diff --git a/archive.html b/archive.html index 15bd665..30581e1 100644 --- a/archive.html +++ b/archive.html @@ -23,9 +23,9 @@

RMK Coding Club

@@ -34,6 +34,23 @@

RMK Coding Club

diff --git a/presentations.html b/presentations.html index 7ddfb79..d8735b4 100644 --- a/presentations.html +++ b/presentations.html @@ -23,9 +23,9 @@

RMK Coding Club

diff --git a/python.html b/python.html new file mode 100644 index 0000000..da22f9f --- /dev/null +++ b/python.html @@ -0,0 +1,1814 @@ + + + + +Python-Workshop + + + + + + + + + + + + + + + + + + + + +
+
+ +
+
+
+
+
+

Workshop on the basics of Python

+
+
+
+
+
+
+
+
+
    +
  • Python is an interpreted, high level language.
    • +
  • Interpreted - No compilation.
    • +
  • Extremely powerful and easy to understand.
    • +
  • So many features - The Swiss knife of programming.
    • +
  • Used by Google, Youtube, NASA, AI companies, etc.
    • +
+ +
+
+
+
+
+
In [64]:
+
+
+
print "Hello, CSE!"
+
+ +
+
+
+ +
+
+ + +
+
+
Hello, CSE!
+
+
+
+ +
+
+ +
+
+
+
In [62]:
+
+
+
a = 10
+b = 5
+print a, b
+
+a, b = b, a
+print a, b
+
+ +
+
+
+ +
+
+ + +
+
+
10 5
+5 10
+
+
+
+ +
+
+ +
+
+
+
+
+
+

But what about int n??

+
+
+
+
+
+
+
+
+

No need to specify data types. Automatically recognises them

+ +
+
+
+
+
+
In [65]:
+
+
+
n = 10
+
+s = "Department of CSE"
+
+marks = [
+    90, 82, 99, 97
+]
+
+marksTuple = (
+    90, 82
+)
+
+regNos = {
+    95: "Siva",
+    116: "Vignesh",
+    85: "Sagar"
+}
+
+print type(n)
+print type(s)
+print type(marks)
+print type(regNos)
+
+ +
+
+
+ +
+
+ + +
+
+
<type 'int'>
+<type 'str'>
+<type 'list'>
+<type 'dict'>
+
+
+
+ +
+
+ +
+
+
+
+
+
+

int

Use raw_input() for getting inputs.

+

eg.

+ +
+
+
+
+
+
In [66]:
+
+
+
testNo1 = raw_input()
+testNo2 = raw_input()
+
+print testNo1 + testNo2
+
+ +
+
+
+ +
+
+ + +
+
+
1
+2
+12
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Why ??

+
+
+
+
+
+
+
+
+

raw_input takes str arguments by default. Cast it to int when necessary.

+ +
+
+
+
+
+
In [67]:
+
+
+
testNo1 = int(raw_input())
+testNo2 = int(raw_input())
+
+print testNo1 + testNo2
+
+#Subtraction, Multiplication     -> One line comment
+"""
+Division, Modulo have the same   -> Multiline comment
+operators as that of other
+languages like C
+"""
+
+ +
+
+
+ +
+
+ + +
+
+
2
+3
+5
+
+
+
+ +
Out[67]:
+ + +
+
'\nDivision, Modulo have the same   -> Multiline comment\noperators as that of other\nlanguages like C\n'
+
+ +
+ +
+
+ +
+
+
+
In [69]:
+
+
+
testNo1 ** testNo2
+
+ +
+
+
+ +
+
+ + +
Out[69]:
+ + +
+
8
+
+ +
+ +
+
+ +
+
+
+
+
+
+

There is also a complex data type.

+ +
+
+
+
+
+
In [70]:
+
+
+
c1 = 3 + 5j
+c2 = 5 - 8j
+
+print type(c1)
+print c1 + c2
+print c1 - c2
+print c1 * c2
+print c1 / c2
+print c1 ** c2
+
+ +
+
+
+ +
+
+ + +
+
+
<type 'complex'>
+(8-3j)
+(-2+13j)
+(55+1j)
+(-0.280898876404+0.550561797753j)
+(-22828539.0958-11631178.0866j)
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Task

+
+
+
+
+
+
+
+
+

Can you figure out how to do 10/3 in floating point?

