Skip to contents

Add regression to plotly plot

Source: R/plotly_Utils.R
add_smooth.Rd

[Stable]

Modifies an existing plot to include a regression line with confidence interval.

Usage

add_smooth(
  p = plotly::last_plot(),
  x = NULL,
  y = NULL,
  data = NULL,
  method = "lm",
  line = T,
  ci = 0.95,
  stats
)

Arguments

p

The plot to which the shape should be added. Default is the plotly::last_plot().

x

X value for regression if not the original x value of the plot. Be sure to specify as a formula, e.g. x = ~pred.

y

Y value for regression if not the original y value of the plot. Be sure to specify as a formula, e.g. y = ~obs.

data

A secondary data object to use for regression other than the original plot data.

method

The tegression method, currently either "lm" (the default) for linear regression, or "loess" for loess regression.

line

Controls characteristics of lines. This argument maps to plotly line attributes. TRUE will plot default lines. FALSE will suppress lines. If a list, can control many line characteristics, including overriding defaults. Use the plotly plotly::schema() command in the console and navigate to traces > scatter > attributes > line to see all the ways the line can be formatted. Most common will be:

  • color Line color.

  • dash Plotting character. See plotly::schema(), traces > scatter > attributes > line > dash > values.

  • width Thickness in points.

Example: line = list(color = "red", dash = "longdash", width = 2) Default is list(color = "blue", width = 2). The confidence interval will have the same color but at opacity 0.2.

ci

Confidence interval for regressions. Default is 0.95. It can be suppressed by setting to 0.

stats

Add the statistics from linear regression to the plot. Ignored if method = "loess". If missing or FALSE, will be suppressed. Can be set to TRUE which results in default format of list(x= 0.8, y = 0.1, bold = F, font = list(color = "black", family = "Arial", size = 14)). The coordinates are relative to the plot with lower left = (0,0), upper right = (1,1). This argument maps to plotly::add_text(). It is also an option that can be set in setPMoptions to avoid specifying this argument for every plot. The default option is TRUE. If specified as a Pmetrics option, it can be overridden for specific plots by supplying a value.

Details

This function adds a regression line to an existing plotly plot. The default is to use the x and y values in the plot, but this can be overridden by specifying a data object. If another data object is used, values for x and y must also be specified. Alternatively, the original data can be used and new columns selected for regression by omitting the data argument and specifying new x and y values. The intent of this function is to replicate the behavior of ggplot::geom_smooth().

See also

add_shapes

Examples

plotly::plot_ly(mtcars,
  x = ~hp, y = ~mpg,
  type = "scatter", mode = "markers", showlegend = FALSE
) %>%
  add_smooth()


plotly::plot_ly(iris,
  x = ~Sepal.Length, y = ~Petal.Length,
  type = "scatter", mode = "markers", showlegend = FALSE
) %>%
  add_smooth(method = "loess", ci = 0.9, line = list(color = "red", dash = "dash"))