Wright State University Lake Campus/2019-1/Python

Wright State University Lake Campus/2019-1/Matlab

Importing the math module

# Python imports things, like "math"
import math
print("math.pi", math.pi)
#print("this crashes: print(pi)",pi)
from math import pi, sin, cos
print(pi,sin(pi/4),cos(pi/4))

Matrices

This is why most Lake students prefer MatLab to Python (though with modules Python would certainly improve upon the following...)

m=[[1,2,3],
   [4,5,6],
   [7,8,9]]

def transposeMatrix(m):
    return map(list,zip(*m))

def getMatrixMinor(m,i,j):
    return [row[:j] + row[j+1:] for row in (m[:i]+m[i+1:])]

def getMatrixDeternminant(m):
    #base case for 2x2 matrix
    if len(m) == 2:
        return m[0][0]*m[1][1]-m[0][1]*m[1][0]

    determinant = 0
    for c in range(len(m)):
        determinant += ((-1)**c)*m[0][c]*getMatrixDeternminant(getMatrixMinor(m,0,c))
    return determinant

def getMatrixInverse(m):
    determinant = getMatrixDeternminant(m)
    #special case for 2x2 matrix:
    if len(m) == 2:
        return [[m[1][1]/determinant, -1*m[0][1]/determinant],
                [-1*m[1][0]/determinant, m[0][0]/determinant]]

    #find matrix of cofactors
    cofactors = []
    for r in range(len(m)):
        cofactorRow = []
        for c in range(len(m)):
            minor = getMatrixMinor(m,r,c)
            cofactorRow.append(((-1)**(r+c)) * getMatrixDeternminant(minor))
        cofactors.append(cofactorRow)
    cofactors = transposeMatrix(cofactors)
    for r in range(len(cofactors)):
        for c in range(len(cofactors)):
            cofactors[r][c] = cofactors[r][c]/determinant
    return cofactors
###################################
# Program to multiply two matrices using nested loops

# 3x3 matrix
X = [[12,7,3],
    [4 ,5,6],
    [7 ,8,9]]
# 3x4 matrix
Y = [[5,8,1,2],
    [6,7,3,0],
    [4,5,9,1]]
# result is 3x4
result = [[0,0,0,0],
         [0,0,0,0],
         [0,0,0,0]]

print('printing product')
# iterate through rows of X
for i in range(len(X)):
   # iterate through columns of Y
   for j in range(len(Y[0])):
       # iterate through rows of Y
       for k in range(len(Y)):
           result[i][j] += X[i][k] * Y[k][j]

for r in result:
   print(r)
#####################################

myOut=transposeMatrix(m)
print('transpose\n',list(myOut))

GUI tkinter

Feb 27

https://docs.python.org/3.6/library/tkinter.html I need to make a gui to facilitate the writing of tests. Now I have a laborious system that uses a csv file that I modify using Excel.

#I hound this hard to understand.  It refers to the following code:
import tkinter as tk

class Application(tk.Frame):
    def __init__(self, master=None):
        super().__init__(master)
        self.master = master
        self.pack()
        self.create_widgets()

    def create_widgets(self):
        self.hi_there = tk.Button(self)
        self.hi_there["text"] = "Hello World\n(click me)"
        self.hi_there["command"] = self.say_hi
        self.hi_there.pack(side="top")

        self.quit = tk.Button(self, text="QUIT", fg="red",
                              command=self.master.destroy)
        self.quit.pack(side="bottom")

    def say_hi(self):
        print("hi there, everyone!")

root = tk.Tk()
app = Application(master=root)
app.mainloop()

# A better intro might be at:
#https://python-textbok.readthedocs.io/en/1.0/Introduction_to_GUI_Programming.html

28 February 2019

Promising tutorial here

import tkinter as tk

root = tk.Tk()
tk.Label(root, 
		 text='''Does anybody in Phy1060 want
to learn how to make a GUI using Python?''',
		 fg = "red",
		 font = "Times").pack()
tk.Label(root, 
		 text="GUI is short for",
		 fg = "light green",
		 bg = "dark green",
		 font = "Helvetica 16 bold italic").pack()
tk.Label(root, 
		 text="Graphical User Interface",
		 fg = "blue",
		 bg = "yellow",
		 font = "Verdana 10 bold").pack()

tk.Label(root, 
		 text='''
See https://www.python-course.eu/python_tkinter.php

A GUI can be used to allow teachers
to use Quizbank quizzes without any knowledge of Python
or advanced programing of any kind.  It should be possible
to post questions from a bank by just clicking on buttons.

I wonder if I can do this? Yes, I can skip lines on this GUI

And it is not hard to count seconds:''',
		 fg = "black",
		 bg = "white",
		 font = "Verdana 10").pack()

counter = 0 
def counter_label(label):
  def count():
    global counter
    counter += 1
    label.config(text=str(counter))
    label.after(1000, count)
  count()
  
label = tk.Label(root, fg="green")
label.pack()
counter_label(label)
button = tk.Button(root, text='Stop', width=25, command=root.destroy)
button.pack()
		 

root.mainloop()

Hovering

#https://stackoverflow.com/questions/20399243
import tkinter as tk

class Example(tk.Frame):
    def __init__(self, *args, **kwargs):
        tk.Frame.__init__(self, *args, **kwargs)
        self.l1 = tk.Label(self, text="Hover over me")
        self.l2 = tk.Label(self, text="", width=40)
        self.l1.pack(side="top")
        self.l2.pack(side="top", fill="x")

        self.l1.bind("<Enter>", self.on_enter)
        self.l1.bind("<Leave>", self.on_leave)

    def on_enter(self, event):
        self.l2.configure(text="Hello world")

    def on_leave(self, enter):
        self.l2.configure(text="")

if __name__ == "__main__":
    root = tk.Tk()
    Example(root).pack(side="top", fill="both", expand="true")
    root.mainloop()