Histograms

set.seed(1234)
wdata=data.frame(
  sex = factor(rep(c("F","M"),each = 200)),
  weight = c(rnorm(200,56),rnorm(200,58))
)

head(wdata,4)

##   sex   weight
## 1   F 54.79293
## 2   F 56.27743
## 3   F 57.08444
## 4   F 53.65430

Now let load dplyr

library(dplyr)

## 
## Attaching package: 'dplyr'

## The following objects are masked from 'package:stats':
## 
##     filter, lag

## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union

mu <- wdata %>% 
  group_by(sex) %>% 
  summarise(grp.mean = mean(weight))

Now lets load the plotting package

library(ggplot2)

theme_set(
  theme_classic() +
    theme(legend.position ="bottom")
  
)

Now lets create a ggplot object

a <- ggplot(wdata, aes(x = weight))

a + geom_histogram(bins = 30, color = "black",fill="grey") + 
  geom_vline(aes(xintercept = mean(weight)), 
          linetype ="dashed",size = 0.6 )

## Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
## ℹ Please use `linewidth` instead.
## This warning is displayed once every 8 hours.
## Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
## generated.

Now lets change the color by group

a + geom_histogram(aes(color = sex), fill="white", position = "identity")+
  scale_color_manual(values= c("#00AFBB","#E7B800"))

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

a + geom_histogram(aes(color = sex, fill=sex), position = "identity")+
  scale_color_manual(values= c("#00AFBB","#E7B800")) +
  scale_fill_manual(values = c("indianred","lightblue1"))

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

What if we want to combine density plot and histograms?

a + geom_histogram(aes(y = stat(density)),
                   color = "black", fill = "white") +
  geom_density(alpha = 0.2, fill = "#FF6666")

## Warning: `stat(density)` was deprecated in ggplot2 3.4.0.
## ℹ Please use `after_stat(density)` instead.
## This warning is displayed once every 8 hours.
## Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
## generated.

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

a + geom_histogram(aes(y = stat(density), color = sex), 
                   fill = "white", position = "identity")+
  geom_density(aes(color = sex), size = 1) +
  scale_color_manual(values = c("indianred","lightblue1"))

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.