Odtnhj

I want to plot two lines, one solid and another one dotted, both with different colors. I'm having trouble dealing with the legends for this plot. Take this example:

library(ggplot2)
library(reshape2)

df = data.frame(time = 0:127,
 mean_clustered = rnorm(128),
 mean_true = rnorm(128)
)
test_data_long <- melt(df, id="time") # convert to long format
p = ggplot(data=test_data_long,
 aes(x=time, y=value, colour=variable)) +
 geom_line(aes(linetype=variable)) +
 labs(title = "", x = "Muestras", y = "Amplitud", color = "Spike promedion") +
 scale_color_manual(labels = c("Hallado", "Real"), values = c("blue", "red")) +
 xlim(0, 127)

print(p)

Two legends appear, and on top of it, none of them is correct (the one with the right colors has wrong line styles, and the one with the right line styles has all other things wrong).

Why is this happening and how can I get the right legend to appear?

You need to ensure all the aesthetic mappings match between the different aesthetics you're using:

library(ggplot2)
library(reshape2)

data.frame(
 time = 0:127,
 mean_clustered = rnorm(128),
 mean_true = rnorm(128)
) -> xdf

test_data_long <- melt(xdf, id = "time")

ggplot(
 data = test_data_long,
 aes(x = time, y = value, colour = variable)
) +
 geom_line(aes(linetype = variable)) +
 scale_color_manual(
 name = "Spike promedion", labels = c("Hallado", "Real"), values = c("blue", "red")
 ) + 
 scale_linetype(
 name = "Spike promedion", labels = c("Hallado", "Real")
 ) +
 labs(
 x = "Muestras", y = "Amplitud", title = ""
 ) +
 xlim(0, 127)

Might I suggest also using theme parameters to adjust the legend title:

ggplot(data = test_data_long, aes(x = time, y = value, colour = variable)) +
 geom_line(aes(linetype = variable)) +
 scale_x_continuous(name = "Muestras", limits = c(0, 127)) +
 scale_y_continuous(name = "Amplitud") +
 scale_color_manual(name = "Spike promedio", labels = c("Hallado", "Real"), values = c("blue", "red")) + 
 scale_linetype(name = "Spike promedio", labels = c("Hallado", "Real")) +
 labs(title = "") +
 theme(legend.title = element_text(margin = margin(b=15)))