+ +
+
+
+
+
+
+
+
+

str

+
+
+
+
+
+
In [71]:
+
+
+
s1 = "Hello"
+s2 = "World" #can also be written as 'World'
+
+print s1 + ", " + s2 + "!"
+print len(s1)
+
+print s1*3
+
+ +
+
+
+ +
+
+ + +
+
+
Hello, World!
+5
+HelloHelloHello
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Task

+
+
+
+
+
+
+
+
+

Write a Python code to take in your name and CGPA as inputs and print "Welcome to Python, nameHere. Your CGPA is CGPAHere"

+ +
+
+
+
+
+
+
+
+ +
Welcome to Python, Siva. Your CGPA is 8.
+ +
+
+
+
+
+
+
+
+

List

+
+
+
+
+
+
+
+
+

Collection of elements. The elements can be of different data types.

+ +
+
+
+
+
+
In [73]:
+
+
+
l = [1, 2, 3]
+
+ +
+
+
+ +
+
+
+
+
+
+

To access list elements, use

+ +
+
+
+
+
+
In [74]:
+
+
+
print l[0]
+
+ +
+
+
+ +
+
+ + +
+
+
1
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Python strings are like a list of characters. So,

+ +
+
+
+
+
+
In [75]:
+
+
+
print s1[0] #Will give the first element
+
+ +
+
+
+ +
+
+ + +
+
+
H
+
+
+
+ +
+
+ +
+
+
+
+
+
+

To add an element,

+ +
+
+
+
+
+
In [76]:
+
+
+
l.append(4)
+
+print l
+
+ +
+
+
+ +
+
+ + +
+
+
[1, 2, 3, 4]
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Slicing a list - the cool part

+ +
+
+
+
+
+
In [77]:
+
+
+
dept = "Department of CSE"
+
+#Usage: list[startingIndex:endingIndex:increment]
+print dept[4:8]
+print dept[4:8:2]
+
+#Tricks
+print dept[5:len(dept)-1] #will print from 5th element to the end
+print dept[:8]            #print from the starting element to the 8th element
+print dept[::-1]          #print the list in the reverse order
+
+
+#Finding an element
+pos = dept.index("CSE")
+print "The word CSE is present at " + str(pos) + "th position"
+
+#Joining the elements of a list
+joinExample = [
+    '1', '2', '3'        #Be careful to use a list with str elements for join 
+]
+print ",".join(joinExample)
+
+ +
+
+
+ +
+
+ + +
+
+
rtme
+rm
+tment of CS
+Departme
+ESC fo tnemtrapeD
+The word CSE is present at 14th position
+1,2,3
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Using lists and str together

+
+
+
+
+
+
+
+
+

Task

+
+
+
+
+
+
In [78]:
+
+
+
sentence = "My name is Siva"
+words = sentence.split() #or sentence.split(" ")
+print words
+
+ +
+
+
+ +
+
+ + +
+
+
['My', 'name', 'is', 'Siva']
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Can you produce the following output using the list words?

+ +
Siva is name My
+

Clue: Use join.

+ +
+
+
+
+
+
+
+
+

Dictionary

+
+
+
+
+
+
In [79]:
+
+
+
dictionary = {
+    1: "one",
+    2: "two",
+    3: "three"
+}
+
+print dictionary[1]
+
+print dictionary.values()
+print dictionary.keys()
+
+ +
+
+
+ +
+
+ + +
+
+
one
+['one', 'two', 'three']
+[1, 2, 3]
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Task

Write a program that would get a number from a user between 20 and 30 and print it in words.

+

Example,

+ +
input  -> 25
+output -> twenty five
+

Clues:

+
    +
  • Use raw_input() for input. Be careful with the data type.
    • +
  • Use a dictionary for storing the corresponding words for numbers.
    • +
  • A rough, dirty approach would be like,
    • +
+ +
words = {
+   1: "one"
+   4: "four"
+}
+n = 24 #example
+print "twenty " + words[int(str(n)[1])]
+

The above solution is too dirty. Python is all about code beauty. +Try and make it beautiful.

+ +
+
+
+
+
+
+
+
+

Conditions and looping

+
+
+
+
+
+
+
+
+

Python has no braces. Indentation is used instead.

+

Also, there is no switch.

