Code
synthese %>%
filter(variable %in% c("Nombre de DI", "ETP en DI")) %>%
ggplot() + geom_line(aes(x = date, y = value, color = variable)) +
theme_minimal() + xlab("") + ylab("") +
scale_x_date(breaks = "2 months",
labels = date_format("%b %y")) +
# scale_color_manual(values = viridis(7)[1:6]) +
theme(legend.position = c(0.5, 0.8),
legend.title = element_blank())