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Now we can easily compare the scores obtained by the students under two different conditions, i.e., studying in a quiet
room vs studying in a noisy room. However, note that the graph does not tell us which line graph corresponds to which
condition. When, multiple graphs are included in the same figure, this information is included by specifying the labels
while invoking the plt.plot() function for each graph. These labels are displayed in a box within the graph when
the function plt.legend() is invoked. This is illustrated below (Fig 3.15):
>>> import matplotlib.pyplot as plt
>>> timeSpentStudying = [1, 2, 3, 4, 5]
>>> quietRoomScores = [63, 75, 82, 87, 93]
>>> noisyRoomScores = [58, 62, 68, 69, 75]
>>> plt.plot(timeSpentStudying, quietRoomScores, 'ro-', label='Quiet room')
>>> plt.plot(timeSpentStudying, noisyRoomScores, 'b<-', label='Noisy room')
>>> plt.xlabel('No of hours studied')
>>> plt.ylabel('Score')
>>> plt.title("Performance in a Noisy Room vs Quiet Room")
>>> plt.xticks(timeSpentStudying)
>>> plt.legend()
>>> plt.show()
Fig 3.15: Performance in a Noisy Room vs Quiet Room
In the following graph (Fig 3.16), we display the linear, quadratic, and cubic functions, for the values in the interval [0,
2.0] in steps of 0.2 (please see Program 1).
Program 1: To plot linear, quadratic, and cubic functions
01 import matplotlib.pyplot as plt
02 x = [0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0]
03 # Linear function
04 y1 = x
05 # Compute Squares
06 y2 = []
07 for value in x:
08 y2.append(value**2)
09 # Compute cubes
10 y3 = []
102 Touchpad Informatics Practices-XII

