Any way to extend the line in the legend?

Let us say I have the following graph plotted using ggplot:

Is there anyway to extend how much line length is开发者_开发百科 displayed in the legend? Sometimes, it just gets impossible to identify which line correspond to which line in the graph using the legend.

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here is an option legend.key.width:

# sample data frame
df <- data.frame(x = c(rnorm(100, -3), rnorm(100), rnorm(100, 3)), 
                 g = gl(3, 100))
df <- ddply(df, .(g), summarize, x = x, y = ecdf(x)(x))

ggplot(df, aes(x, y, colour = g, linetype = g)) + 
    geom_line() + 
    theme(legend.key.width = unit(10, "line"))

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opts is not working with ggplot2. You need to use theme, so instead you need to type:

+ theme(legend.key.width = unit(10, "line"))