Wrong coloring in ggplot line graphs - ggplot2

Question

I have created a ggplot graph with three lines. Each line represents a different column in a data frame and colored in a different color. For some reason, the colors in the final graph are not coordinated to the code.
The data frame:
Scenario 1 Scenario 2 Scenario 3 Years
0.0260 0.0340 0.0366 1
0.0424 0.0562 0.0696 2
0.0638 0.0878 0.1150 3
0.0848 0.1280 0.1578 4
0.1096 0.1680 0.2074 5
0.1336 0.2106 0.2568 6
This is the code:
ggplot(ext2, aes(x = Years))+
geom_line(aes(y = `Scenario 1`, color = "darkblue"))+
geom_line(aes(y = `Scenario 2`, color = "darkred"))+
geom_line(aes(y = `Scenario 3`, color = "darkgreen"))+
xlab("Years")+
ylab("Quasi - extinction probability")+
ggtitle("2 mature individuals")+
geom_segment(aes(x = 45,y = 0.5, xend = 45, yend = 1.1),linetype = "longdash")+
geom_segment(aes(x = 75,y = 0.2, xend = 75, yend = 0.5),linetype = "longdash")+
geom_segment(aes(x = 0,y = 0.5, xend = 100, yend = 0.5),linetype = "longdash")+
geom_segment(aes(x = 0,y = 0.2, xend = 100, yend = 0.2),linetype = "longdash")+
geom_text(x = 20, y = 0.80, label = "CE")+
geom_text(x = 40, y = 0.35, label = "EN")+
scale_colour_manual(values = c("darkblue", "darkred","darkgreen"), labels = c("Scenario 1","Scenario 2","Scenario 3"))+
theme(legend.title = element_blank())+
theme_minimal()
and this is the graph:
Click here to see graph
The problem is that what I defined as 'scenario 3' in the code is actually a representation of 'scenario 2' in the data frame. You can see it according to the values under scenario 2 in the data frame.

Answer 1

For ggplot, the data needs to be in long format before you plot. Then, you can make "Scenarios" (i.e., name) the group, so that you can manually color the individual lines (i.e., with scale_colour_manual).
library(tidyverse)
ext_long <- ext2 %>%
pivot_longer(!Years)
ggplot(ext_long, aes(x = Years, color = name)) +
geom_line(aes(y = value)) +
xlab("Years") +
ylab("Quasi - extinction probability") +
ggtitle("2 mature individuals") +
geom_segment(aes(
x = 45,
y = 0.5,
xend = 45,
yend = 1.1
), linetype = "longdash") +
geom_segment(aes(
x = 75,
y = 0.2,
xend = 75,
yend = 0.5
), linetype = "longdash") +
geom_segment(aes(
x = 0,
y = 0.5,
xend = 100,
yend = 0.5
), linetype = "longdash") +
geom_segment(aes(
x = 0,
y = 0.2,
xend = 100,
yend = 0.2
), linetype = "longdash") +
geom_text(x = 20, y = 0.80, label = "CE") +
geom_text(x = 40, y = 0.35, label = "EN") +
scale_colour_manual(
values = c("darkblue", "darkred", "darkgreen"),
labels = c("Scenario 1", "Scenario 2", "Scenario 3")
) +
theme(legend.title = element_blank()) +
theme_minimal()
Output (only have a small part of the data, which is the reason the lines do not extend across the graph)
Data
ext2 <- structure(
list(
Scenario.1 = c(0.026, 0.0424, 0.0638, 0.0848,
0.1096, 0.1336),
Scenario.2 = c(0.034, 0.0562, 0.0878, 0.128,
0.168, 0.2106),
Scenario.3 = c(0.0366, 0.0696, 0.115, 0.1578,
0.2074, 0.2568),
Years = 1:6
),
class = "data.frame",
row.names = c(NA,-6L)
)