Semester 06 (Spring 2019)
Lab 01: Python Programming 1
Introduction to :
1. Java Versus Python (Side by Side Comparison)
2. Control Structures(if, if else, switch, for, while and do while) 3. Arrays(one, two and three dimensional)
1. Java Versus Python
1. Hello World
Java Python
public class HelloWorld{
public static void main(String[] args){ System.out.println("Hello world!");} }
print("Hello world!")
2. Statements
Java Python
Statements in Java always end with a semicolon (;). It is possible for a statement to run over more than one line, or to have multiple statements on a single line. Examples: this is a statement;
this is another statement; this is a long statement that extends over more than one line;
Python is line-oriented: statements end at the end of a line unless the line break is explicitly escaped with \. There is no way to put more than one statement on a single line. Examples:
this is a statement this is another statement this is a long statement that\ extends over more than one line
3. Use of Variables
Java Python
Java is statically typed: int someVariable; int someVariable = 42;
• A variable that has been declared to be of a particular type may not be assigned a value of a different type.
Python is dynamically typed: someVariable = 42
• A variable that has been assigned a value of a given type may later be assigned a value of a different type.
Java has two kinds of data types: primitive types and reference types.
• byte - 8-bit integers • short - 16-bit integers • int - 32-bit integers • long - 64-bit integers • float - 32-bit real numbers. • double - 32-bit real numbers. • boolean - (false and true). • char - a single character.
someVariable = 'Hello, world'
Python supports the following built-in data types:
• Plain integers (32-bit integers).
• Long integers (memory size of the machine) • Booleans (False and True).
• Real numbers. • Complex numbers.
4. Input From Console
Java Python
import java.util.Scanner; public class HelloWorld{
static public void main(String[] args){ Scanner input = new Scanner(System.in); System.out.println("Enter your Name"); String name = input.nextLine();
System.out.println("Enter your age"); int age = input.nextInt();
} }
name = input("Enter your Name") age = int(input("Enter your age")
price = float(input("Enter item price")
4. Comments
Java Python
Single Line
// This is an end of // line comment
// (on three lines).
Multiline /*
This is a multi-line comment.
*/
Single Line
# This is an end of # line comment # (on three lines).
Multiline """
This is a docstring or multi-line comment. """
5.Arithmatic Operators
Java Python
Operato r
Meaning Example
+ Add x + y
+2 - Subtract x - y
-2 * Multiply x * y
Operato r
Meaning Example
+ Add x + y
+2
- Subtract x - y
-2
/ Divide x / y
% Modulus x % y
(remainder of x/y)
/ Divide x / y
% Modulus x % y
(remainder of x/y)
// Floor division x // y
** Exponent x**y (x to the power y)
6. Comparison Operators
Java Python
Operato r
Meaning Exampl e > Greater that x > y < Less that x < y
== Equal to x == y
!= Not equal to x != y >= Greater than or
equal
x >= y <= Less than or equal
to x <= y
Operato r
Meaning Exampl e > Greater that x > y
< Less that x < y
== Equal to x == y
!= Not equal to x != y
>= Greater than or equal x >= y <= Less than or equal to x <= y
7. Logical Operators
Java Python
Operato r
Meaning Exampl e && True if both the
operands are true
x && y || True if either of the
operands is true
x || y ! True if operand is
false (complements the operand) ! x Operato r Meaning Exampl e and True if both the
operands are true
x and y or True if either of the
operands is true
x or y not True if operand is
false (complements the operand)
not x
8. Assignment Operators
Java Python
Operato r
Example Equivatent to
= x = 5 x = 5
+= x += 5 x = x + 5 -= x -= 5 x = x - 5 *= x *= 5 x = x * 5 /= x /= 5 x = x / 5 %= x %= 5 x = x % 5
Operato r
Example Equivatent to
= x = 5 x = 5
+= x += 5 x = x + 5
-= x -= 5 x = x - 5
*= x *= 5 x = x * 5
/= x /= 5 x = x / 5
- -
-- -
-&= x &= 5 x = x & 5 |= x |= 5 x = x | 5 ^= x ^= 5 x = x ^ 5 >>= x >>= 5 x = x >> 5 <<= x <<= 5 x = x << 5
//= x //= 5 x = x // 5
**= x **= 5 x = x ** 5
&= x &= 5 x = x & 5
|= x |= 5 x = x | 5
^= x ^= 5 x = x ^ 5
>>= x >>= 5 x = x >> 5 <<= x <<= 5 x = x << 5
9. Conditional Statements
Java Python
IF-Statement if (x < 0) {
something; }
IF-Else Statement if (x < 0) { something; } else {
somethingdifferent; }
IF-Else If Statement if (x < 0) {
something;
} elseif (x > 0) { somethingdifferent; } else {
yetanother thing; }
IF-Statement if x < 0:
something
IF-Else Statement if x < 0:
something else:
somethingdifferent
IF-elif Statement if x < 0:
something elifx > 0:
somethingdifferent else:
yetanother thing
10. Switch Statement
Java Python
switch(expression){
case 1: dosomething();break; case 2: dosomething();break; .
