I've been working on some code to solve a quadratic equation and plot it on a graph, I want to get a dot at the points where the line cuts the x-axis, and the coordinates of the points displayed below them. This is what the code does now. This is what I want it to do.
The code is as follows:
import matplotlib
matplotlib.use('TkAgg')
import matplotlib.pyplot as plt
import numpy as np
import math
def int_input(prompt):
while True:
try:
variable_name = int(input(prompt))
return variable_name
except ValueError:
print("Please enter a whole number (in digits)")
def float_input(prompt):
while True:
try:
variable_name = float(input(prompt))
return variable_name
except ValueError:
print("Please enter a numeric value (in digits)")
def yes_input(prompt):
while True:
variable_name = input(prompt).lower()
if variable_name in ["y", "yes"]:
return "yes"
elif variable_name in ["n", "no"]:
return "no"
else:
print("""Please enter either "y" or "n". """)
print("Quadratic Solver")
while True:
print("Input below the values of a, b and c from an equation that is of the form : ax² bx c = 0")
a = float_input('a: ')
b = float_input('b: ')
c = float_input('c: ')
# calculate the discriminant
d = (b ** 2) - (4 * a * c)
# find two solutions
try:
solution1 = (-b - math.sqrt(d)) / (2 * a)
except ValueError:
solution1 = "none"
try:
solution2 = (-b math.sqrt(d)) / (2 * a)
except ValueError:
solution2 = "none"
if solution1 == solution2:
if solution1 == "none":
print("There are no solutions.")
else:
print("There is one solution: x = {0}".format(solution1))
elif solution1 != solution2:
print('There are two solutions, x can be either {0} or {1}'.format(solution1, solution2))
graph = yes_input("Do you want to plot that on a graph? (y/n): ")
if graph == "yes":
x = np.linspace(-6, 6, 50)
fig = plt.figure(figsize=(7, 4))
y4 = a * x ** 2 b * x c
plt.plot(x, y4, 'g:', label='Degree 2')
# Add features to our figure
plt.legend()
plt.grid(True, linestyle=':')
plt.xlim([-6, 6])
plt.ylim([-4, 4])
plt.title(f'A graph of {a}x² {b}x {c} = 0')
plt.xlabel('x-axis')
plt.ylabel('y-axis')
plt.get_current_fig_manager().window.wm_geometry(" 0 0")
fig.canvas.manager.window.attributes('-topmost', 1)
# Show plot
plt.show()
new_question = yes_input('New question? (y/n): ')
if new_question == "no":
break
I'm on a windows OS and am using IntelliJ IDEA to edit my python code.
CodePudding user response：
To add dots to your graph of a quadratic equation, you can use the plt.plot function with circles markers, and use plt.text to print the coordinates of your dots.
Have a look at my solution based on your code. It's not the cleanest, but it is easily understandable (line 86-96).
import matplotlib
matplotlib.use('TkAgg')
import matplotlib.pyplot as plt
import numpy as np
import math
def int_input(prompt):
while True:
try:
variable_name = int(input(prompt))
return variable_name
except ValueError:
print("Please enter a whole number (in digits)")
def float_input(prompt):
while True:
try:
variable_name = float(input(prompt))
return variable_name
except ValueError:
print("Please enter a numeric value (in digits)")
def yes_input(prompt):
while True:
variable_name = input(prompt).lower()
if variable_name in ["y", "yes"]:
return "yes"
elif variable_name in ["n", "no"]:
return "no"
else:
print("""Please enter either "y" or "n". """)
print("Quadratic Solver")
while True:
print("Input below the values of a, b and c from an equation that is of the form : ax² bx c = 0")
a = float_input('a: ')
b = float_input('b: ')
c = float_input('c: ')
# calculate the discriminant
d = (b ** 2) - (4 * a * c)
# find two solutions
try:
solution1 = (-b - math.sqrt(d)) / (2 * a)
except ValueError:
solution1 = "none"
try:
solution2 = (-b math.sqrt(d)) / (2 * a)
except ValueError:
solution2 = "none"
if solution1 == solution2:
if solution1 == "none":
print("There are no solutions.")
else:
print("There is one solution: x = {0}".format(solution1))
elif solution1 != solution2:
print('There are two solutions, x can be either {0} or {1}'.format(solution1, solution2))
graph = yes_input("Do you want to plot that on a graph? (y/n): ")
if graph == "yes":
x = np.linspace(-6, 6, 50)
fig = plt.figure(figsize=(7, 4))
y4 = a * x ** 2 b * x c
plt.plot(x, y4, 'g:', label='Degree 2')
# Add features to our figure
plt.legend()
plt.grid(True, linestyle=':')
plt.xlim([-6, 6])
plt.ylim([-4, 4])
# Add dots
offset = 0.3
if solution1 == solution2:
if solution1 != "none":
plt.plot(solution1, 0 , marker="o", markersize=10, color="black", linestyle="None")
plt.text(solution1, 0-offset, f'({solution1}, {0})', ha='center', va='center')
elif solution1 != solution2:
plt.plot([solution1, solution2], [0, 0], marker="o", markersize=10, color="black", linestyle="None")
plt.text(solution1, 0-offset, f'({solution1}, {0})', ha='center', va='center')
plt.text(solution2, 0-offset, f'({solution2}, {0})', ha='center', va='center')
plt.title(f'A graph of {a}x² {b}x {c} = 0')
plt.xlabel('x-axis')
plt.ylabel('y-axis')
plt.get_current_fig_manager().window.wm_geometry(" 0 0")
fig.canvas.manager.window.attributes('-topmost', 1)
# Show plot
plt.show()
new_question = yes_input('New question? (y/n): ')
if new_question == "no":
break