Description

Lab Assignment #1: Python Practice
Guideline: Follow the format in LabAssignment1_report_sample.pdf to do the following exercises. Part I exercises only need results. Part II exercises need both results and comments. Convert the report to one pdf file and submit it to Camino.
Online tutorial: https://docs.python.org/3/
Part I
Exercise 1: Numbers
Run the following in python shell.
>>> a=123+222 # integer addition
>>> print(a)
>>> b = 1.5*4 # floating-point multiplication
>>> print(b)
>>> c=2**10 # 2 to the power 10
>>> print(c)
>>> import math
>>> print(math.pi)
>>> print(math.sqrt(36))
>>> import random
>>> a=random.random()
>>> print(‘a=’, a)
>>> b = random.choice([1,2,3,4])
>>> print(‘b=’, b)

Exercise 2: Strings
Run the following in python shell.
>>> S=’Spam’ # make a 4-character string, and assign it to a name
>>> len(S) # Length
>>> S[0] # the 1st item in S, indexing by zero-based position
>>> S[1] # the 2nd item from the left
>>> S[-1] # the last item from the end in S
>>> S[-2] # the second-to-last item from the end
>>> S[len(S)-1]
>>> S[1:3] # Slice of S from offsets 1 through 2 (not 3)
>>> S = ‘z’ + S[1:]
>>> S

Exercise 3: Lists
Run the following in python shell.
>>> L=[123, ‘spam’, 1.23] # A list of three different-type objects
>>> len(L) # number of items in the list
>>> L[0]
>>> L[:-1] # Slicing a list returns a new list
>>> L+[4,5,6] # contact/repeat make new lists too
>>> L*2 # repeat
>>> L # we are not changing the original list
>>> M = [‘bb’, ‘aa’, ‘cc’]
>>> M.sort()
>>> M
>>> M.reverse()
>>> M
>>> M = [[1,2,3], [4,5,6], [7,8,9]] # a list that contains three other lists, 3×3 matrix
>>> M[1] # get row 2
>>> M[1][2] # get row 2, then get item 3 within the row
>>> diag = [M[i][i] for i in [0, 1, 2]] >>> diag
>>> doubles = [c * 2 for c in ‘spam’]
>>> doubles
>>> list(range(4)) # 0..3 (list() required in 3.X)
>>> list(range(−6, 7, 2)) # −6 to +6 by 2 (need list() in 3.X)
>>> [[x ** 2, x **
3] for x in range(4)] # Multiple values, “if” filters >>> [[x, x/2, x * 2] for x in range(−6, 7, 2) if x > 0]

Exercise 4: Linear Algebra
4.1. Write a NumPy program to compute the multiplication of the following two matrixes, using numpy.dot and numpy.matmul, and print the results.
p = [[1, 0], [0, 1], [1,1]] q = [[1, 2], [3, 4]]
4.2 Write a NumPy program to find the L2-norm of vector v=numpy.arange(7) and matrix numpy.matrix(‘1, 2; 3, 4’). Print the results.
Note: the L2-norm of a vector 𝐯 = [v1, v2, . . . , vN] is defined as:

‖𝐯‖2 ≜ √v12 + v22+. . . +vN2
4.3 Write a NumPy program to compute the inverse of matrix m = np.array([[1,2],[3,4]]).

Exercise 5: Tuples
Run the following in python shell.
>>> T = (1, 2, 3, 4) # A 4-item tuple
>>> len(T)
 # Length
>> T + (5, 6)
 # Concatenation
>>> T[0] # Indexing, slicing, and more
>>> T.index(4) # Tuple methods: 4 appears at offset 3
>>> T.count(4) # 4 appears once
>>> T[0] = 2 # Tuples are immutable
…error text omitted…
TypeError: ‘tuple’ object does not support item assignment
>>> T = (2,) + T[1:] # Make a new tuple for a new value
>>> T
>>> T = ‘spam’, 3.0, [11, 22, 33]
>>> T[1]
>>> T[2][1]
Exercise 6: if Tests and Syntax Rules
Create a file test_if.py that contains the following lines, then run the module, show the results in the lab report. x =1
if x:
y= 2 if y:
print(‘block2’) print(‘block1’) print(‘block0’)

choice = ‘ham’
if choice == ‘spam’: # the equivalent if statement print(1.25) elif choice == ‘ham’:
print(1.99) elif choice == ‘eggs’:
print(0.99) elif choice == ‘bacon’:
print(1.10) else:
print(‘Bad choice’)

Exercise 7: while and for Loops
Run the following in python shell.
>>> x = ‘spam’
>>> while x: # while x is not empty print(x,end=’ ‘) # in 2.X use print x x=x[1:] # strip first character off x

>>> a=0; b=10
>>> while a<b: # one way to code counter loops print(a,end=’ ‘)
a+=1 # or, a = a + 1

>>> x=10
>>> while x:
x=x-1 # or, x -=1
if x%2 !=0: continue # odd? – skip print print(x, end=’ ‘)

