2017-12-18 28 views
2

因此,我试图制作一个grobs列表,然后将它们传递到grobTree(),但我的列表项目不会作为grob通过do.call()读入。如何将grobs存储在列表中并将它们传递给grobTree()?

这里是我的代码:

library(purrr) 
library(grid) 
library(gridExtra) 
library(ggplot2) 
qplot(displ, year, data = mpg) 

title_segments <- c('Help ', 'me ', 'please', '!') 
colors <- c('red', 'orange', 'green', 'blue') 
nudge_x = 0 

grobs <- NULL 
grobs[1] <- list(gp = gpar(fontsize = 14, fontface = 'bold')) 
grobs[2] <- list(textGrob(label = title_segments[1], name = "title1", 
          x = unit(2.33 - nudge_x, "lines"), 
          y = unit(-.5, "lines"), 
          hjust = 0, vjust = 0, gp = gpar(col = colors[1]))) 

if(length(title_segments) > 1){ 
    x <- unit(2.24 - nudge_x, "lines") 
    more_grobs <- pmap(list(title_segments[-1], colors[-1], 
seq_along(title_segments)[-1]), function(segment, color, i){ 
    grob <- textGrob(label = segment, name = paste0('title', i, sep = ''), 
          x = x + grobWidth(paste0('title', i - 1, sep = '')),  
          y = unit(-.5, "lines"), 
          hjust = 0, vjust = 0, gp = gpar(col = color)) 
    }) 
} 
grobs <- c(grobs, more_grobs) 

grobs <- do.call(what = grobTree, args = grobs) ### ERROR HERE 

# Turn off clipping and draw plot 
gb <- ggplot_build(last_plot()) 
gt <- ggplot_gtable(gb) 
gt$layout$clip[gt$layout$name=="panel"] <- "off" 
gg <- arrangeGrob(gt, top = grobs, padding = unit(2.6, "line")) 
grid.newpage() 
grid.draw(gg) 

当我到了do.call()语句时发生错误,因为我的列表中的元素没有得到解读为grobs。

当我尝试这一点的代码,然后评估为真。

var <- NULL 
is.grob(var <- textGrob(label = title_segments[1], name = "title1", 
         x = unit(2.33 - nudge_x, "lines"), 
         y = unit(-.5, "lines"), 
         hjust = 0, vjust = 0, gp = gpar(col = colors[1]))) 

当我尝试这一点,它的计算结果为假

var2 <-NULL 
var2[1] <- textGrob(label = title_segments[1], name = "title1", 
         x = unit(2.33 - nudge_x, "lines"), 
         y = unit(-.5, "lines"), 
         hjust = 0, vjust = 0, gp = gpar(col = colors[1]))) 
is.grob(var2[1]) 

编辑::这就是我想要实现与PMAP功能。

grobs <- grobTree(
gp = gpar(fontsize = 14, fontface = 'bold'), 

textGrob(label = title_segments[1], name = "title1", 
     x = unit(2.33 - nudge_x, "lines"), 
     y = unit(-.5, "lines"), 
     hjust = 0, vjust = 0, gp = gpar(col = colors[1])), 

    if(length(title_segments) > 1){ 
    textGrob(label = title_segments[2], name = "title2", 
      x = grobWidth("title1") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[2])) 
    }, 

    if(length(title_segments) > 2){ 
    textGrob(label = title_segments[3], name = "title3", 
      x = grobWidth("title1") + grobWidth("title2") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[3])) 
    }, 
    if(length(title_segments) > 3){ 
    textGrob(label = title_segments[4], name = "title4", 
      x = grobWidth("title1") + grobWidth("title2") + grobWidth("title3") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[4])) 
    }, 
    if(length(title_segments) > 4){ 
    textGrob(label = title_segments[5], name = "title5", 
      x = grobWidth("title1") + grobWidth("title2") + grobWidth("title3") + grobWidth("title4") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[5])) 
    } 
) 
+0

grobs [1]显然不是grob – baptiste

+0

Grobs [1]应该是grobTree()的gp参数。这是我正在制作多色情节标题的一部分功能。我在编辑中发布了代码的unlooped版本。 –

+0

我发布了一个答案,以解决以高效方式生成unlooped代码的特定问题。 –

回答

1

让我们试着回答写下来的问题。这个问题,因为我读它去如下:

