CODEWITHSUNDEEP
r
Carl Morgenstern
Carl Morgenstern

Reputation: 49

R variable usage with ~

When I look at documentation like:

plot_ly(mpg, x = ~cty, y = ~hwy, z = ~cyl) %>%
  add_markers(color = ~cyl)

I wonder what the ~ is doing. The mpg data set has variables city, etc so what is wrong with using city instead of ~city ?

When should I add ~ in front of variable names?

Upvotes: 0

Views: 22

Answers (1)

akrun
akrun

Reputation: 887571

According to ?plot_ly

A formula must always be used when referencing column name(s) in data (e.g. plot_ly(mtcars, x = ~wt)). Formulas are optional when supplying values directly, but they do help inform default axis/scale titles (e.g., plot_ly(x = mtcars$wt) vs plot_ly(x = ~mtcars$wt))

In the context of plot_ly, it is taking inputs as formula when unquoted columns are provided or can directly give the value of the column by extracting the column (mtcars$wt or mtcars[["wt"]] or mtcars[, "wt"]

Upvotes: 2

Related Questions