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R Language –Presentation of Data : Online Course

by admin in Uncategorized

R line graphs

  • Function plot() is the main tool for 2D plotting in R.
  • If we have two vectors x, y of equal length, function plot(x,y) allows us to get the graph of y(x) dependence.
  • The function plot(x,y) takes parameters for specifying points in the diagram.
    1. Parameter 1 specifies points on the x-axis.
    2. Parameter 2 specifies points on the y-axis.
  • If only one variable is given, we will get a graph for which set vector provide the ordinate values and the points ordinal numbers are abscissas.
  • A line graph has a line that connects all the points in a diagram.
  • If you want to create line it is required plot function and type is “l”.

Some arguments of the plot() function:

Following arguments in details.

S.NOPARAMETERDESCRIPTION
1.vIt is a vector which contains the numeric values. x is specifies points on the x-axis. y is specifies points on the y-axis.
2.typechange the plot type. It accepts the following strings and has the given effect.”p” – points
“l” – lines
“b” – both points and lines
“c” – empty points joined by lines
“o” – overplotted points and lines
“s” and “S” – stair steps
“h” – histogram-like vertical lines
“n” – does not produce any points or lines
3.xlabIt is the label for the x-axis.
4.ylabIt is the label for the y-axis.
5.mainIt is the title of the chart.
6.colIt is used to give the color for both the points and lines
7pchpch is used to change the point shape format.
8cexUse cex=number to change the size of the points
9Legend()Legend takes as input the coordinates, text and the symbols to be interpreted.
10Itylty is the text sequence of four numbers from 1 to 9, for example: lty = “4241”.

Example : Single Line

Input: To draw a single line using type= “l” parameter
plot(1:10, main=”My Graph”, xlab=”The x-axis”, ylab=”The y axis”, type=”l”)
Output:

Example : Color and Line Width

Input: To draw line width and Colors using “col” and “lwd” parameter
plot(1:10, main=”My Graph”, xlab=”The x-axis”, ylab=”The y axis”, type=”l”, col=”red”, lwd = 2)
Output:

Color lines and Line Style

Input: The lines have been colored “col” and line style “lty” by the parameter of the plot() function.
vec = c(12,45,11,58,74)
plot(vec, type = ‘l’, col = ‘green’, lty=1)
Output:

Available parameter values for lty:

  • 0 removes the line
  • 1 displays a solid line
  • 2 displays a dashed line
  • 3 displays a dotted line
  • 4 displays a “dot dashed” line
  • 5 displays a “long dashed” line
  • 6 displays a “two dashed” line

Multiple line graphs on single plot

Input: To Draw multiple line on single plot
vec1 = c(12,45,11,58,74)
vec2 = c(45,12,1,87,10)
vec3 = c(10,4,15,56,25)
plot(vec1, type = ‘o’, col = ‘red’, xlab = ‘X-Axis’,
ylab = ‘Y-Axis’, main = ‘Line Graph’, ylim = c(0,100))
lines(vec2, type = “o”, col = “green”)
lines(vec3, type = “o”, col = “purple”)
Output: