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R - Bar Charts

A bar chart represents data in rectangular bars with length of the bar proportional to the value of the variable. R uses the function barplot() to create bar charts. R can draw both vertical and horizontal bars in the bar chart. In bar chart each of the bars can be given different colors.

Syntax

The basic syntax to create a bar-chart in R is −
barplot(H, xlab, ylab, main, names.arg, col)
Following is the description of the parameters used −
  • H is a vector or matrix containing numeric values used in bar chart.
  • xlab is the label for x axis.
  • ylab is the label for y axis.
  • main is the title of the bar chart.
  • names.arg is a vector of names appearing under each bar.
  • col is used to give colors to the bars in the graph.

Example

A simple bar chart is created using just the input vector and the name of each bar.
The below script will create and save the bar chart in the current R working directory.
# Create the data for the chart.
H <- c(7,12,28,3,41)

# Give the chart file a name.
png(file = "barchart.png")

# Plot the bar chart.
barplot(H)

# Save the file.
dev.off()
When we execute the above code, it produces the following result −

Bar Chart Labels, Title and Colors

The features of the bar chart can be expanded by adding more parameters. The main parameter is used to add title. The col parameter is used to add colors to the bars. The args.name is a vector having same number of values as the input vector to describe the meaning of each bar.

Example

The following script will create and save the bar chart in the current R working directory.
# Create the data for the chart.
H <- c(7,12,28,3,41)
M <- c("Mar","Apr","May","Jun","Jul")

# Give the chart file a name.
png(file = "barchart_months_revenue.png")

# Plot the bar chart.
barplot(H,names.arg = M,xlab = "Month",ylab = "Revenue",col = "blue",
main = "Revenue chart",border = "red")

# Save the file.
dev.off()
When we execute the above code, it produces the following result −

Group Bar Chart and Stacked Bar Chart

We can create bar chart with groups of bars and stacks in each bar by using a matrix as input values.
More than two variables are represented as a matrix which is used to create the group bar chart and stacked bar chart.
# Create the input vectors.
colors <- c("green","orange","brown")
months <- c("Mar","Apr","May","Jun","Jul")
regions <- c("East","West","North")

# Create the matrix of the values.
Values <- matrix(c(2,9,3,11,9,4,8,7,3,12,5,2,8,10,11),nrow = 3,ncol = 5,byrow = TRUE)

# Give the chart file a name.
png(file = "barchart_stacked.png")

# Create the bar chart.
barplot(Values,main = "total revenue",names.arg = months,xlab = "month",ylab = "revenue",
   col = colors)

# Add the legend to the chart.
legend("topleft", regions, cex = 1.3, fill = colors)

# Save the file.
dev.off()



Table of contents: 
1. R - Overview
2. R - Environment Setup
3. R - Basic Syntax
4. R - Data Types
5. R - Variables
6. R - Operators
7. R - Decision Making
8. R - Loops
9. R - Functions
10. R - Strings
11. R - Vectors
12. R - Matrices
13. R - Arrays
14. R - Factors
15. R - Data Frames
16. R - Packages
17. R - Data Reshaping
18. R - CSV Files
19. R - Excel Files
20. R - Binary Files
21. R - XML Files
22. R - JSON Files
23. R - Web Data
24. R - Database
25. R - Pie Charts
26. R - Bar Charts
27. R - Boxplots
28. R - Histograms
29. R - Line Graphs
30. R - Scatterplots
31. R - Mean, Median and Mode
32. R - Linear Regression
33. R - Multiple Regression
34. R - Logistic Regression
35. R - Normal Distribution
36. R - Binomial Distribution
37. R - Poisson Regression
38. R - Analysis of Covariance
39. R - Time Series Analysis
40. R - Nonlinear Least Square
41. R - Decision Tree
42. R - Random Forest
43. R - Survival Analysis
44. R - Chi Square Tests

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