+ +
+
+
+
+
+
In [80]:
+
+
+
if(True):
+    print "Hello"
+else:
+    print "No"
+
+ +
+
+
+ +
+
+ + +
+
+
Hello
+
+
+
+ +
+
+ +
+
+
+
In [81]:
+
+
+
a = 10
+
+if(a == 1):
+    print "one"
+elif(a == 2):
+    print "two"
+else:
+    print "oops"
+
+ +
+
+
+ +
+
+ + +
+
+
oops
+
+
+
+ +
+
+ +
+
+
+
In [82]:
+
+
+
i = 10
+while(i > 0):
+    print i
+    i -=1
+
+ +
+
+
+ +
+
+ + +
+
+
10
+9
+8
+7
+6
+5
+4
+3
+2
+1
+
+
+
+ +
+
+ +
+
+
+
In [83]:
+
+
+
#usage: range(start, end, increment)
+for x in range(10):
+    print x
+
+ +
+
+
+ +
+
+ + +
+
+
0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+
+
+
+ +
+
+ +
+
+
+
In [84]:
+
+
+
a = ["one", "two", "three"]
+for x in a:
+    print x
+
+ +
+
+
+ +
+
+ + +
+
+
one
+two
+three
+
+
+
+ +
+
+ +
+
+
+
In [1]:
+
+
+
#what's the difference?
+for x in xrange(10):
+    print x
+
+ +
+
+
+ +
+
+ + +
+
+
0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+
+
+
+ +
+
+ +
+
+
+
+
+
+

List comprehension

+
+
+
+
+
+
In [85]:
+
+
+
nos = [x for x in range(20)]
+nos
+
+ +
+
+
+ +
+
+ + +
Out[85]:
+ + +
+
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
+
+ +
+ +
+
+ +
+
+
+
In [86]:
+
+
+
even = [x for x in range(20) if x%2 == 0]
+even
+
+ +
+
+
+ +
+
+ + +
Out[86]:
+ + +
+
[0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
+
+ +
+ +
+
+ +
+
+
+
In [87]:
+
+
+
strange_odd = [x+1 for x in range(20) if x%2 == 0]
+strange_odd
+
+ +
+
+
+ +
+
+ + +
Out[87]:
+ + +
+
[1, 3, 5, 7, 9, 11, 13, 15, 17, 19]
+
+ +
+ +
+
+ +
+
+
+
+
+
+

Functions

+
+
+
+
+
+
In [88]:
+
+
+
def area(side):
+    return side*side
+
+def foo(side, length=2):
+    return (side*length)
+
+print area(10)
+
+trial2 = foo(2)
+print trial2
+
+ +
+
+
+ +
+
+ + +
+
+
100
+4
+
+
+
+ +
+
+ +
+
+
+
In [89]:
+
+
+
#note the %i and %f
+
+def tax(bill):
+    """Adds 8% tax to a restaurant bill."""
+    bill *= 1.08
+    print "With tax: %f" % bill
+    return bill
+
+def tip(bill):
+    """Adds 15% tip to a restaurant bill."""
+    bill *= 1.15
+    print "With tip: %i" % bill
+    return bill
+    
+meal_cost = 100
+meal_with_tax = tax(meal_cost)
+meal_with_tip = tip(meal_with_tax)
+
+ +
+
+
+ +
+
+ + +
+
+
With tax: 108.000000
+With tip: 124
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Lambdas

Python supports the creation of anonymous functions (i.e. functions that are not bound to a name) at runtime, using a construct called "lambda".

+

They do not have return statements.

+

Python supports functional programming. Lambdas play a role here.

+

Especially useful when you want to pass a function as a variable.

+ +
+
+
+
+
+
In [90]:
+
+
+
def foo(x):
+    return x**x
+
+f = foo(4)
+print f
+
+g = lambda l: l**l
+print g(4)
+
+ +
+
+
+ +
+
+ + +
+
+
256
+256
+
+
+
+ +
+
+ +
+
+
+
In [91]:
+
+
+
def increment (n): return lambda x: x + n
+
+sample = increment(2)
+print sample(5)
+
+print increment(2)(5)
+
+ +
+
+
+ +
+
+ + +
+
+
7
+7
+
+
+
+ +
+
+ +
+
+
+
In [46]:
+
+
+
nos = [1, 2, 3, 4, 5, 6]
+print filter(lambda x: x%2 == 0, nos)
+
+ +
+
+
+ +
+
+ + +
+
+
[2, 4, 6]
+
+
+
+ +
+
+ +
+
+
+
In [50]:
+
+
+
squares=[x**2 for x in range(1,11)]
+print filter(lambda x: (x>=30)and(x<=70),squares)
+
+ +
+
+
+ +
+
+ + +
+
+
[36, 49, 64]
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Task

+
+
+
+
+
+
+
+
+

Can you write a list-comprehension only equivalent of the above lambda?

