program3

Implement an R function to generate a line graph depicting the trend of a time-series dataset, with separate lines for each group, utilizing ggplot2’s group aesthetic.

Introduction

This document demonstrates how to create a time-series line graph using

Step 1: Load necessary libraries

library(ggplot2)
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

library(tidyr)

#Convert timme-series data to a dataframe
class(AirPassengers)

[1] "ts"

Step 2: Load the Built-in AirPassengers Dataset

The AirPassengers dataset is a time series object in R.

We first convert it into a dataframe to use it with ggplot2.

• Date:

data <- data.frame(
  Date = seq(as.Date("1949-01-01"),
             by = "month",
             length.out = length(AirPassengers)),
  Passengers = as.numeric(AirPassengers),
  Year = as.factor(format(seq(as.Date("1949-01-01"),by
                              ="month", length.out = length(AirPassengers)), "%Y"))
)
#Display first few rows
head(data,n=20)

         Date Passengers Year
1  1949-01-01        112 1949
2  1949-02-01        118 1949
3  1949-03-01        132 1949
4  1949-04-01        129 1949
5  1949-05-01        121 1949
6  1949-06-01        135 1949
7  1949-07-01        148 1949
8  1949-08-01        148 1949
9  1949-09-01        136 1949
10 1949-10-01        119 1949
11 1949-11-01        104 1949
12 1949-12-01        118 1949
13 1950-01-01        115 1950
14 1950-02-01        126 1950
15 1950-03-01        141 1950
16 1950-04-01        135 1950
17 1950-05-01        125 1950
18 1950-06-01        149 1950
19 1950-07-01        170 1950
20 1950-08-01        170 1950

#Function to plot time-series trend
plot_time_series <- function(data, x_col, y_col, group_col, title="Air Passenger Trendds"){
  ggplot(data, aes_string(x= x_col, y= y_col, color=group_col, group= group_col))+
    geom_line(size = 1.2)+#Line graph
    geom_point(size=2)+ #Add points for clarity
    labs(title = title,
         x= "Year",
         y= "Number of Passengers",
         color = "Year")+ #Legend title
    theme_minimal()+
    theme(legend.position = "top")
  
}
#Call the function
plot_time_series(data, "Date", "Passengers", "Year", "Trend of Airline Passengers Over Time")

Warning: `aes_string()` was deprecated in ggplot2 3.0.0.
ℹ Please use tidy evaluation idioms with `aes()`.
ℹ See also `vignette("ggplot2-in-packages")` for more information.

Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
ℹ Please use `linewidth` instead.