3.2.1 Numbers

>>> x = 5 + 2 - 3 * 2    
>>> x
1
>>> 5/2
2.5 
>>> 5//2
2  
>>> 5 % 2
1
>>> 2**8
256
>>> 1000000001 ** 3
1000000003000000003000000001

>>> x = 4.3 ** 2.4
>>> x
33.137847377716483
>>> 3.5e30 * 2.77e45   
9.6950000000000002e+75
>>> 1000000001.0 ** 3 
1.000000003e+27

>>> (3 + 2j) ** (2 + 3j)
(0.68176651908903363-2.1207457766159625j)
>>> x = (3+2j) * (4+9j)
>>> x
(-6+35j)
>>> x.real 
-6.0
>>> x.imag 
35.0

>>> round(3.49)
3
>>> import math
>>> math.ceil(3.49)
4

>>> x = False
>>> x
False
>>> not x
True
>>> y = True * 2 
>>> y = 2

3.2.2 Lists

>>> x = ["first", "second", "third", "fourth"]
>>> x[0]
'first' 
>>> x[2]
'third'
>>> x[-1]
'fourth'
>>> x[-2]
'third'
>>> x[1:-1]
['second', 'third']
>>> x[0:3] 
['first', 'second', 'third']
>>> x[-2:-1]
['third']
>>> x[:3]
['first', 'second', 'third']
>>> x[-2:]
['third', 'fourth']

>>> x = [1,2,3,4,5,6,7,8,9]
>>> x[1] = "two"
>>> x[8:9] = []
>>> x
[1, 'two', 3, 4, 5, 6, 7, 8]
>>> x[5:7] = [6.0, 6.5, 7.0] 
>>> x
[1, 'two', 3, 4, 5, 6.0, 6.5, 7.0, 8]
>>> x[5:] 
[6.0, 6.5, 7.0, 8]

>>> x = [1,2,3,4,5,6,7,8,9]
>>> len(x)
9
>>> [-1,0] + x
[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> x.reverse() 
>>> x
[9, 8, 7, 6, 5, 4, 3, 2, 1]

3.2.3 Tuples

( )
(1,)
(1, 2, 3, 4, 5, 6, 7, 8, 12)
(1, "two", 3L, 4.0, ["a", "b"], (5,6))

>>> x = [1,2,3,4]
>>> tuple(x)
(1, 2, 3, 4)

>>> x = (1,2,3,4)
>>> list(x)
[1, 2, 3, 4]

3.2.4. Strings

>>> x = "live and     let \t   \tlive"
>>> x.split()
['live', 'and', 'let', 'live']
>>> x.replace("    let \t   \tlive", "enjoy life")
'live and enjoy life'
>>> import re
>>> regExpr = re.compile(r"[\t ]+")
>>> regExpr.sub(" ", x)
'live and let live'

>>> e = 2.718
>>> x = [1, "two", 3, 4.0, ["a", "b"], (5,6)]
>>> print("The constant e is:", e, "and the list x is:", x)
The constant e is: 2.718 and the list x is: [1, 'two', 3, 4.0, 
['a', 'b'], (5, 6)]
>>> print("the value of %s is: %.2f"  %  ("e", e))
the value of e is: 2.72

3.2.5 Dictionaries

>>> x = { 1:"one", 2:"two"}
>>> x["first"] = "one"
>>> x[("Delorme", "Ryan", 1995)] = (1,2,3)
>>> list(x.keys())
['first', 2, 1, ('Delorme', 'Ryan', 1995)]
>>> x[1]
'one'
>>> x.get(1, "not available")
'one'
>>> x.get(4,"not available")
'not available'

3.2.6 Sets

>>> x = set([1,2,3,1,3,5])
>>> x
{1, 2, 3, 5}
>>> 1 in x
True
>>> 4 in x
False
>>>

3.2.7 File Objects

>>> f = open("myfile", "w")
>>> f.write("First line with necessary newline character\n")
44
>>> f.write("Second line to write to the file\n")
33
>>> f.close()
>>> f = open("myfile", "r")
>>> line1 = f.readline()
>>> line2 = f.readline()
>>> f.close()
>>> print(line1, line2)
First line with necessary newline character
 Second line to write to the file
>>> import os
>>> print(os.getcwd())
c:\My Documents\test
>>> os.chdir(os.path.join("c:","My Documents", "images"))
>>> filename = os.path.join("c:", "My Documents",
>>> "test", "myfile")
>>> print(filename)
c:\My Documents\test\myfile
>>> f = open(filename, "r")
>>> print(f.readline())
First line with necessary newline character
>>> f.close()

3.3.2 If-elif-else

x = 5
if x < 5:
    y = -1
    z = 5
elif x > 5:
    y = 1
    z = 11
else:
    y = 0
    z = 10

print(x, y, z)

5 0 10

3.3.3 While loop

u, v, x, y = 0, 0, 100, 30
while x > y:
    u = u + y
    x = x - y
    if x < y +2:
        v = v + x
        x = 0
    else:
        v = v + y +2
        x =x -y -2

print(u, v)

60 40


3.3.4 for loop

item_list = [3, "string1", 23, 14.0, "string2", 49, 64, 70]
for x in item_list:
    if not isinstance (x, int):
        continue
    if not x % 7:
        print("found an integer divisible by seven: %d" % (x))
        break

found an integer divisible by seven: 49


3.3.5 Functions

>>> def funct1(x, y, z):
...     value = x + 2*y + z**2
...     if value > 0:
...         return x + 2*y + z**2
...     else:
...         return 0 
...
>>> u, v = 3,4
>>> funct1(u, v, 2)
15
>>> funct1(u, z=v, y=2)
23
>>> def funct2(x, y=1, z=1):
...     return x + 2*y + z**2
...
>>> funct2(3, z=4)
21
>>> def funct3(x, y=1, z=1, *tup):
...     print((x,y,z)+ tup)
...
>>> funct3(2)
(2, 1, 1)
>>> funct3(1,2,3,4,5,6,7,8,9)
(1, 2, 3, 4, 5, 6, 7, 8, 9)
>>> def funct4(x, y=1, z=1, **dict):
...     print(x, y, z, dict)
>>> funct4(1, 2, m=5, n=9, z=3)
1 2 3 {'n': 9, 'm': 5}

#.5 Object-oriented programming

>>> import sh
>>> c1 = sh.Circle()
>>> c2 = sh.Circle(5, 15, 20)
>>> print(c1)
Circle of radius 1 at coordinates (0, 0)
>>> print(c2)
Circle of radius 5 at coordinates (15, 20)
>>> c2.area()
78.539749999999998
>>> c2.move(5,6)
>>> print(c2)
Circle of radius 5 at coordinates (20, 26)