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Add a native Office trendline to chart series

Source: R/chart_trendline.R
chart_trendline.Rd

Adds a native 'Microsoft Office' trendline (regression / fit line) to one or more series of a bar, line or scatter chart. The trendline is computed and rendered by the host application (PowerPoint, Word or Excel), so it remains editable and updates when the underlying data changes.

This exposes the native c:trendline chart element and supports linear, polynomial, exponential, logarithmic, power and moving-average fits, optional forecasting, a fixed intercept, and display of the fit equation and R-squared value.

Usage

chart_trendline(
  x,
  series = NULL,
  type = c("linear", "poly", "exp", "log", "power", "movingAvg"),
  order = 2,
  period = 2,
  forward = 0,
  backward = 0,
  intercept = NULL,
  display_equation = FALSE,
  display_r_squared = FALSE,
  name = NULL,
  line = NULL
)

Arguments

x

an ms_chart object created with ms_barchart(), ms_linechart() or ms_scatterchart().

series

character vector of series names the trendline should be added to. When NULL (default), the trendline is added to every series.

type

the trendline type, one of "linear", "poly", "exp", "log", "power" or "movingAvg".

order

polynomial order, an integer between 2 and 6. Only used when type = "poly".

period

moving-average period, an integer of at least 2. Only used when type = "movingAvg".

forward

number of periods (units) to forecast forward. Not used when type = "movingAvg".

backward

number of periods (units) to forecast backward. Not used when type = "movingAvg".

intercept

optional numeric value forcing the trendline to cross the y axis at a fixed point. Only valid for "linear", "poly" and "exp" trendlines. Use NULL (default) to let Office compute it.

display_equation

if TRUE, display the fit equation on the chart. Not available for moving-average trendlines.

display_r_squared

if TRUE, display the R-squared value on the chart. Not available for moving-average trendlines.

name

optional label for the trendline shown in the legend. When NULL, Office generates a default name.

line

an officer::fp_border() describing the trendline colour, width and dash style. When NULL, Office uses its default styling.

Value

An updated ms_chart object.

See also

ms_scatterchart(), ms_linechart(), ms_barchart()

Examples

library(officer)

dat <- data.frame(
  x = 1:20,
  y = 2 * (1:20) + rnorm(20, sd = 3)
)

sc <- ms_scatterchart(data = dat, x = "x", y = "y")
sc <- chart_trendline(
  sc,
  type = "linear",
  display_equation = TRUE,
  display_r_squared = TRUE
)