# coord_trans

From ggplot2 v2.2.1
by Hadley Wickham

##### Transformed Cartesian coordinate system

`coord_trans`

is different to scale transformations in that it occurs after
statistical transformation and will affect the visual appearance of geoms - there is
no guarantee that straight lines will continue to be straight.

##### Usage

`coord_trans(x = "identity", y = "identity", limx = NULL, limy = NULL, xtrans, ytrans)`

##### Arguments

- x, y
- transformers for x and y axes
- limx, limy
- limits for x and y axes. (Named so for backward compatibility)
- xtrans, ytrans
- Deprecated; use
`x`

and`y`

instead.

##### Details

Transformations only work with continuous values: see
`trans_new`

for list of transformations, and instructions
on how to create your own.

##### Examples

`library(ggplot2)`

```
# See ?geom_boxplot for other examples
# Three ways of doing transformation in ggplot:
# * by transforming the data
ggplot(diamonds, aes(log10(carat), log10(price))) +
geom_point()
# * by transforming the scales
ggplot(diamonds, aes(carat, price)) +
geom_point() +
scale_x_log10() +
scale_y_log10()
# * by transforming the coordinate system:
ggplot(diamonds, aes(carat, price)) +
geom_point() +
coord_trans(x = "log10", y = "log10")
# The difference between transforming the scales and
# transforming the coordinate system is that scale
# transformation occurs BEFORE statistics, and coordinate
# transformation afterwards. Coordinate transformation also
# changes the shape of geoms:
d <- subset(diamonds, carat > 0.5)
ggplot(d, aes(carat, price)) +
geom_point() +
geom_smooth(method = "lm") +
scale_x_log10() +
scale_y_log10()
ggplot(d, aes(carat, price)) +
geom_point() +
geom_smooth(method = "lm") +
coord_trans(x = "log10", y = "log10")
# Here I used a subset of diamonds so that the smoothed line didn't
# drop below zero, which obviously causes problems on the log-transformed
# scale
# With a combination of scale and coordinate transformation, it's
# possible to do back-transformations:
ggplot(diamonds, aes(carat, price)) +
geom_point() +
geom_smooth(method = "lm") +
scale_x_log10() +
scale_y_log10() +
coord_trans(x = scales::exp_trans(10), y = scales::exp_trans(10))
# cf.
ggplot(diamonds, aes(carat, price)) +
geom_point() +
geom_smooth(method = "lm")
# Also works with discrete scales
df <- data.frame(a = abs(rnorm(26)),letters)
plot <- ggplot(df,aes(a,letters)) + geom_point()
plot + coord_trans(x = "log10")
plot + coord_trans(x = "sqrt")
```

*Documentation reproduced from package ggplot2, version 2.2.1, License: GPL-2 | file LICENSE*

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