.
default: dosomething() }
Not availabe in python.
11. Loops
Java Python
For Loop
for(int i = 1; i < 10; i ++){ something;
For Loop
}
(i takes on values 1, 2, 3, 4, 5, 6, 7, 8, 9)
for (int i = 1; i < 10; i += 2){ System.out.print(i);
}
(i takes on values 1, 3, 5, 7, 9) While Loop
int x = 5
while (x > 0) {
System.out.print(x); x-=1;
}
Do-While int x = 5 do{
System.out.print(x); x-=1;
}while (x > 0)
something2
(i takes on values 1, 2, 3, 4, 5, 6, 7, 8, 9) for i in range(1, 10, 2):
print(i)
(i takes on values 1, 3, 5, 7, 9) While Loop
x = 5
while x > 0: print(x) x-=1
Do-While
Not availabe in python.
12. Arrays
Java Python
One Dimensional
int [] list = {32, 27, 64, 18}; System.out.println(list);
int [] list = new int[10]; for(int i=0;i<10;i++)
list[i]=i;
Two Dimensional
int [][]myArray = {{1,2},{3,4}};
int [][]myArray = new int[3][3];
One Dimensional
list = [32, 27, 64, 18] print(list)
list=[0 for i in range(10)] for i in range(10):
list[i]=i
Two Dimensional
myArray=[[1,2],[3,4]]
myArray=[[0 for j in range(3)] for i in range(3)]
13. String
Java Python
+
*
Concatenation
Repetition
s = 'Hello'
[i], [-i]
[m:n], [m:], [:n],
[m:n:step]
Obj.index(str )
Indexing from front or back, front index begins at 0, back index begins at -1 (or len-1)
Slicing from index m (inclusive) to n (exclusive) with an optional step size. Default m is 0, n is len-1.
Returns the index of string
s * 2 ⇒ 'HelloHello'
Char: H e l l o Index: 0 1 2 3 4 Index from right: -5 -4 -3 -2 -1
s[1] ⇒ 'e' s[-4] ⇒ 'e'
s[1:3] ⇒ 'el'
s[1:-2] ⇒
'el'
s[3:] ⇒ 'lo' s[:-2] ⇒
'Hel'
s[0:5:2] ⇒ 'Hlo'
s.index(“o”) ⇒ 4
String Operations:
Write a Java program that enters a 10-digit string as a typical U.S. telephone number. Extract the 3-digit area code, the 3-3-digit "exchange," and the remaining 4-3-digit number as separate strings, prints them, and then prints the complete telephone number in the usual form atting. A sample run might look like this:
Enter 10-digit telephonenumber: 1234567890 You entered 1234567890
The area code is 123 The exchange is 456 The number is 7890
The complete telephone number is (123)456-7890
phone = input("Enter telephone number") area = phone[0:3]
#print (area)
exchange = phone[3:6] #print (exchange)
number = phone[6:len(phone)] #print(number)
print("The complete phone number is :") print("(",area,")",exchange,"-",number)
Write a Python program that generates a random year between 1800 and 2050 and then reports whether it is a leap year. A leap year is an integer greater than 1584 that is either divisible by 400 or isdivisible by 4 but not 100. To generate an integer in the range 1800 to 2050, use
year = int(random.random()*250 + 1800
The random.random() method returns the a value betweenbetween 0 and 1. The transformation 1800 converts a number in the range the range l800 ≤ year< 2050.
import random
year = int(random.random()*250)+1800 print ("The year is :",year)
if((year % 400 == 0 or year%100 != 0) and year%4 == 0): print("That is a leap year..")
else:
print("That is not a leap year..")
3. Arrays
An example of simple array declared and initilized
list = [32, 27, 64, 18, 95, 14, 90, 70, 60, 37] print(list)
2D Array:
APython program to calculate the sum of each row, colum, left diagonal and right diagonalof a two-dimensional (2D) array of size MxM.for example:
R O W S
[0
] 1 2 3 4 5
[1
] 6 7 8 9 10
[2
] 11 12 13 14 15
[3
] 16 17 18 19 20
[4
] 21 22 23 24 25
[0 ]
[1 ]
[2 ]
[3 ]
[4 ] COLUMNS Sum of row 1: 15
Sum of row 4: 90 Sum of row 5: 115
Sum of Col 1: 55 Sum of Col 2: 60 Sum of Col 3: 65 Sum of Col 4: 70 Sum of Col 5: 75
Sum of Left Diagonal: 65 Sum of Right Diagonal: 65
import random ROWS = 5 COLUMNS = 5
matrix = [[0 for i in range(ROWS)] for j in range(COLUMNS)] #Randomly assigning values
for i in range(ROWS):
for j in range(COLUMNS):
matrix[i][j]= int(random.random()*25) #Print each row of matrix
for i in range(ROWS): print(matrix[i])
#Calculating the sum of each row for i in range(ROWS):
rowSum=0;
for j in range(COLUMNS): rowSum+=matrix[i][j]
print("Sum of Row ",(i+1)," : ",rowSum) #Calculating the sum of each column
for i in range(ROWS): colSum=0;
for j in range(COLUMNS): colSum+=matrix[j][i]
print("Sum of Column ",(i+1)," : ",colSum) #Calculating the sum of left diagonal
leftDiagonalSum=0; for i in range (ROWS):
leftDiagonalSum+=matrix[i][i];
print("Sum of left diagonal : ",leftDiagonalSum); #Calculating the sum of right diagonal
rightDiagonalSum=0; for i in range(ROWS):
rightDiagonalSum+=matrix[i][(ROW-1)-i]
print("Sum of left diagonal : ",rightDiagonalSum);
Exercises
Write a Python program that needs to ask the use for her or his address. The application takes as input this address, parses the address and replies to the user with house number, street number, area and city.