此代码:

grobs <- grobTree(
    gp = gpar(fontsize = 14, fontface = 'bold'), 

    textGrob(label = title_segments[1], name = "title1", 
      x = unit(2.33 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[1])), 

    if(length(title_segments) > 1){ 
    textGrob(label = title_segments[2], name = "title2", 
      x = grobWidth("title1") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[2])) 
    }, 

    if(length(title_segments) > 2){ 
    textGrob(label = title_segments[3], name = "title3", 
      x = grobWidth("title1") + grobWidth("title2") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[3])) 
    }, 
    if(length(title_segments) > 3){ 
    textGrob(label = title_segments[4], name = "title4", 
      x = grobWidth("title1") + grobWidth("title2") + grobWidth("title3") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[4])) 
    }, 
    if(length(title_segments) > 4){ 
    textGrob(label = title_segments[5], name = "title5", 
      x = grobWidth("title1") + grobWidth("title2") + grobWidth("title3") + grobWidth("title4") + unit(2.24 - nudge_x, "lines"), 
      y = unit(-.5, "lines"), 
      hjust = 0, vjust = 0, gp = gpar(col = colors[5])) 
    } 
) 

但是,此代码,这意味着对以前的代码的计算消遣,并不:

grobs <- NULL 
grobs[1] <- list(gp = gpar(fontsize = 14, fontface = 'bold')) 
grobs[2] <- list(textGrob(label = title_segments[1], name = "title1", 
          x = unit(2.33 - nudge_x, "lines"), 
          y = unit(-.5, "lines"), 
          hjust = 0, vjust = 0, gp = gpar(col = colors[1]))) 

if(length(title_segments) > 1){ 
    x <- unit(2.24 - nudge_x, "lines") 
    more_grobs <- pmap(list(title_segments[-1], colors[-1], 
seq_along(title_segments)[-1]), function(segment, color, i){ 
    grob <- textGrob(label = segment, name = paste0('title', i, sep = ''), 
          x = x + grobWidth(paste0('title', i - 1, sep = '')),  
          y = unit(-.5, "lines"), 
          hjust = 0, vjust = 0, gp = gpar(col = color)) 
    }) 
} 
grobs <- c(grobs, more_grobs) 

grobs <- do.call(what = grobTree, args = grobs) ### ERROR HERE 

发生了什么事?答案是,问题出在了前两行:

grobs <- NULL 
grobs[1] <- list(gp = gpar(fontsize = 14, fontface = 'bold')) 

分配grobs[1] <-消除了gp = ...命名为列表元素,因此该功能grobTree()不明白的是,第一个参数是不是一个GROB 。修复很简单。将这两行替换为:

grobs <- list(gp = gpar(fontsize = 14, fontface = 'bold')) 

现在工作正常,有点。 do.call()行不会导致错误了。但是,单词的间距仍然不正确,因为pmap()调用不会创建从第1个到第n个所有grob宽度的总和。相反,它只使用前一个grob的grob宽度。此问题最好用一个递归函数解决,我认为:

make_grobs <- function(words, colors, x, y, hjust = 0, vjust = 0, i = 0) { 
    n <- length(words) 
    colors <- rep_len(colors, n) 
    name <- paste0('title', i) 
    grob <- textGrob(label = words[1], name = name, 
        x = x, y = y, hjust = hjust, vjust = vjust, 
        gp = gpar(col = colors[1])) 
    if (n == 1) { 
    list(grob) 
    } 
    else { 
    c(list(grob), 
     make_grobs(words[-1], colors[-1], 
       x + grobWidth(grob), y, hjust, vjust, i + 1)) 
    } 
} 

通过这个函数时,整个再现的示例变为:

library(purrr) 
library(grid) 
library(gridExtra) 
library(ggplot2) 

title_segments <- c('Help ', 'me ', 'please', '!') 
colors <- c('red', 'orange', 'green', 'blue') 
nudge_x = 0 

grobs <- do.call(what = grobTree, 
       args = c(make_grobs(title_segments, colors, 
            x = unit(2.33 - nudge_x, "lines"), 
            y = unit(-.5, "lines")), 
          list(gp = gpar(fontsize = 14, fontface = 'bold')))) 

qplot(displ, year, data = mpg) 
gb <- ggplot_build(last_plot()) 
gt <- ggplot_gtable(gb) 
gt$layout$clip[gt$layout$name=="panel"] <- "off" 
gg <- arrangeGrob(gt, top = grobs, padding = unit(2.6, "line")) 
grid.newpage() 
grid.draw(gg) 

enter image description here

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