使用 ggplot2 居中 x 和 y 轴 [英] Center x and y axis with ggplot2

问题描述

有没有办法像传统的图形计算器一样获取坐标轴，标签位于 ggplot2 图的中心?我查看了文档，似乎没有那个功能，但其他绘图包不像 ggplot2 那样可以图形化定制.澄清一下，我希望从这样的事情出发:

Is there a way to get the axes, with labels in the center of a ggplot2 plot, like a traditional graphing calculator? I've looked through the docs and there doesn't seem to be that functionality, but other plotting packages are not as graphically customizable as ggplot2. To clarify, I was looking to go from something like this:

为此:

第一个图是用以下代码制作的:

The first plot is made with the following code:

dat = data.frame(x = 1, y =1)
p = ggplot(data = dat, aes(x=x, y=y)) + geom_point(size = 5)
p + xlim(-2,2) + ylim(-2,2)

第二个图是用 Mathematica 制作的.我遇到的主要问题是弄清楚如何使用标签制作轴，转到中心(我可以将主题设为空白等，没问题).似乎没有您可以编辑的主题参数以使其快速修复.

The second plot is made with Mathematica. The main problem I am having is figuring out how to make the axis, with labels, go to the center (I can make the theme blank, etc., no problem). There seems to be no theme parameter you can edit to make this a quick fix.

推荐答案

我认为这就是您要找的:

I think this is what you are looking for:

我已经构建了一个函数来做到这一点:

I have constructed a function that does just that:

theme_geometry <- function(xvals, yvals, xgeo = 0, ygeo = 0, 
                           color = "black", size = 1, 
                           xlab = "x", ylab = "y",
                           ticks = 10,
                           textsize = 3,
                           xlimit = max(abs(xvals),abs(yvals)),
                           ylimit = max(abs(yvals),abs(xvals)),
                           epsilon = max(xlimit,ylimit)/50){

  #INPUT:
  #xvals .- Values of x that will be plotted
  #yvals .- Values of y that will be plotted
  #xgeo  .- x intercept value for y axis
  #ygeo  .- y intercept value for x axis
  #color .- Default color for axis
  #size  .- Line size for axis
  #xlab  .- Label for x axis
  #ylab  .- Label for y axis
  #ticks .- Number of ticks to add to plot in each axis
  #textsize .- Size of text for ticks
  #xlimit .- Limit value for x axis 
  #ylimit .- Limit value for y axis
  #epsilon .- Parameter for small space


  #Create axis 
  xaxis <- data.frame(x_ax = c(-xlimit, xlimit), y_ax = rep(ygeo,2))
  yaxis <- data.frame(x_ax = rep(xgeo, 2), y_ax = c(-ylimit, ylimit))

  #Add axis
  theme.list <- 
  list(
    theme_void(), #Empty the current theme
    geom_line(aes(x = x_ax, y = y_ax), color = color, size = size, data = xaxis),
    geom_line(aes(x = x_ax, y = y_ax), color = color, size = size, data = yaxis),
    annotate("text", x = xlimit + 2*epsilon, y = ygeo, label = xlab, size = 2*textsize),
    annotate("text", x = xgeo, y = ylimit + 4*epsilon, label = ylab, size = 2*textsize),
    xlim(-xlimit - 7*epsilon, xlimit + 7*epsilon), #Add limits to make it square
    ylim(-ylimit - 7*epsilon, ylimit + 7*epsilon)  #Add limits to make it square
  )

  #Add ticks programatically
  ticks_x <- round(seq(-xlimit, xlimit, length.out = ticks),2)
  ticks_y <- round(seq(-ylimit, ylimit, length.out = ticks),2)

  #Add ticks of x axis
  nlist <- length(theme.list)
  for (k in 1:ticks){

    #Create data frame for ticks in x axis
    xtick <- data.frame(xt = rep(ticks_x[k], 2), 
                        yt = c(xgeo + epsilon, xgeo - epsilon))

    #Create data frame for ticks in y axis
    ytick <- data.frame(xt = c(ygeo + epsilon, ygeo - epsilon), 
                        yt = rep(ticks_y[k], 2))

    #Add ticks to geom line for x axis
    theme.list[[nlist + 4*k-3]] <- geom_line(aes(x = xt, y = yt), 
                                         data = xtick, size = size, 
                                         color = color)

    #Add labels to the x-ticks
    theme.list[[nlist + 4*k-2]] <- annotate("text", 
                                            x = ticks_x[k], 
                                            y = ygeo - 2.5*epsilon,
                                            size = textsize,
                                            label = paste(ticks_x[k]))


    #Add ticks to geom line for y axis
    theme.list[[nlist + 4*k-1]] <- geom_line(aes(x = xt, y = yt), 
                                             data = ytick, size = size, 
                                             color = color)

    #Add labels to the y-ticks
    theme.list[[nlist + 4*k]] <- annotate("text", 
                                            x = xgeo - 2.5*epsilon, 
                                            y = ticks_y[k],
                                            size = textsize,
                                            label = paste(ticks_y[k]))
  }

  #Add theme
  #theme.list[[3]] <- 
  return(theme.list)
}

作为示例，您可以运行以下代码来创建类似于上面的图像:

As an example you can run the following code to create an image similar to the one above:

simdata <- data.frame(x = rnorm(50), y = rnorm(50))

ggplot(simdata) +
  theme_geometry(simdata$x, simdata$y) +
  geom_point(aes(x = x, y = y), size = 3, color = "red") + 
  ggtitle("More geometric example")

ggsave("Example1.png", width = 10, height = 10)

这篇关于使用 ggplot2 居中 x 和 y 轴的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！