2D Line Plot in MATLAB

‘2D’ stands for 2-dimensional and a 2D line is a line that is moved in 2-dimensions. A line in 2D means that we could move in forward and backward direction but also in any direction like left, right, up, down.

In MATLAB we have a function named plot() which allows us to plot a line in 2 directions. 

Syntax:

plot(X,Y)

where X and Y represent the x and the y axis of the plane. The X and Y both are can be vectors or matrices but there are some conditions to plot the graph and these conditions are mentioned below:

Condition 1: If X and Y both are vectors then they must be of equal length.

Condition 2: If X and Y both are Matrices then they must be of equal size.

Condition 3: If one of X or Y is a vector and the other is a matrix, then the matrix must have dimensions such that one of its dimensions equals the vector length. 

Condition 4: If one is a scalar and the other is either a scalar or a vector, then discrete points must be plotted.

Now let’s move to some examples.

Example 1: Draw a simple line:

MATLAB

% coordinates of the x-axis
x=[10,20,30,40,50]

% coordinates of the y-axis
y=[100,200,300,400,500]

% plot function is used to plot the
% line according to the coordinates
plot(x,y)

% to put grid on the graph
grid on

Output : 

Example 2: Draw a line with only 1 axis coordinates as input:

Note: If you give only 1 axis then the plot() function takes it as coordinates of the y-axis and by default gives values to the x-axis starting from 1, 2, 3, up to y coordinates.

MATLAB

% coordinates of axis
y=[100,200,300,400,500]

% plot function is used to plot the
% line according to the coordinates
plot(x,y)

% to put grid on the graph
grid on

Output : 

Example 3: Draw more than 1 line on the same graph with axis names:

MATLAB

% coordinates of x-axis
x=[10,20,30,40,50]

% coordinates of y-axis of line 1
% represented by blue color
y1=[100,500,200,100,0]

% coordinates of y-axis of line 2
% represented by red color
y2=[400,100,0,200,300]

% coordinates of y-axis of line 3
% represented by yellow color
y3=[200,300,400,100,500]

% plot function to plot the lines on graph
plot(x,y1,x,y2,x,y3)

% to add grid on graph
grid on

% name of x axis
xlabel('x')

% name of y axis
ylabel('y')

Output :

Example 4: Now the value of the y-axis is given as matrix instead of vector:

MATLAB

% coordinates of x-axis
x=[1,2,3,4,5]

% coordinates of y-axis in form of matrix
% magic(n) matrix is a n*n matrix
% in which value scattered from 1 to n^2
% with equal row and columns sum
y=magic(5)

% plot function
plot(x,y)

% to add grid
grid on

% add name on axis
xlabel('x')
ylabel('y')

Output: 

Example 5: Now we plot the graph by using 2 y-axis one is on the left side another is on the right side.

MATLAB

% coordinates of x-axis
x=[1,2,3,4,5]

% coordinates of y-axis
y=[50,40,30,20,10]

% assigning left side to the above
% coordinates
yyaxis left

% plot graph of left y-axis
plot(x,y)

% coordinates of y-axis
y=[10,20,30,40,50]

% assigning right side to the above
% coordinates
yyaxis right

% plot graph of right y-axis
plot(x,y)

% put grid on graph
grid on

% name of x-axis
xlabel('x')

% name of left side y coordinates
yyaxis left
ylabel('Left Side')

% name of right side y coordinates
yyaxis right
ylabel('Right Side')

Output: