Ggplot2 package (part1)

It is a graphic package implemented in R, it allows to make graphs in a very flexible way because it contains many different commands to perform specific functions when creating and manipulating graphs. In addition, this graphic package has an underlying grammar in layers, so that it is composed of independent components. These independent components can be combined in many different ways to make or modify the graphs. Each graph is made up of a few equal components: data, visual marks that represent data points (geoms), and a coordinate system. The necessary variables for the ggplot command are the data to use in data frame format and know which variables we will use as x and y:

       ggplot (df, aes (x, y, ))

You can add more layers to the previous ggplot using the + operator, so the code is explicit as to which layers were added and in the order they were added.

here we will use the dataset iris:

head(iris)

##   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
## 1          5.1         3.5          1.4         0.2  setosa
## 2          4.9         3.0          1.4         0.2  setosa
## 3          4.7         3.2          1.3         0.2  setosa
## 4          4.6         3.1          1.5         0.2  setosa
## 5          5.0         3.6          1.4         0.2  setosa
## 6          5.4         3.9          1.7         0.4  setosa

summary(iris)

##   Sepal.Length    Sepal.Width     Petal.Length    Petal.Width   
##  Min.   :4.300   Min.   :2.000   Min.   :1.000   Min.   :0.100  
##  1st Qu.:5.100   1st Qu.:2.800   1st Qu.:1.600   1st Qu.:0.300  
##  Median :5.800   Median :3.000   Median :4.350   Median :1.300  
##  Mean   :5.843   Mean   :3.057   Mean   :3.758   Mean   :1.199  
##  3rd Qu.:6.400   3rd Qu.:3.300   3rd Qu.:5.100   3rd Qu.:1.800  
##  Max.   :7.900   Max.   :4.400   Max.   :6.900   Max.   :2.500  
##        Species  
##  setosa    :50  
##  versicolor:50  
##  virginica :50  
##                 
##                 
## 

Some examples:

1. Plot using dots:

require('ggplot2')

## Loading required package: ggplot2

## Warning: package 'ggplot2' was built under R version 3.4.1

ggplot(iris, aes(iris$Petal.Length, iris$Petal.Width)) +
  geom_point(aes(color=Species, shape = Species)) +
  xlab("Petal Length") +
  ylab("Petal Width") +
  ggtitle("IRIS1")

ggplot(iris, aes(iris$Petal.Length, iris$Petal.Width)) +
  geom_point(aes(color = Petal.Length, shape = Species), size = 2) +
  geom_vline(aes(xintercept = mean(Petal.Length)), color = "red", linetype = "longdash")+
  geom_hline(aes(yintercept = mean(Petal.Width)), color = "red", linetype = "longdash") +
  scale_color_gradient(low = "pink", high = "blue") +
  xlab("Petal Length") +
  ylab("Petal Width") +
  ggtitle("IRIS2")

2. Dots with a grid:

ggplot(iris, aes(iris$Petal.Length, iris$Petal.Width)) +
  geom_point(aes(color=Species, shape = Species)) +
  facet_grid(~Species) +
  xlab("Petal Length") +
  ylab("Petal Width") +
  ggtitle("IRIS3")

3. Density plots:

ggplot(iris, aes(Petal.Width, fill= Species, color = Species)) +
  geom_density(alpha = 0.5) +
  xlab("Petal Width") +
  ggtitle("IRIS4")

ggplot(iris, aes(Petal.Width, fill= Species, color = Species)) +
  geom_density(alpha = 0.5, position = 'stack') +
  xlab("Petal Width") +
  ggtitle("IRIS5")

4. Boxplots:

ggplot(iris, aes(iris$Petal.Length, iris$Petal.Width)) +
  geom_boxplot(aes(fill=Species)) + 
  ylab("Sepal Length") +
  ggtitle("IRIS6")

ggplot(iris, aes(iris$Species, iris$Petal.Length)) +
  geom_boxplot(aes(fill=Species)) + 
  stat_summary(fun.y= max, geom="point", shape=2, size=3) +
  stat_summary(fun.y= min, geom="point", shape=1, size=3) +
  stat_summary(fun.y= mean, geom="point", shape=0, size=3) +
  xlab("Species") +
  ylab("Sepal Length") +
  ggtitle("IRIS7")