Adding legend in ggplot2

Question

I have looked through similar questions and I have a feeling I have done everything. Still not getting the desire output. I am using ggplot2 and tidyquant packages to visualize data with 2 financial trends I am trying to display a legend that contains trends line coloron plot

data %>%
  ggplot(aes(date, price)) +
  geom_line() +
  geom_ma(ma_fun = SMA, n = 50, size = 1 , col = "red" , show.legend = TRUE)+
  geom_ma(ma_fun = SMA, n = 200, size = 1 , col = "blue", show.legend= TRUE)+
  theme_tq()

does it still not show the legend if you omit "+ theme_tq()" ? — Davide Passaretti, Apr 09 '18 at 12:06

score 5 · Accepted Answer · answered Apr 09 '18 at 12:07

5

Here you go:

library(tidyquant)
library(ggplot2)
data <- data.frame(date = 1:1000, price = cumsum(rnorm(1000)))
data %>%
  ggplot(aes(date, price)) +
  geom_line() +
  geom_ma(aes(color = 'MA50'),  ma_fun = SMA, n = 50, size = 1 ,show.legend = TRUE)+
  geom_ma(aes(color =  'MA200'), ma_fun = SMA, n = 200, size = 1 , show.legend = TRUE) +
  scale_colour_manual(name = 'Legend', 
                      guide = 'legend',
                      values = c('MA50' = 'red',
                                 'MA200' = 'blue'), 
                      labels = c('SMA(50)',
                                 'SMA(200)'))

answered Apr 09 '18 at 12:07

Martin Schmelzer

23,283
6
73
98

really should one add a manual scale to draw the legend? I have never used tidyquant, but this is a bit strange behaviour, IMO. – Davide Passaretti Apr 09 '18 at 12:11
You dont have to use a manual scale. But he wanted `red` and `blue` and not the default colors. Adding a nice title to the legend does not do any harm as well. – Martin Schmelzer Apr 09 '18 at 12:16
ok got it. I thought his problem was that he did not get any legend at all – Davide Passaretti Apr 09 '18 at 12:22
Great, Thanks Martin. Now worries, nice title is already on the plot ;) – Ann Apr 09 '18 at 12:52

Adding legend in ggplot2

1 Answers1