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Squish infinite values in coord_sf(), coord_map(), and coord_polar() #2972

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merged 12 commits into from
Nov 26, 2018

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yutannihilation
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@yutannihilation yutannihilation commented Oct 31, 2018

Fixes #2971 (and r-spatial/sf#879)

It seems CoordSf, CoordMap, and CoordPolar don't follow the convention of treating Inf as the edge of the range. This PR fixes it.

CoordSf

It seems CoordSf$transform() just forget to squish infinite values to range as coord_cartesian() does.

CoordMap

In CoordMap, Inf can be converted to NA by mapproj:: mapproject(). So, just applying squish_infinite() is not enough; we need to restore the Inf from the original data.

CoordPolar

For angle (theta), Inf and -Inf are squashed into 0, which is both the start and the end of the circle. For radius (r), Inf is squashed to 0.4, the hardcoded value in r_rescale(), and -Inf is squashed to 0.

Results

library(ggplot2)

ggplot(sf::st_point(c(0, 0))) +
  geom_sf() +
  annotate("text", -Inf, Inf, label = "Top-left", hjust = 0, vjust = 1)

ggplot(data.frame(x = 0, y = 0)) +
  geom_point(aes(x,y)) +
  annotate("text", -Inf, Inf, label = "Top-left", hjust = 0, vjust = 1) +
  coord_map()

ggplot(data.frame(x = "a", y = 1), aes(x, y)) +
  geom_col(fill = "white") +
  coord_polar() +
  annotate("text", Inf, Inf, label = "Top-Center") +
  annotate("text", -Inf, -Inf, label = "Center-Center")

Created on 2018-11-26 by the reprex package (v0.2.1)

@clauswilke
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This seems reasonable to me. Are there other coords that have the same issue?

@yutannihilation
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yutannihilation commented Nov 1, 2018

Thanks, here's a table of transform()s. To me,

  • CoordCartesian and CoordTrans are fine.
  • CoordFlip is fine since it uses CoordCartesian$transform() inside.
  • CoordFixed and CoordQuickmap are fine since they inherit from CoordCartesian.
  • CoordSf needs to be fixed.
  • CoordMap seems to have the same issue, so I'll fix this as well.
  • CoordPolar seems to have the same issue, but I'm yet to find what it means to "squash infinite values to range" in this coordinate system...
library(ggplot2)
library(purrr)

e <- as.environment("package:ggplot2")
coords_names <- ls(e, pattern = "^Coord")
coords <- map(set_names(coords_names), get, envir = e)

transforms <- coords %>%
  map("transform") %>%
  map(rlang::expr_text) %>%
  map(sprintf, fmt = '<div class="highlight highlight-source-r"><pre>%s</pre></div>')

knitr::kable(
  tibble::enframe(transforms),
  format = "html",
  escape = FALSE
)

name

value

Coord

function (data, range) 
NULL

CoordCartesian

function (data, panel_params) 
{
    rescale_x <- function(data) rescale(data, from = panel_params$x.range)
    rescale_y <- function(data) rescale(data, from = panel_params$y.range)
    data <- transform_position(data, rescale_x, rescale_y)
    transform_position(data, squish_infinite, squish_infinite)
}

CoordFixed

NULL

CoordFlip

function (data, panel_params) 
{
    data <- flip_labels(data)
    CoordCartesian$transform(data, panel_params)
}

CoordMap

function (self, data, panel_params) 
{
    trans <- mproject(self, data$x, data$y, panel_params$orientation)
    out <- cunion(trans[c("x", "y")], data)
    out$x <- rescale(out$x, 0:1, panel_params$x.proj)
    out$y <- rescale(out$y, 0:1, panel_params$y.proj)
    out
}

CoordPolar

function (self, data, panel_params) 
{
    data <- rename_data(self, data)
    data$r <- r_rescale(self, data$r, panel_params)
    data$theta <- theta_rescale(self, data$theta, panel_params)
    data$x <- data$r * sin(data$theta) + 0.5
    data$y <- data$r * cos(data$theta) + 0.5
    data
}

CoordQuickmap

NULL

CoordSf

function (self, data, panel_params) 
{
    data[[geom_column(data)]] <- sf_rescale01(data[[geom_column(data)]], 
        panel_params$x_range, panel_params$y_range)
    data <- transform_position(data, function(x) sf_rescale01_x(x, 
        panel_params$x_range), function(x) sf_rescale01_x(x, 
        panel_params$y_range))
    data
}

CoordTrans

function (self, data, panel_params) 
{
    trans_x <- function(data) transform_value(self$trans$x, data, 
        panel_params$x.range)
    trans_y <- function(data) transform_value(self$trans$y, data, 
        panel_params$y.range)
    new_data <- transform_position(data, trans_x, trans_y)
    warn_new_infinites(data$x, new_data$x, "x")
    warn_new_infinites(data$y, new_data$y, "y")
    transform_position(new_data, squish_infinite, squish_infinite)
}

Created on 2018-11-01 by the reprex package (v0.2.1)

@yutannihilation
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Hmm, coord_map() does have the same problem, but it seems the same fix is not enough...

library(ggplot2)

p <- ggplot(data.frame(x = 0, y = 0)) +
  geom_point(aes(x,y)) +
  annotate("text", -Inf, Inf, label = "Top-left", hjust = 0, vjust = 1)

patchwork::wrap_plots(
  p + coord_map(),
  p + coord_quickmap()
)

Created on 2018-11-01 by the reprex package (v0.2.1)

The problem is that CoordMap$transform() converts Inf to NA because underlying mapproj::mapproject() does so. But, mapproj::mapproject() originally perservers Inf. After building a plot, the same function returns different result. What happened...?

library(ggplot2)

mapproj::mapproject(data.frame(x = c(-Inf, 0, 1), y = c(0, 1, Inf)))
#> $x
#> [1] -Inf    0    1
#> 
#> $y
#> [1]   0   1 Inf

p <- ggplot(data.frame(x = 0, y = 0)) +
  geom_point(aes(x,y)) +
  annotate("text", -Inf, Inf, label = "Top-left", hjust = 0, vjust = 1) +
  coord_map()

b <- ggplot_build(p)

mapproj::mapproject(data.frame(x = c(-Inf, 0, 1), y = c(0, 1, Inf)))
#> $x
#> [1] NA  0 NA
#> 
#> $y
#> [1]         NA 0.01745418         NA
#> 
#> $range
#> [1] 0.00000000 0.00000000 0.01745418 0.01745418
#> 
#> $error
#> [1] 1

Created on 2018-11-01 by the reprex package (v0.2.1)

@yutannihilation
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Maybe mapproj::.Last.projection() matters? Anyway, we need some tweaks to restore NAs to Infs...

@yutannihilation yutannihilation changed the title Let coord_sf() to squish infinite values to range Squish infinite values in coord_sf(), coord_map(), and coord_polar() Nov 19, 2018
@yutannihilation
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This also needs to wait for #3003.

@yutannihilation
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Ah, sorry, I forgot to add a NEWS bullete... Will add one and merge.

@yutannihilation yutannihilation merged commit 23a23cd into tidyverse:master Nov 26, 2018
@yutannihilation yutannihilation deleted the fix-coord-sf-inf branch November 26, 2018 23:40
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Unable to add text annotation to geom_sf plot
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