R ggplot2 coord_cartesian 笛卡爾坐標

coord_cartesian(
  xlim = NULL,
  ylim = NULL,
  expand = TRUE,
  default = FALSE,
  clip = "on"
)

# There are two ways of zooming the plot display: with scales or
# with coordinate systems.  They work in two rather different ways.

p <- ggplot(mtcars, aes(disp, wt)) +
  geom_point() +
  geom_smooth()
p
#> `geom_smooth()` using method = 'loess' and formula = 'y ~ x'


# Setting the limits on a scale converts all values outside the range to NA.
p + scale_x_continuous(limits = c(325, 500))
#> `geom_smooth()` using method = 'loess' and formula = 'y ~ x'
#> Warning: Removed 24 rows containing non-finite values (`stat_smooth()`).
#> Warning: Removed 24 rows containing missing values (`geom_point()`).


# Setting the limits on the coordinate system performs a visual zoom.
# The data is unchanged, and we just view a small portion of the original
# plot. Note how smooth continues past the points visible on this plot.
p + coord_cartesian(xlim = c(325, 500))
#> `geom_smooth()` using method = 'loess' and formula = 'y ~ x'


# By default, the same expansion factor is applied as when setting scale
# limits. You can set the limits precisely by setting expand = FALSE
p + coord_cartesian(xlim = c(325, 500), expand = FALSE)
#> `geom_smooth()` using method = 'loess' and formula = 'y ~ x'


# Simiarly, we can use expand = FALSE to turn off expansion with the
# default limits
p + coord_cartesian(expand = FALSE)
#> `geom_smooth()` using method = 'loess' and formula = 'y ~ x'


# You can see the same thing with this 2d histogram
d <- ggplot(diamonds, aes(carat, price)) +
  stat_bin2d(bins = 25, colour = "white")
d


# When zooming the scale, the we get 25 new bins that are the same
# size on the plot, but represent smaller regions of the data space
d + scale_x_continuous(limits = c(0, 1))
#> Warning: Removed 17502 rows containing non-finite values (`stat_bin2d()`).
#> Warning: Removed 17 rows containing missing values (`geom_tile()`).


# When zooming the coordinate system, we see a subset of original 50 bins,
# displayed bigger
d + coord_cartesian(xlim = c(0, 1))