ggplot with bty="n"，或者如何将网格坐标添加到绘图坐标

Question

我有一个关于 this one. Basically I want to add bty = "n" to a ggplot2 graph in a proper way. Emphasis on proper here because the solution in the other question almost what I want, except for this detail: 的问题，我希望轴线能一直持续到刻度结束，而不是直到它的中间。首先，图表代码：

library(ggplot2)
library(grid)

graph = ggplot(faithful, aes(x=eruptions, y=waiting)) +
   geom_point(shape=21) +
    theme(
    # tick width, a bit exaggerated as example
    axis.ticks = element_line(size = 5, color = "gray") 
    )
graph # graph with no axis lines

# get axis limits
gb = ggplot_build(graph)
xLim = range(gb$layout$panel_ranges[[1]]$x.major_source)
yLim = range(gb$layout$panel_ranges[[1]]$y.major_source)

# add lines
graph +
    geom_segment(y = -Inf, yend = -Inf, x = xLim[1], xend = xLim[2]) +
    geom_segment(x = -Inf, xend = -Inf, y = yLim[1], yend = yLim[2])

所以问题是：我在 x 轴上绘制从 50 到 90。但是，刻度线以 50 和 90 为中心，因此它们每边延伸 size = 5 的一半。 ?element_line 告诉我线条/边框大小默认以毫米为单位。因此，我想画一条从 50 - 5mm / 2 到 90 + 5mm / 2 的线。我尝试了以下（许多变体）：

xLim = range(gb$layout$panel_ranges[[1]]$x.major_source)
yLim = range(gb$layout$panel_ranges[[1]]$y.major_source)

uType = "npc"
uType2 = "mm" 

# attempt conversion of units
xLim[1] = xLim[1] - convertWidth(unit(2.5, units = uType2),
                      unitTo = uType, valueOnly = TRUE)
xLim[2] = xLim[2] +  convertWidth(unit(2.5, units = uType2),
                      unitTo = uType, valueOnly = TRUE)

yLim[1] = yLim[1] - convertHeight(unit(2.5, units = uType2),
                             unitTo = uType, valueOnly = TRUE)
yLim[2] = yLim[2] - convertHeight(unit(2.5, units = uType2),
                             unitTo = uType, valueOnly = TRUE)

# redraw graph    
cairo_pdf("Rplot.pdf")
graph +
    geom_segment(y = -Inf, yend = -Inf, x = xLim[1], xend = xLim[2]) +
    geom_segment(x = -Inf, xend = -Inf, y = yLim[1], yend = yLim[2])
dev.off()

但没有任何运气。有什么想法吗？

Answer 1

我相信您必须编写一个 drawDetails 方法或类似方法来在绘图时进行单位计算，这样才能起作用。

或者（也许更容易），您可以编写一个自定义的刻度 grob，它可以延伸以覆盖轴线。

（请注意，由于其 z 顺序 IIRC，两个轴具有不同的线宽；我认为该错误已修复）。

library(ggplot2)
library(grid)


element_grob.element_custom_x <- function (element, x = 0:1, y = 0:1, colour = NULL, size = NULL, 
                                           linetype = NULL, lineend = "butt", default.units = "npc", id.lengths = NULL, 
                                           ...) 
{
  gp <- gpar(lwd = ggplot2:::len0_null(size * .pt), col = colour, lty = linetype, 
             lineend = lineend)
  element_gp <- gpar(lwd = ggplot2:::len0_null(element$size * .pt), col = element$colour, 
                     lty = element$linetype, lineend = element$lineend)
  arrow <- if (is.logical(element$arrow) && !element$arrow) {
    NULL
  }
  else {
    element$arrow
  }
  g1 <- polylineGrob(x, y, default.units = default.units, 
                     gp = utils::modifyList(element_gp, gp), 
                     id.lengths = id.lengths, arrow = arrow, ...)

  vertical <- length(unique(element$x)) == 1 && length(unique(element$y)) >= 1

  g2 <- grid::editGrob(g1, y=y + unit(1,"mm"), gp=utils::modifyList(gp, list(col="green")), name="new")

  grid::grobTree(g2, g1)

}


element_grob.element_custom_y <- function (element, x = 0:1, y = 0:1, colour = NULL, size = NULL, 
                                           linetype = NULL, lineend = "butt", default.units = "npc", id.lengths = NULL, 
                                           ...) 
{
  gp <- gpar(lwd = ggplot2:::len0_null(size * .pt), col = colour, lty = linetype, 
             lineend = lineend)
  element_gp <- gpar(lwd = ggplot2:::len0_null(element$size * .pt), col = element$colour, 
                     lty = element$linetype, lineend = element$lineend)
  arrow <- if (is.logical(element$arrow) && !element$arrow) {
    NULL
  }
  else {
    element$arrow
  }
  g1 <- polylineGrob(x, y, default.units = default.units, 
                     gp = utils::modifyList(element_gp, gp), 
                     id.lengths = id.lengths, arrow = arrow, ...)

  g2 <- grid::editGrob(g1, x=x + unit(1,"mm"), gp=utils::modifyList(gp, list(col="green")), name="new")

  grid::grobTree(g2, g1)

}


## silly wrapper to fool ggplot2
x_custom <- function(...){
  structure(
    list(...), # this ... information is not used, btw
    class = c("element_custom_x","element_blank", "element") # inheritance test workaround
  ) 

}
y_custom <- function(...){
  structure(
    list(...), # this ... information is not used, btw
    class = c("element_custom_y","element_blank", "element") # inheritance test workaround
  ) 

}

graph = ggplot(faithful, aes(x=eruptions, y=waiting)) +
  geom_point(shape=21) + theme_minimal() +
  theme(
    axis.ticks.x = x_custom(size = 5, colour = "red") ,
    axis.ticks.y = y_custom(size = 5, colour = "red") ,
    axis.ticks.length = unit(2,"mm")
  )
graph # graph with no axis lines
gb <- ggplot_build(graph)
xLim = range(gb$layout$panel_ranges[[1]]$x.major_source)
yLim = range(gb$layout$panel_ranges[[1]]$y.major_source)


graph +
  geom_segment(y = -Inf, yend = -Inf, x = xLim[1], xend = xLim[2],lwd=2) +
  geom_segment(x = -Inf, xend = -Inf, y = yLim[1], yend = yLim[2],lwd=2)

Answer 2

现在简单多了：使用包 ggthemes() 中的 geom_rangeframe()。我认为它完全符合您的要求。

ggplot with bty="n"，或者如何将网格坐标添加到绘图坐标

ggplot with bty="n", or how to add grid coordinates to plot coordinates

r

ggplot2

r-grid