geom_path() connects the observations in the order in which they appear
in the data.
geom_line() connects them in order of the variable on the
geom_step() creates a stairstep plot, highlighting exactly
when changes occur. The
group aesthetic determines which cases are
geom_path(mapping = NULL, data = NULL, stat = "identity", position = "identity", ..., lineend = "butt", linejoin = "round", linemitre = 1, arrow = NULL, na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)geom_line(mapping = NULL, data = NULL, stat = "identity", position = "identity", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE, ...)geom_step(mapping = NULL, data = NULL, stat = "identity", position = "identity", direction = "hv", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE, ...)
- Set of aesthetic mappings created by
aes_. If specified and
inherit.aes = TRUE(the default), it is combined with the default mapping at the top level of the plot. You must supply
mappingif there is no plot mapping.
- The data to be displayed in this layer. There are three
NULL, the default, the data is inherited from the plot data as specified in the call to
data.frame, or other object, will override the plot data. All objects will be fortified to produce a data frame. See
fortifyfor which variables will be created.
functionwill be called with a single argument, the plot data. The return value must be a
data.frame., and will be used as the layer data.
- The statistical transformation to use on the data for this layer, as a string.
- Position adjustment, either as a string, or the result of a call to a position adjustment function.
- other arguments passed on to
layer. These are often aesthetics, used to set an aesthetic to a fixed value, like
color = "red"or
size = 3. They may also be parameters to the paired geom/stat.
- Line end style (round, butt, square)
- Line join style (round, mitre, bevel)
- Line mitre limit (number greater than 1)
- Arrow specification, as created by
FALSE, the default, missing values are removed with a warning. If
TRUE, missing values are silently removed.
- logical. Should this layer be included in the legends?
NA, the default, includes if any aesthetics are mapped.
FALSEnever includes, and
FALSE, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g.
- direction of stairs: 'vh' for vertical then horizontal, or 'hv' for horizontal then vertical
An alternative parameterisation is
geom_segment: each line
corresponds to a single case which provides the start and end coordinates.
# geom_line() is suitable for time series ggplot(economics, aes(date, unemploy)) + geom_line() ggplot(economics_long, aes(date, value01, colour = variable)) + geom_line() # geom_step() is useful when you want to highlight exactly when # the y value chanes recent <- economics[economics$date > as.Date("2013-01-01"), ] ggplot(recent, aes(date, unemploy)) + geom_line() ggplot(recent, aes(date, unemploy)) + geom_step() # geom_path lets you explore how two variables are related over time, # e.g. unemployment and personal savings rate m <- ggplot(economics, aes(unemploy/pop, psavert)) m + geom_path() m + geom_path(aes(colour = as.numeric(date))) # Changing parameters ---------------------------------------------- ggplot(economics, aes(date, unemploy)) + geom_line(colour = "red") # Use the arrow parameter to add an arrow to the line # See ?arrow for more details c <- ggplot(economics, aes(x = date, y = pop)) c + geom_line(arrow = arrow()) c + geom_line( arrow = arrow(angle = 15, ends = "both", type = "closed") ) # Control line join parameters df <- data.frame(x = 1:3, y = c(4, 1, 9)) base <- ggplot(df, aes(x, y)) base + geom_path(size = 10) base + geom_path(size = 10, lineend = "round") base + geom_path(size = 10, linejoin = "mitre", lineend = "butt") # NAs break the line. Use na.rm = T to suppress the warning message df <- data.frame( x = 1:5, y1 = c(1, 2, 3, 4, NA), y2 = c(NA, 2, 3, 4, 5), y3 = c(1, 2, NA, 4, 5) ) ggplot(df, aes(x, y1)) + geom_point() + geom_line() ggplot(df, aes(x, y2)) + geom_point() + geom_line() ggplot(df, aes(x, y3)) + geom_point() + geom_line() # Setting line type vs colour/size # Line type needs to be applied to a line as a whole, so it can # not be used with colour or size that vary across a line x <- seq(0.01, .99, length.out = 100) df <- data.frame( x = rep(x, 2), y = c(qlogis(x), 2 * qlogis(x)), group = rep(c("a","b"), each = 100) ) p <- ggplot(df, aes(x=x, y=y, group=group)) # These work p + geom_line(linetype = 2) p + geom_line(aes(colour = group), linetype = 2) p + geom_line(aes(colour = x)) # But this doesn't should_stop(p + geom_line(aes(colour = x), linetype=2))