How to plot a legend on this graph

The tidy way of doing this would be to join your data sets and reshape them into a long format but, it is posible to manually map aesthetics so you can get a legend, this is an example using a buil-in data frame


legend_colors <- c("Sepal" = "red", "Petal" = "blue")

ggplot() +
    geom_line(data = iris, aes(x = Sepal.Length, y = Sepal.Width, color = "Sepal")) +
    geom_line(data = iris, aes(x = Sepal.Length, y = Petal.Length, color = "Petal")) +
    scale_color_manual(values = legend_colors)

Created on 2021-08-05 by the reprex package (v2.0.0)

If you need more specific help, please provide a proper REPRoducible EXample (reprex) illustrating your issue.

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