+ +
+
+
+
+
+
+
+
+

Classes

+
+
+
+
+
+
In [92]:
+
+
+
#all class methods will have a self parameter. this is different from c++
+
+
+class Fruit(object):
+    """A class that makes various tasty fruits."""
+    def __init__(self, name, color, flavor, poisonous):
+        self.name = name
+        self.color = color
+        self.flavor = flavor
+        self.poisonous = poisonous
+
+    def description(self):
+        print "I'm a %s %s and I taste %s." % (self.color, self.name, self.flavor)
+        
+    def is_edible(self):
+        if not self.poisonous:
+            print "Yep! I'm edible."
+        else:
+            print "Don't eat me! I am super poisonous."
+
+lemon = Fruit("lemon", "yellow", "sour", False)
+
+lemon.description()
+lemon.is_edible()
+
+ +
+
+
+ +
+
+ + +
+
+
I'm a yellow lemon and I taste sour.
+Yep! I'm edible.
+
+
+
+ +
+
+ +
+
+
+
In [93]:
+
+
+
class Triangle(object):
+    number_of_sides=3
+    
+    def __init__(self,angle1,angle2,angle3):
+        self.angle1=angle1
+        self.angle2=angle2
+        self.__angle3=angle3
+        
+    def check_angles(self):
+        sum=self.angle1+self.angle2+self.__angle3
+        if sum==180:
+            return True
+        else:
+            return False
+        
+class Equilateral(Triangle):
+    angle = 60
+    
+    def __init__(self):
+        self.angle1 = self.angle
+        self.angle2 = self.angle
+        self.angle3 = self.angle
+        
+my_triangle=Triangle(45,60,60)
+my_triangle=Equilateral()
+
+print my_triangle.angle
+
+print my_triangle.number_of_sides
+print my_triangle.check_angles()
+
+my_triangle=Triangle(45,60,75)
+print my_triangle.check_angles()
+
+print my_triangle.angle2
+#Use double-underscore for private variable in the class definition
+print my_triangle.__angle3
+
+1
+
+ +
+
+
+ +
+
+ + +
+
+
60
+3
+
+
+
+ +
+
+
+---------------------------------------------------------------------------
+AttributeError                            Traceback (most recent call last)
+<ipython-input-93-e7dcceb6e42e> in <module>()
+     28 
+     29 print my_triangle.number_of_sides
+---> 30 print my_triangle.check_angles()
+     31 
+     32 my_triangle=Triangle(45,60,75)
+
+<ipython-input-93-e7dcceb6e42e> in check_angles(self)
+      8 
+      9     def check_angles(self):
+---> 10         sum=self.angle1+self.angle2+self.__angle3
+     11         if sum==180:
+     12             return True
+
+AttributeError: 'Equilateral' object has no attribute '_Triangle__angle3'
+
+
+ +
+
+ +
+
+
+
+
+
+

Miscellaneous

+
+
+
+
+
+
In [94]:
+
+
+
print 5 >> 4  # Right Shift
+print 5 << 1  # Left Shift
+print 8 & 5   # Bitwise AND
+print 9 | 4   # Bitwise OR
+print 12 ^ 42 # Bitwise XOR
+print ~88     # Bitwise NOT
+
+ +
+
+
+ +
+
+ + +
+
+
0
+10
+0
+13
+38
+-89
+
+
+
+ +
+
+ +
+
+
+
In [95]:
+
+
+
for i in range(2,6):
+    print bin(i)
+    print bin(i)[2:]
+
+ +
+
+
+ +
+
+ + +
+
+
0b10
+10
+0b11
+11
+0b100
+100
+0b101
+101
+
+
+
+ +
+
+ +
+
+
+
In [58]:
+
+
+
print int("111",2)
+print int("0b111",2)
+
+ +
+
+
+ +
+
+ + +
+
+
7
+7
+
+
+
+ +
+
+ +
+
+
+
+
+
+

Tasks..Let the games begin.

+
+
+
+
+
+
In [ ]:
+
+
+
 
+
+ +
+
+
+ +
+
+
+ +