How to get a complete vector of breaks from the scale of a plot in R?-CodePudding

I am trying to add captions outside the plots using the solutions from this

After the caption:

The idea is that I want to avoid having to set up the y parameter every time I change the data. Imagine that that the y-axis is different (it is something like this: 0.0000, 0.0005, 0.0010, 0.0015). In that case, the appropriate y would be -0.0005 because the "jump" is 0.0005, so I just have to make it negative.

For that reason, I was wondering if it is possible to get the COMPLETE vector of values from the y-axis. For example, if we want to get all the values/breaks of the y-axis from the previous images would be: c(0.0, 0.2, 0.4, 0.6).

Does anyone know if I can get ALL the values from the y-axis of a plot?

Thanks in advance

CodePudding user response：

You can get the y axis breaks from the p object like this:

as.numeric(na.omit(layer_scales(p)$y$break_positions()))
#> [1] 0.0 0.2 0.4 0.6

However, if you want the labels to be a fixed distance below the panel regardless of the y axis scale, it would be best to use a fixed fraction of the entire panel range rather than the breaks:

yrange <- layer_scales(p)$y$range$range
ypos <- min(yrange) - 0.2 * diff(yrange)

p   coord_cartesian(clip = "off", 
                    ylim = layer_scales(p)$y$range$range, 
                    xlim = layer_scales(p)$x$range$range)  
  geom_text(data = caption_df,
            aes(y = ypos, label = c(levels(data$Sex))))

For example, suppose you had a y scale that was twice the size:

p <- data %>% 
  ggplot(aes(value))  
  geom_density(lwd = 1.2, colour="red", show.legend = FALSE)  
  geom_histogram(aes(y= 2 * ..density.., fill = id), bins=10, col="black", alpha=0.2)  
  facet_grid(id ~ Sex )  
  xlab("type_data")   
  ylab("Density")  
  ggtitle("title")  
  guides(fill=guide_legend(title="legend_title"))  
  theme(strip.text.y = element_blank())

Then the exact same code would give you the exact same label placement, without any reference to breaks:

yrange <- layer_scales(p)$y$range$range
ypos <- min(yrange) - 0.2 * diff(yrange)

p   coord_cartesian(clip = "off", 
                    ylim = layer_scales(p)$y$range$range, 
                    xlim = layer_scales(p)$x$range$range)  
  geom_text(data = caption_df,
            aes(y = ypos, label = c(levels(data$Sex))))