R图例未在图中显示

Question

I have the following R code for a simple plot:

ExperimentDataNames = c('Count', 'HumanData', 'ActualPrices')
ExperimentData <- read_csv("/Users/justin_chudley/desktop/ExperimentData.csv", col_names = ExperimentDataNames)

x <- Count <- ExperimentData$Count
y <- HumanData <- ExperimentData$HumanData
y1 <- ActualPrices <- ExperimentData$ActualPrices

plot(x,y, type = "l", xlab="Trial Number",ylab="$USD",main="Dow Jones Price vs Human Experiment")
lines(x,y1, type = "l", col=2)
legend=c('Human Data', 'Actual Prices') 

The legend does not show at all in this plot for some reason:

Why is my legend not showing?

Answer 1

With your coding, you have assigned a vector of characters to an object named legend .

In order to add a legend, you need to use the legend() function.

legend(x = 10, y = 4e5, 
       col = c("black", "red"), lty = 1, lwd = 1,
       legend = c('Human Data', 'Actual Prices'))

You can use a heuristic approach by varying the values in x and y until you find a position you like. Alternatively, you can also set x to one of several predefined values:

legend(x = "top",
       col = c("black", "red"), lty = 1, lwd = 1,
       legend = c('Human Data', 'Actual Prices'))

Other options are to set x to "bottomright", "bottom", "bottomleft", "left", "topleft", "topright", "right" or "center".