) 
) 

grid.draw(grab)