Matplotlib

Question 1

What is Matplotlib

Answer 1

Low level graph plotting library. For visualization.

Question 2

Via python, show the matplotlib version

Answer 2

import matplotlib

print(matplotlib.__version__)

Remember, __version__ is a dunder method.

Question 3

We will primarily be using only one submodule for matplotlib. Import it and rename it under the name that is often given to it by developers.

Answer 3

import matplotlib.pyplot as plt

Question 4

Draw a line in a diagram from position (0,0) ro (6,250)

Answer 4

import matplotlib.pyplot as plt
import numpy as np

xpoints = np.array([0, 6])
ypoints = np.array([0, 250])

plt.plot(xpoints, ypoints)
plt.show()

numpy is only used to create arrays (elements must be of the same type and are in fixed locations allowing them to be summoned via index numbers.)

Plot() Draws point in the diagram.

Question 5

in terms of plt.plot, what goes first, x or y axis?

Where is the x axis located?

Where is the y axis located?

Answer 5

x goes first:
plt.plot(x, y)

x is horizontal
y is vertical

Question 6

Draw a line diagram

x axis - start from 1 and go up to 8

y axis - start from 3 and go up to 10

Answer 6

import matplotlib.pyplot as plt
import numpy as np

xpoints = np.array([1, 8])
ypoints = np.array([3, 10])

plt.plot(xpoints, ypoints)

plt.show()

Question 7

Via diagram, mark two points:
1, 3
8, 10

remember that the x axis goes first

Answer 7

import matplotlib.pyplot as plt
import numpy as np

xpoints = np.array([1, 8])
ypoints = np.array([3, 10])

plt.plot(xpoints, ypoints,)

plt.show()

Question 8

Now create a line diagram that goes between the following points:

1,3
2,8
6,1
8,10

Answer 8

import matplotlib.pyplot as plt
import numpy as np

xpoints = np.array([1, 2, 6, 8])
ypoints = np.array([3, 8, 1, 10])

plt.plot(xpoints, ypoints)
plt.show()

Question 9

What happens if we only have the following ypoints and no x points defined:

ypoints = np.array([3, 8, 1, 10, 5, 7])

Answer 9

x will start from 1 and go to the higher depending on y

Question 10

Create a line diagram, but add a point to each peak and valley of the line, next add a star

Answer 10

import matplotlib.pyplot as plt
import numpy as np

ypoints = np.array([3, 8, 1, 10])

plt.plot(ypoints, marker = ‘o’)
plt.show()

to add a star:
marker = ‘*’

Question 11

Explain format string notation and then use it

Set your marker to be the size of 20
Set the outline of the marker to red
If you weren’t using fsn, how would you change the inner color of your marker?

Answer 11

Format String Notation is used to specify your marker on the graph.

It is in the structure of ‘marker|line|color.
Take the below for instance:

import matplotlib.pyplot as plt
import numpy as np

ypoints = np.array([3, 8, 1, 10])

plt.plot(ypoints, ‘o:r’, marker = ‘0’, ms = 20, mec = ‘r’)
plt.show()

o means you want a circle as the marker
: means you want the line to be dotted
r means you want the color to be red

you can also have the line be:
- solid
: dotted
– dashed
-. dashed dotted

mfc = ‘r’

Question 12

Change the line color to red
The width of the line to 20.5

Answer 12

plt.plot(ypoints, color = ‘r’, lw = ‘20.5’)

Question 13

Create two lines in the same graph

Answer 13

import matplotlib.pyplot as plt
import numpy as np

y1 = np.array([3, 8, 1, 10])
y2 = np.array([6, 2, 7, 11])

plt.plot(y1)
plt.plot(y2)

plt.show()

or

x1 = np.array([0, 1, 2, 3])
y1 = np.array([3, 8, 1, 10])
x2 = np.array([0, 1, 2, 3])
y2 = np.array([6, 2, 7, 11])

plt.plot(x1, y1, x2, y2)
plt.show()

