Linear Coordinate System in ggplot2
The Linear coordinate system is the one that mostly uses the cartesian coordinate system and is the default coordinate system of the ggplot2. It consists of the origin, which is where the two axis, i.e., the x and y axis intersect. This system is mainly used for zooming, fixing coordinates, and flipping coordinates. There are three types of linear coordinate systems. They are as follows:
Zooming the plot using coord_cartesian()
The coord_cartesian() is used to zoom in and out on a figure using the ggplot2 without affecting the underlying data. When dealing with data that has extreme numbers or outliers that obscure the subtleties of the remaining data, this can be helpful. The “xlim” and “ylim” parameters of the “coord_cartesian()” function specify the x and y-axis boundaries, respectively.
Syntax:
coord_cartesian(xlim = NULL, ylim = NULL, expand = TRUE)
Parameters:
- xlim: It is used to provide the x-axis limits. It accepts a vector of two values that represent the minimum and maximum x-axis limits. The boundaries remain unchanged if NULL.
- ylim: It accepts a vector of two values that define the minimum and maximum y-axis limits. The boundaries remain unchanged if NULL.
- expand: The axis limits can be slightly enlarged to make sure that all data points are visible by using this option. The axis bounds are increased if TRUE (the default), and collapsed if FALSE.
Now, let us see how to zoom in on a particular area of a barplot using coord_cartesian()
Example: Original graph
R
# load ggplot2library(ggplot2)# Create sample datadata <- data.frame( Language = c("Python", "Java", "C++", "R", "Php"), Popularity = c(14, 25, 23, 30, 10))# Create a basic bar chartggplot(data, aes(x = Language, y = Popularity)) + geom_bar(stat = "identity") + labs(title = "Programming Language Popularity") + xlab("Language") + ylab("Popularity") |
Output:
Original Graph
Example: Graph after applying coord_cartesian()
R
# load ggplot2library(ggplot2)# Sample datadata <- data.frame( Language = c("Python", "Java", "C++", "C#", "JavaScript"), Popularity = c(14, 25, 23, 18, 10))# Create a bar chart using ggplotggplot(data, aes(x = Language, y = Popularity)) + geom_bar(stat = "identity", fill = "steelblue") + labs(title = "Programming Language Popularity", x = "Language", y = "Popularity") + # Set the y-axis limits to zoom in on y axis coord_cartesian(ylim = c(0, 15)) |
Output:
In this example, we enlarged the area of the plot using coord_cartesian(). This produced a map that only displays the bars that fall within that range, which makes it simpler to see the specifics of the data in that region.
Zoomed in coordinates with coord_cartesian()
Fixing Aspect Ratio with coord_fixed()
The fixed aspect ratio for the plot can be specified using the coord_fixed() function in ggplot2. When working with data where the relationship between the x and y variables is significant and should be maintained, this can be helpful. One argument, ratio, is required by the coord_fixed() method, and it determines the plot’s aspect ratio as the relationship between its y and x units. The x and y scales are modified to have the same range of data units per inch when the plot’s fixed aspect ratio is specified using the coord_fixed() function.
Syntax:
coord_fixed(ratio = 1, xlim = NULL, ylim = NULL)
Parameters:
- ratio: It is used to describe the plot’s aspect ratio, which is the ratio of the plot’s height to width. The plot has a square aspect ratio when the default value of 1 is used.
- xlim, ylim: It specifies the x-axis and y-axis boundaries. The boundaries are not altered if NULL.
Let us see how to set a fixed aspect ratio on a scatterplot using coord_fixed():
Example: Original graph
R
# load ggplot2library(ggplot2)# Create sample datadata <- data.frame( theta = seq(0, 2 * pi, length.out = 50), radius = rnorm(50))# Create a basic scatterplot with polar coordinateggplot(data, aes(x = theta, y = radius)) + geom_point() + labs(title = "Scatterplot with Polar Coordinates System") |
Output:
Original Graph
Example: Graph after applying coord_fixed()
R
# load ggplot2library(ggplot2)# Sample datadata <- data.frame(x = c(10, 20, 30, 40, 50), y = c(30, 60, 90, 120, 150))# Create a scatterplot using ggplotggplot(data, aes(x = x, y = y)) + geom_point() + labs(title = "With Fixed Aspect Ratio- SCATTERPLOT", x = "X-axis", y = "Y-axis") + # Set the aspect ratio to 1:1 coord_fixed(ratio = 1) |
Output:
In this example, a scatterplot was made. The plot was then given a fixed aspect ratio of 1:1 using coord_fixed(). This makes sure that the plot’s aspect ratio doesn’t change the relationship between the x and y variables.
Fixed Aspect Ratio with coord_fixed()
Swapping Axes with coord_flip()
A graph’s x and y axes can be flipped using the coord_flip() function in ggplot2. When working with data where the y variable should be shown horizontally and the x variable vertically, this can be helpful. Coord_flip() does not accept any arguments. The x and y axes of the plot are switched using the coord_flip() method, making the horizontal axis the vertical axis and vice versa.
Syntax:
coord_flip()
There are no parameters for the coord_flip() function.
Now, let us see the use of coord_flip() to change a bar chart’s axes.
Example: Original graph
R
# load ggplot2library(ggplot2)# Create sample datadata <- data.frame( x = c("P", "Q", "R", "S"), y = c(100, 80, 60, 40))# Create a basic bar chartggplot(data, aes(x = x, y = y)) + geom_bar(stat = "identity") + labs(title = "Bar Chart with Cartesian Coordinate System") + xlab("Category") + ylab("Value") |
Output:
Original Graph
Example: Graph after using coord_flip()
R
# load ggplot2library(ggplot2)# Create sample datadata <- data.frame( x = c("P", "Q", "R", "S"), y = c(100, 80, 60, 40))# Create a basic bar chartggplot(data, aes(x = x, y = y)) + geom_bar(stat = "identity") + labs(title = "Bar Chart with Cartesian Coordinate System-coord_flip") + xlab("Category") + ylab("Value") + # flipping axes coord_flip() |
Output:
In this example, we used a dataset of four categories and their values to build a bar chart. After switching the plot’s x and y axes using coord_flip(), the bar chart was transformed into a horizontal bar chart.
Flipped axis with coord_flip()
Coordinate systems in ggplot2
In R programming, ggplot2 is a well-liked library for data visualization. It offers a versatile method for producing a wide range of plots, including scatterplots, line plots, bar charts, histograms, and many more. Users of ggplot2 can produce visualizations that more clearly convey the patterns and relationships in their data by utilizing several coordinate systems.
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