Page 264 - Data Science class 11
P. 264
Histograms plot quantitative data with ranges of the data grouped into bins or intervals, while bar charts plot
categorical data.
The main advantages of a histogram are its simplicity and versatility. It can be used in many different situations to
offer an insightful look at frequency distribution. For example, it can be used in sales and marketing to develop the
most effective pricing plans and marketing campaigns.
R creates histogram using hist() function. This function takes a vector as an input and uses some more parameters
to plot histograms.
Syntax
The basic syntax for creating a histogram using R is:
hist(v,main,xlab,xlim,ylim,breaks,col,border)
The following are the details of the parameters used in the above syntax:
• v: is a vector containing numeric values used in histogram.
• main: indicates title of the chart.
• col: is used to set the colour of the bars.
• border: is used to set the border colour of each bar.
• xlab: is used to give a description of the x-axis.
• xlim: is used to specify the range of values on the x-axis.
• ylim: is used to specify the range of values on the y-axis.
• breaks: is used to mention the width of each bar.
The script given below will create and save the histogram in the current R working directory.
Type the following code snippet in the script:
# Creating data for the graph.
v <- c(9,13,21,8,36,22,12,41,31,33,19)
# Giving chart file a name.
png(file = "histogram.png")
# Creating the histogram.
hist(v,xlab = "Weight",col = "yellow",border = "blue")
# Save the file.
dev.off()
On execution of the above code, it produces the following result:
262 Touchpad Data Science-XI

