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10 Examples to Grasp ggplot2: Line plots | by Soner Yıldırım | Oct, 2022


Plotting bundle for R

Picture by Johannes Andersson on Unsplash

The way you ship data is simply as essential as the data itself. Knowledge visualization is an crucial instrument for delivering data, storytelling, or evaluation in information science.

The 2 largest gamers within the information science ecosystem are Python and R. Each have quite a few packages to expedite and simplify the frequent duties.

On this article, we’ll go over 10 examples to discover ways to create and customise line plots with ggplot2, which is a knowledge visualization bundle in tidyverse, a set of R packages for information science.

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We are going to use 3 totally different datasets within the examples. You’ll be able to obtain them from the datasets repository on my GitHub web page.

The primary one is a CSV file that comprises the Apple inventory costs in 2022. Let’s first create a knowledge desk through the use of the fread operate of the information desk bundle.

library(information.desk)
library(ggplot2)
apple <- fread("datasets/apple_stock_prices_2022.csv")head(apple)
# output
Date Excessive Low Open Shut Quantity Adj Shut
1: 2022-01-03 182.88 177.71 177.83 182.01 104487900 181.2599
2: 2022-01-04 182.94 179.12 182.63 179.70 99310400 178.9595
3: 2022-01-05 180.17 174.64 179.61 174.92 94537600 174.1992
4: 2022-01-06 175.30 171.64 172.70 172.00 96904000 171.2912
5: 2022-01-07 174.14 171.03 172.89 172.17 86709100 171.4605
6: 2022-01-10 172.50 168.17 169.08 172.19 106765600 171.4804

Instance 1

We are going to create a easy line plot that exhibits the information on the x-axis and shutting worth on the y-axis.

ggplot(apple, aes(x = Date, y = Shut)) + 
geom_line()

The ggplot operate specifies the information and the mappings to x and y. The aes represents aesthetic mappings that describe how variables within the information are mapped to visible properties of geoms (e.g. geom_line).

The geom_line is the operate to attract a line plot. Right here is the output of the above code snippet:

(picture by creator)

Instance 2

We are able to do many customizations on the looks. Let’s change the road measurement, and shade, which could be achieved within the geom_line operate.

ggplot(apple, aes(x = Date, y = Shut)) + 
geom_line(measurement = 1.2, shade = "blue")
(picture by creator)

We are able to additionally make it a dashed line utilizing the linestyle parameter (linestyle = “dashed”).

Instance 3

The vary on the y axis is routinely outlined based mostly on the values within the dataset. Nonetheless, it may be modified utilizing the ylim operate.

The defaults are normally superb however we generally want to regulate them to maintain an ordinary between a number of plots or have an axis ranging from zero. Let’s set the vary to 100–200.

ggplot(apple, aes(x = Date, y = Shut)) + 
geom_line(shade = "darkgreen") +
ylim(100, 200)
(picture by creator)

Instance 4

We are able to add factors to point the situation of information factors. That is useful after we would not have loads of information factors (i.e. the density of observations is low).

On this instance, we’ll use the measurements dataset.

measurements <- fread("datasets/measurements.csv")measurements
# output
day worth
1: 1 80
2: 2 93
3: 3 94
4: 4 76
5: 5 63
6: 6 64
7: 8 85
8: 9 64
9: 10 95

Let’s create a line plot that exhibits the times on the x-axis and the values on the y-axis. We may also add factors utilizing the geom_point operate.

ggplot(measurements, aes(x = day, y = worth)) + 
geom_line() +
geom_point()
(picture by creator)

The factors are positioned the place now we have an commentary within the dataset. As an example, the dataset doesn’t have day 7 so it isn’t proven.