A sample run is given below for your convenience. User input is shown in bold:
Please enter your address: House D 13 Street 14 NHS Karachi House Number: D 13
Street Number: Street 14 Area: Naval Housing Scheme City: Karachi
Exercise 2 (Roman.py)
Write a program that converts a positive integer into the Roman number system. The Roman number system has digits I (1), V (5), X (10), L (50), C(100), D(500) and M(1000). Numbers up to 3999 are formed according to the following rules:
a) As in the decimal system, the thousands, hundreds, tens and ones are expressed separately. b) The numbers 1 to 9 are expressed as:
1 I 6 VI
2 II 7 VII
3 III 8 VIII
4 IV 9 IX
5 V
(An I preceding a V or X is subtracted from the value, and there cannot be more than three I’s in a row.) c) Tens and hundreds are done the same way, except that the letters X,L,C, andC,D,Mare used
instead of I, V, X,respectively.
Your program should take an input, such as 1978, and convert it to Roman numerals, MCMLXXVIII.
Exercise 3 (BMICalculator.py)
Write a program that calculates students percentage and categorizes it into a grade (A,B,C,D,F) on the basis of his/her marks:
Total marks (500)
Grad e
Above 450 A
450-400 B
399-350 C
349-300 D
Prompt the user to enter marks out of 500, the program should calculate the percentage and assign the grade.
[SAMPLE RUN]
Enter your total marks out of 500: 400 Percentage= 80%
Grade= B
Exercise 4 (Arithmatic.py)
Write a python program to compute quotient and remainder of a number without using division ('/') operator and modulo ('%') operator.
Exercise 5 (BloodType.py)
Blood types are important for blood transfusion. The blood types must be matched since if not matched properly, the recipient’s blood can form clots and these can lead to heart attacks, embolisms and strokes.
The following table summarize blood groups compatibility: Donor Recipien
t
O
-O +
A
-A +
B
-B +
AB
-AB +
O- x
O+ x x
A- x x
A+ x x x x
B- x x
B+ x x x x
AB- x x x x
AB+ x x x x x x x x
[Sample Run]
Enter Blood type: O+ Can Receive from: O-, O+
Can Donate to: O+, A+, B+, AB+
Do you want to continue for another value (y/n)? y Enter Blood type: A+
Can Receive from: O-, O+, A-, A+ Can Donate to: A+, AB+
Do you want to continue for another value (y/n)? n
Exercise 6 (Occurrances.py)
Write a program to take an array and find the number of occurrences each number had. The output should be something like this:
NumberOccurrences
0 0 2 2 2 3 3 3 4 4
21 21 21 21 21 29 29 29 29 29 37 37 37 37 37 42 42 42 42 42 50 50
NOTE:Sort the array elements first and then calculate the frequency of each element. Use for-loop to calcute the frequency of each element.
Exercise 7 (Histogram.py)
Given the following array, display its data graphically by plotting each numeric value as a bar of dollars ($) as shown in the diagram.
array = [10, 19, 5, 1, 7, 14, 0, 7, 5]
Element Value Histogram
0 10 $$$$$$$$$$
1 19 $$$$$$$$$$$$$$$$$$$
2 5 $$$$$
3 1 $
4 7 $$$$$$$
5 14 $$$$$$$$$$$$$$
7 7 $$$$$$$
8 5 $$$$$
Exercise 8 (Transpose.py)
Suppose you have the following matrix:
2 0 4 2 6 3 9 9 1 0 4 1 7 1 2 3 7 4 2 2 2 7 1 6 1 5 8 7 4 1
Design then implement a Java program that will produce its transpose and print it along with the original one.
HINT:
The transpose of matrix A = [aij] is the mxn matrix AT defined by AT = [aji] So, the transpose of the matrix above is:
2 9 7 2 1 0 9 1 2 5 4 1 2 2 8 2 0 3 7 7 6 4 7 1 4 3 1 4 6 1
Exercise 9 (MatricesMultiplication.py)
Suppose you have the following matrices:
Exercise 10 (Scores.py)
Write a program that calculates the total score for students in a class. Suppose the scores are stored in a three-dimensional array named scores. The first index in scores refers to a student, the second refers to an exam, and the third refers to the part of the exam. Suppose there are 7 students, 5 exams, and each exam has two parts--the multiple-choice part and the programming part. So, scores[i][j][0] represents the score on the multiple-choice part for the i’s student on the j’s exam. Your program displays the total score for each student.