Question 14

Create a graph where the x axis is called ‘Average pulse’
and the y axis is called ‘Calorie Burnage’
Give the graph a name called ‘Doctor shit’

Put the text in ‘serif’, the color as ‘blue’ and a size of 20

Position the Name of the graph to the left

Answer 14

import numpy as np
import matplotlib.pyplot as plt

x = np.array([80, 85, 90, 95, 100, 105, 110, 115, 120, 125])
y = np.array([240, 250, 260, 270, 280, 290, 300, 310, 320, 330])

font1 = {‘family’: ‘serif’, ‘color’:’blue’, ‘size’:20}
plt.plot(x, y)

plt.title(“Doctor Shit”, fontdict = font1, loc = ‘left’)
plt.xlabel(“Average Pulse”, fontdict = font1)
plt.ylabel(“Calorie Burnage” fontdict= font1)

plt.show()

Question 15

Create two diagrams and give them a title

Answer 15

plot 1:

import matplotlib.pyplot as plt
import numpy as np

x = np.array([0, 1, 2, 3])
y = np.array([3, 8, 1, 10])

Number of the plot is denoted by the last ‘1’
This figure has 1 row and 2 columns
plt.subplot(1, 2, 1)
plt.plot(x,y)
plt.title(‘SALES’)

x = np.array([0, 1, 2, 3])
y = np.array([10, 20, 30, 40])

Number of the plot is denoted by the last ‘2’
This plot has 1 row and 2 columns
plt.subplot(1, 2, 2)
plt.plot(x,y)
plt.title(‘INCOME’)
plt.show()

Question 16

Create two diagrams, give them both a name and then give a main title

Answer 16

plot 1:

import matplotlib.pyplot as plt
import numpy as np

x = np.array([0, 1, 2, 3])
y = np.array([3, 8, 1, 10])

plt.subplot(1, 2, 1)
plt.plot(x,y)
plt.title(“SALES”)

x = np.array([0, 1, 2, 3])
y = np.array([10, 20, 30, 40])

plt.subplot(1, 2, 2)
plt.plot(x,y)
plt.title(“INCOME”)

plt.suptitle(“MY SHOP”)
plt.show()

Question 17

Let’s compare two sets of data in a single diagram.

You can put whatever you want in them, but they can’t have lines, must only be markers, and have different colors that represent each respective data set

Answer 17

day one, the age and speed of 13 cars:

import matplotlib.pyplot as plt
import numpy as np

x = np.array([5,7,8,7,2,17,2,9,4,11,12,9,6])
y = np.array([99,86,87,88,111,86,103,87,94,78,77,85,86])
plt.scatter(x, y)

x = np.array([2,2,8,1,15,8,12,9,7,3,11,4,7,14,12])
y = np.array([100,105,84,105,90,99,90,95,94,100,79,112,91,80,85])
plt.scatter(x, y)

plt.show()

Question 18

how would you change the colors of your markers on the scatter plot?

What if you wanted to color each dot something different?

Answer 18

plt.scatter(x, y, color = ‘hotpink’)

colors = np.array([“red”,”green”,”blue”,”yellow”,”pink”,”black”,”orange”,”purple”,”beige”,”brown”,”gray”,”cyan”,”magenta”])

plt.scatter(x, y, c=colors)

Question 19

How would you change the size of the dots on your scatter plot?

Answer 19

plt.scatter(x, y, color = ‘hotpink’, size=20)

Question 20

Create a bar graph

what if we want the bars horizontal?

make the bar height 0.1
Make the bar width 0.1

Answer 20

import matplotlib.pyplot as plt
import numpy as np

x = np.array([“A”, “B”, “C”, “D”])
y = np.array([3, 8, 1, 10])

plt.bar(x,y, width = 0.1, height)
plt.show()

for horizontal:
plt.barh(x,y)

HEIGHT MIGHT ONLY BE FOR barh