Instance 5

Within the earlier instance, the x values of the observations will not be very clear. In an effort to present every day worth on the x-axis, we will convert it to an element and use the group parameter of the ggplot operate.

measurements[, day := factor(day)]ggplot(measurements, aes(x = day, y = worth, group = 1)) + 
geom_line() +
geom_point()
(picture by creator)

Instance 6

We are able to have a number of traces on a line plot. We are going to use one other dataset for this instance, which comprises the inventory costs of Apple and Google in September, 2022.

inventory <- fread("datasets/apple_google_stock_prices_092022.csv")head(inventory)
# output
Date Excessive Low Open Shut Quantity Adj Shut Inventory
1: 2022-09-01 158.42 154.67 156.64 157.96 74229900 157.96 AAPL
2: 2022-09-02 160.36 154.97 159.75 155.81 76905200 155.81 AAPL
3: 2022-09-06 157.09 153.69 156.47 154.53 73714800 154.53 AAPL
4: 2022-09-07 156.67 153.61 154.82 155.96 87449600 155.96 AAPL
5: 2022-09-08 156.36 152.68 154.64 154.46 84923800 154.46 AAPL
6: 2022-09-09 157.82 154.75 155.47 157.37 68028800 157.37 AAPL

The inventory column signifies the identify of the inventory.

For every day, now we have two totally different values, one for Apple and one for Google. Thus, if we plot the date and shutting worth as we did earlier, we find yourself having a plot as proven beneath:

(picture by creator)

We have to present the Apple and Google inventory values with totally different traces. There are a number of alternative ways of doing this. As an example, we will use the color parameter and specify the column that differentiates Apple and Google.

ggplot(inventory, aes(x = Date, y = Shut, color = Inventory)) + 
geom_line()
(picture by creator)

Instance 7

Let’s recreate the earlier plot however utilizing totally different line types for Apple and Google. We simply want to make use of the linetype parameter as a substitute of the color.

ggplot(inventory, aes(x = Date, y = Shut, linetype = Inventory)) + 
geom_line(measurement = 1.2)
(picture by creator)

Instance 8

In examples 4 and 5, we added factors to mark observations within the dataset. The scale and form of those factors can be custom-made.

Let’s add factors to the plot in instance 7 and in addition change the worth vary for y-axis.

ggplot(inventory, aes(x = Date, y = Shut, shade = Inventory)) + 
geom_line() +
geom_point(measurement = 3, form = 22, fill = "white") +
ylim(90, 200)
(picture by creator)

Instance 9

We could need to change the default axis labels or add a title to a plot. Let’s make our plot extra informative and interesting by doing so.

The labs operate can be utilized for including a title and subtitle. The axis labels could be modified utilizing the xlab and ylab capabilities.

ggplot(inventory, aes(x = Date, y = Shut, shade = Inventory)) + 
geom_line(measurement = 1) +
labs(title = "Apple vs Google Inventory Costs",
subtitle = "September, 2022") +
xlab("") +
ylab("Closing Worth")
(picture by creator)

Instance 10

We are able to add a theme to the plots, which permits for making loads of customizations together with:

  • Altering the font measurement and elegance of title and subtitle
  • Altering the font measurement and elegance of axis labels
  • Altering the font measurement, fashion, and orientation of tick marks

Let’s use these to customise the plot within the earlier instance.

ggplot(inventory, aes(x = Date, y = Shut, shade = Inventory)) + 
geom_line(measurement = 1) +
labs(title = "Apple vs Google Inventory Costs",
subtitle = "September, 2022") +
xlab("") +
ylab("Closing Worth") +
theme(
plot.title = element_text(measurement = 18, face = "daring.italic"),
plot.subtitle = element_text(measurement = 16, face = "daring.italic"),
axis.title.y = element_text(measurement = 14, face = "daring"),
axis.textual content.x = element_text(measurement = 12),
axis.textual content.y = element_text(measurement = 12)
)
(picture by creator)

Ggplot2 is a extremely environment friendly library that gives a large amount of flexibility. I believe it’s just like Matplotlib when it comes to how we will customise just about something on a plot.

The examples on this article cowl most of what it’s essential to create and customise line plots. There will likely be some edge circumstances the place it’s essential to do some additional customizations however you may fear about them with regards to that time.

Thanks for studying. Please let me know in case you have any suggestions.

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