Define aesthetic mappings programmatically

Aesthetic mappings describe how variables in the data are mapped to visual properties (aesthetics) of geoms. aes() uses non-standard evaluation to capture the variable names. aes_ and aes_string require you to explicitly quote the inputs either with "" for aes_string(), or with quote or ~ for aes_(). (aes_q is an alias to aes_). This makes aes_ and aes_string easy to program with.

aes_(x, y, ...)

aes_string(x, y, ...)

aes_q(x, y, ...)

x, y, ...

List of name value pairs. Elements must be either quoted calls, strings, one-sided formulas or constants.


aes_string and aes_ are particularly useful when writing functions that create plots because you can use strings or quoted names/calls to define the aesthetic mappings, rather than having to use substitute() to generate a call to aes().

I recommend using aes_(), because creating the equivalents of aes(colour = "my colour") or aes{x = `X$1`} with aes_string() is quite clunky.

Life cycle

All these functions are soft-deprecated. Please use tidy evaluation idioms instead (see the quasiquotation section in aes() documentation).

See Also


  • aes_
  • aes_string
  • aes_q
# Three ways of generating the same aesthetics
aes(mpg, wt, col = cyl)
aes_(quote(mpg), quote(wt), col = quote(cyl))
aes_(~mpg, ~wt, col = ~cyl)
aes_string("mpg", "wt", col = "cyl")

# You can't easily mimic these calls with aes_string
aes(`$100`, colour = "smooth")
aes_(~ `$100`, colour = "smooth")
# Ok, you can, but it requires a _lot_ of quotes
aes_string("`$100`", colour = '"smooth"')

# Convert strings to names with
var <- "cyl"
aes(col = x)
aes_(col =
# }
Documentation reproduced from package ggplot2, version 3.3.0, License: GPL-2 | file LICENSE

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