desde ontem eu estou lendo respostas e sites para combinar e alinhar em um gráfico umhistogram e umboxplot gerado usandoggplot2 pacote.

Esta questão difere das outras porque oboxplot chart precisa ser reduzido emheight ealigned para a margem externa esquerda dohistogram.

Considerando o seguinte conjunto de dados:

my_df <- structure(list(id = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 
28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 
44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 
60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 
76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 
92, 93, 94, 95, 96, 97, 98, 99, 100), value= c(18, 9, 3, 
4, 3, 13, 12, 5, 8, 37, 64, 107, 11, 11, 8, 18, 5, 13, 13, 14, 
11, 11, 9, 14, 11, 14, 12, 10, 11, 10, 5, 3, 8, 11, 12, 11, 7, 
6, 6, 4, 11, 8, 14, 13, 14, 15, 10, 2, 4, 4, 8, 15, 21, 9, 5, 
7, 11, 6, 11, 2, 6, 16, 5, 11, 21, 33, 12, 10, 13, 33, 35, 7, 
7, 9, 2, 21, 32, 19, 9, 8, 3, 26, 37, 5, 6, 10, 18, 5, 70, 48, 
30, 10, 15, 18, 7, 4, 19, 10, 4, 32)), row.names = c(NA, 100L
), class = "data.frame", .Names = c("id", "value"))

Eu gerei o boxplot:

require(dplyr)
require(ggplot2)
my_df %>% select(value) %>%
        ggplot(aes(x="", y = value)) +
        geom_boxplot(fill = "lightblue", color = "black") + 
        coord_flip() +
        theme_classic() +
        xlab("") +
        theme(axis.text.y=element_blank(),
              axis.ticks.y=element_blank())

e eu gerei o histograma

my_df %>% select(id, value) %>%
        ggplot() +
        geom_histogram(aes(x = value, y = (..count..)/sum(..count..)),
                       position = "identity", binwidth = 1, 
                       fill = "lightblue", color = "black") +
        ylab("Relative Frequency") +
        theme_classic()

O resultado que pretendo obter é um único gráfico, como:

Observe que o boxplot deve serreduzido em altura e acarrapatos devem estar exatamente alinhados para dar uma perspectiva diferente do mesmo visual.