How to change the colors of geom_points in R

Question

library(tidyr)
library(dplyr)
library(ggplot2)
library(lubridate)

Suppose the following df:

Ano<-c(2012:2020)
Janeiro<-c(112,127,121,131,150,158,137,165,164)
Fevereiro<-c(101,101,94,114,126,119,122,138,144)
Março<-c(97,101,101,123,126,138,137,154,114)
Abril<-c(97,94,97,122,125,141,129,142,6)
Maio<-c(96,98,98,136,126,135,136,144,4)

fen<-data.frame(Ano, Janeiro, Fevereiro, Março, Abril, Maio)

After: Use "Gather" to put the data in Tidy format; Use "mutate" along with "ymd" and "Paste" to put years in "Date" format; Use "select" to select the columns that interest me; Use "arrange" to arrange in chronological order; I use "ggplot"+ "geom-line" and "geom_point" to create the chart.

fen %>% 
  gather(mes, n_voos, c(Janeiro:Maio)) %>% 
  mutate(dt=ymd(paste(Ano, mes, "1"))) %>% 
  select(dt, n_voos) %>% 
  arrange(dt) %>% 
  ggplot()+
  geom_line(aes(dt, n_voos))+
  geom_point(aes(dt, n_voos))

The result is:

My question: Is there any way I can COLOR the dots according to the months? For example: I would like every month of January with the color blue, all of February with the color green, all of March black, and so on.

I tried to add a "col=dt" in the last line, but the result generated a change in the colors of the dots according to the YEARS. It was like this:

fen %>% 
  gather(mes, n_voos, c(Janeiro:Maio)) %>% 
  mutate(dt=ymd(paste(Ano, mes, "1"))) %>% 
  select(dt, n_voos) %>% 
  arrange(dt) %>% 
  ggplot()+
  geom_line(aes(dt, n_voos))+
  geom_point(aes(dt, n_voos, col=dt))

Stayed like this:

Answer 1

To color according to the months, you should use mes in aes(color = mes), not the date dt, as it is in the question code.
Note that despite the gather function and be the form used in the past, the package tidyr has now help('pivot_longer'), the recommended form.

fen %>%
  pivot_longer(
    cols = Janeiro:Maio,
    names_to = "mes",
    values_to = "n_voos"
  ) %>%
  mutate(dt = ymd(paste(Ano, mes, "1")),
         mes = factor(mes, levels = c("Janeiro", "Fevereiro", "Março", "Abril", "Maio"))) %>%
  ggplot(aes(dt, n_voos)) +
  geom_line() +
  geom_point(aes(color = mes))