legend in ggplot2

Dear Ivan,

You're making things too complicated.

ggplot(mydata, aes(x = Spot, y = Value)) +
  geom_boxplot(aes(colour = Equipment), outlier.colour = "red") +
  geom_jitter() +
  facet_wrap(~Equipment, scales = "free_y") +
  scale_colour_manual(values = c(Leeb = "blue", Shore = "red"))

Best regards,

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature 
and Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium

To call in the statistician after the experiment is done may be no 
more than asking him to perform a post-mortem examination: he may be 
able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does 
not ensure that a reasonable answer can be extracted from a given body 
of data. ~ John Tukey

2017-02-02 14:59 GMT+01:00 Ivan Calandra <calandra at rgzm.de 
<mailto:calandra at rgzm.de>>:

    Dear useRs,

    I have been using base graphics since a long time and I'm
    currently trying to switch to ggplot2. I'm struggling with the
    legend (which probably means that my graphic commands are not
    optimal).
    I have copied the output from dput(mydata) at the end of the email.

    Here is what I have tried:
    library(ggplot2)
    library(cowplot)
    colo <- c("#F8766D", "#00BFC4")
    p1 <- ggplot(data=mydata[mydata$Equipment=="Shore",],
    aes(x=Spot,y=Value)) +
    geom_boxplot(outlier.size=2,fill=colo[1],outlier.color=colo[1]) +
    geom_jitter()
    p2 <- ggplot(data=mydata[mydata$Equipment=="Leeb",],
    aes(x=Spot,y=Value)) +
    geom_boxplot(outlier.size=2,fill=colo[2],outlier.color=colo[2]) +
    geom_jitter()
    plot_grid(p1, p2, nrow=2, ncol=1)

    The plot is fine, but there is no legend at all. I know this has
    to do with 'color' and 'fill' arguments to aes(), but I got lost
    with all of this...
    Ideally, I am looking for this kind of structure in the legend:
    Equipment
        [red box] Shore
        [blue box] Leeb
    Points
        [black dot] Measurements
        [red/blue dot] Outliers

    Thank you in advance for your help!
    Bests,
    Ivan


    mydata <- structure(list(Equipment = structure(c(1L, 1L, 1L, 1L,
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
    1L, 1L,
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
    2L, 2L, 2L, 2L, 2L, 2L), .Label = c("Leeb", "Shore"), class =
    "factor"), Spot = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
    1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L,
    3L, 3L, 3L, 3L, 3L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L,
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
    3L, 3L, 3L), .Label = c("1", "2", "3"), class = "factor"),
    Measurement = structure(c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L,
    1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 1L, 2L, 3L, 4L, 5L, 6L,
    7L, 8L, 9L, 10L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 1L, 2L,
    3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L,
    9L, 10L), .Label = c("1","2", "3", "4", "5", "6", "7", "8", "9",
    "10"), class = "factor"), Value = c(540, 640, 587, 593, 677, 675,
    626, 625, 635, 645, 492, 538, 560, 565, 560, 543, 560, 555, 580,
    577, 645, 645, 667, 658!
    , 652, 667, 652, 659, 669, 671, 89, 90.5, 93, 91, 91.5, 94, 94,
    91.5, 92.5, 91.5, 82, 82, 78.5, 84.5, 83.5, 87, 88, 88.5, 83.5,
    88, 89, 87, 87, 88, 92, 90.5, 88, 90.5, 93, 92.5)), .Names =
    c("Equipment", "Spot", "Measurement", "Value"), row.names = c(1L,
    2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L,
    17L, 18L, 19L, 20L, 21L, 22L, 23L, 24L, 25L, 26L, 27L, 28L, 29L,
    30L, 101L, 102L, 103L, 104L, 105L, 106L, 107L, 108L, 109L, 110L,
    111L, 112L, 113L, 114L, 115L, 116L, 117L, 118L, 119L, 120L, 121L,
    122L, 123L, 124L, 125L, 126L, 127L, 128L, 129L, 130L), class =
    "data.frame")


    -- 


    --
    Ivan Calandra, PhD
    MONREPOS Archaeological Research Centre and
    Museum for Human Behavioural Evolution
    Schloss Monrepos
    56567 Neuwied, Germany
    calandra at rgzm.de <mailto:calandra at rgzm.de>
    +49 (0) 2631 9772-243 <tel:%2B49%20%280%29%202631%209772-243>
    https://www.researchgate.net/profile/Ivan_Calandra
    <https://www.researchgate.net/profile/Ivan_Calandra>
    https://rgzm.academia.edu/IvanCalandra
    <https://rgzm.academia.edu/IvanCalandra>
    https://publons.com/author/705639/
    <https://publons.com/author/705639/>