>>> for x in [“spam”, “eggs”, “ham”]:
print(x, end=’ ‘)

>>> sum = 0
>>> for x in [1, 2, 3, 4]:
sum = sum + x
>>> sum

>>> prod = 1
>>> for item in [1,2,3,4]: prod*= item
>>> prod
Part II
Exercise 8: Functions

Create fun1.py and fun2.py as the following, run them, show the results, and explain what each function does (and the results) in your own words.

fun1.py

def times(x,y): # create and assign function return x*y # Body executed when called

a = times(2,4) b = times(‘Ok’, 4) # Functions are “typeless”

print(a,’ ’, b)

s1 = “SPAM”
s2 = “SCAM”
result1 = intersect(s1, s2) print(result1)

result2 = intersect([1, 2, 3], (1, 4)) # mixed type: list & tuple print(result2)

Exercise 9: modules

Create module.py, test1_module.py, test2_module.py, and test3_module.py as the following, run test1_module.py, test2_module, and test3_module.py, show the results, and explain your findings.

module.py

a = 10 b = 20

def adder(x, y): # module attribute
z = x + y
return z

def multiplier(x, y):
z = x*y
return z

test1_module.py

import module # Get module as a whole result = module.adder(module.a, module.b) # Qualify to get names print(result)

test2_module.py

c = 5 d = 10
from module import adder # Copy out an attribute result = adder(c, d) # No need to qualify name print(result)

from module import a, b, multiplier # Copy out multiple attributes result = multiplier(a, b) print(result)
test3_module.py

from module import * # Copy out all attributes result1 = adder(a, b) result2 = multiplier(a, b)
print(result1, ‘ ‘, result2)

Exercise 10: built-in attribute of modules

Each module has a built-in attribute: __name__.
If the file is being run as a top-level program file, __name__ is set to the string “__main__” when it starts.
If the file is being imported, __name__ is instead set to the module’s name as known by its clients.
Read the following example:

runme.py

def tester() print “It’s Christmas in Heaven…”

if __name__==’__main__’: # Only when run
tester() # Not when imported

(1) Create minmax.py as the following, run it, show the results, and explain what this .py file does.

def minmax(test,array): res = array[0] for arg in array[1:]: if test(arg, res):
res = arg
return res

def lessthan(x,y): return x<y
def grtrthan(x,y): return x>y

print(minmax(lessthan, [4,2,1,5,6,3])) # self-test code print(minmax(grtrthan, [4,2,1,5,6,3]))

(2) Create minimax2.py as the following, run it, show the results, and explain what this .py file does.

def minmax(test,array): res = array[0] for arg in array[1:]: if test(arg, res):
res = arg
return res

def lessthan(x,y): return x<y
def grtrthan(x,y): return x>y

if __name__ == ‘__main__’:
print(minmax(lessthan, [4,2,1,5,6,3])) # self-test code print(minmax(grtrthan, [4,2,1,5,6,3]))

(3) From python shell, execute the following two commands, show the results, and explain your findings.

import minmax
import minmax2

Exercise 11: Object-Oriented Programming and Classes

(1) Create class1.py as the following, run it, show the results, and explain what the code does.

class FirstClass: # define a class object def setdata(self,value1, value2): # Define class’s methods self.data1=value1 # self is the instance self.data2=value2 def display(self):
print(self.data1, ‘ ‘, self.data2, ‘ ‘)

x=FirstClass() # make one instance

x.setdata(“King Arthur”,-5) # Call methods: self is x
x.display()

x.data1=”QQ”
x.data2=-3
x.display()

x.anothername=”spam”
x.display() print(x.anothername)

(2) Class Inheritance: create class2.py as the following, run it, show the results, and explain what the code does.

class FirstClass: def setdata(self,value1, value2):
self.data1=value1 self.data2=value2 def display(self):
print(self.data1, ‘ ‘, self.data2, ‘ ‘)

class SecondClass(FirstClass): # inherits setdata and display
def adder(self,val1,val2): # create adder
a=val1+val2 print(a)

z=SecondClass() # make one instance z.setdata(10,20)
z.display()
z.adder(-5,-10)

(3) The constructor method: create class3.py as the following, run it, show the results, and explain what the code does.

class Person:
def __init__(self, name, jobs, age=None): # __init__ is the constructor method of a class
#it is to initialize the object’s states self.name=name self.jobs=jobs
self.age=age

def info(self): # another method of the class return (self.name, self.jobs)

rec1 = Person(‘Bob’, [‘dev’, ‘mgr’], 40.5)
rec2 = Person(‘Sue’, [‘dev’, ‘cto’])

print(rec1.jobs)
print(rec2.info())

(4) Classes are attributes in modules: create class_as_module.py as the following, run it, show the results, and explain what the code does.

class_as_module.py

import class3

rec3 = class3.Person(‘Jane’, [‘dev’, ‘mgr’], 30)

print(rec3.age) print(rec3.info()) from class3 import Person

rec4 = Person(‘Mike’, [‘dev’, ‘mgr’], 35) print(rec4.age) print(rec4.info())