Module 1 - Day 3

def twice(x):
    return 2*x

def say_hello(name):
    print("Hello", name,"!")

twice(4) # it looks like print but it is not .. it is response of interpreter to call of function

say_hello("arcesium")

Hello arcesium !

def func():
    pass # pass is a statement that does nothing

def func1():

SyntaxError: incomplete input (2040221739.py, line 5)

func() # there will not print, no interpreter response

x_2 = twice(5)

x_2

result = func()

result # there is nothing in it

print(result)

None

Any function that does not have return statement in it, will by defualt resturn None

def say_hello(name):
    print("Hello", name,"!")

r_hello = say_hello("arcesium")

Hello arcesium !

print(r_hello) # because there is not return statement in say_hello

None

Two types of functions

one that does some computation and returns the value
one that does something (print to screen, write to file, starting service on the system) ..may not return value

%load_problem simple_interest

Problem: Simple Interest

Write a function simple_interest to compute simple interest. It takes three arguments, principal amount, rate of interest and time (in years) and returns simple interest accumulated on given principal amount for given number of years for given rate of interest.

>>> simple_interest(10000,8,5)
4000.0
>>> simple_interest(100,3,1)
3.0

You can verify your solution using:

%verify_problem simple_interest

# your code here

def simple_interest(P, N, R):
    return P*N*R/100

%verify_problem simple_interest

✓ simple_interest(100, 4, 5)
✓ simple_interest(100, 5, 5.0)
🎉 Congratulations! You have successfully solved problem simple_interest!!

%load_problem mean

Problem: Mean

Write a function mean to compute the arthematic mean of a list of numbers.

The arthemetic mean of N numbers is computed by adding all the N numbers and dividing the total by N.

The function takes the list of numbers as argument and returns the mean.

>>> mean([1, 2, 3, 4, 5])
3.0

You can verify your solution using:

%verify_problem mean

# your code here

nums = list(range(21))

len(nums)

sum(nums)

max(nums)

min(nums)

sum = 1 + 2 + 3  + 4

sum

nums

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

sum(nums)

TypeError: 'int' object is not callable

sum

sum

del sum # this deletes the variable from namespace

sum_ = 1 + 2 + 3  + 4

sum_

sum(nums)

nums

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

sum(nums)

def mean(numbers):
    sum_ = sum(numbers)
    return sum_/len(numbers)

%verify_problem mean

✓ mean([1, 2, 3, 4, 5])
✓ mean([5])
🎉 Congratulations! You have successfully solved problem mean!!

x = [10, 20, 30, 40, 50]

sum(x)

x[0] + x[1] + x[2] + x[3] + x[4]

def mean_first_n(n):
    nums = range(n)
    return sum(nums)/len(nums)

ones = [1, 1, 1, 1, 1]

len(ones) # becasue there are five ones in it..length will be 5

str(ones)

'[1, 1, 1, 1, 1]'

text = str(ones)

text[0]

'['

text[1]

'1'

text[2]

','

text[3]

' '

mean([1, 1, 2, 3, 4])

2.2

mean(1, 2) # this means I am passing two arguments 1 and 2

TypeError: mean() takes 1 positional argument but 2 were given

mean([1, 2]) # this means I am passing one argument as a list

1.5

def twice(x):
    return 2*x


def twice1(x):
    print(2*x)

twice(5)

twice1(5)

x = twice(5)

y = twice1(5)

print(y)

None

twice(twice(5))

twice1(twice1(5)) # the inner most call will be successful,

TypeError: unsupported operand type(s) for *: 'int' and 'NoneType'

None*2

TypeError: unsupported operand type(s) for *: 'NoneType' and 'int'

String Methods

len, sum, int, str, list, range ..these are some built in functions that we saw. Many more functionalies are provided by methods which come as part of string object

sentence = "There Are Few Wise Words"

sentence.startswith("The") # this expects one argument

True

sentence.endswith("x")

False

sentence.endswith("s")

True

sentence.endswith("Words")

True

sentence.isupper() # just asking a question

False

True # boolean data types

True

False

False

sentence.upper() # this will return a new text with everything converted upper case

'THERE ARE FEW WISE WORDS'

sentence

'There Are Few Wise Words'

sentence.isalpha() # does this have all chars from english alphabets

False

"asasas".isalpha()

True

"test123".isalnum() # does this have alphabets or numbers?

True

text = "hello world"

text.capitalize()

'Hello world'

text.title()

'Hello World'

sentence

'There Are Few Wise Words'

sentence.replace("Wise", "Foolish")

'There Are Few Foolish Words'

help(sentence.replace)

Help on built-in function replace:

replace(old, new, count=-1, /) method of builtins.str instance
    Return a copy with all occurrences of substring old replaced by new.
    
      count
        Maximum number of occurrences to replace.
        -1 (the default value) means replace all occurrences.
    
    If the optional argument count is given, only the first count occurrences are
    replaced.

sentence.split() # this will split given text into words... word boundaries are whitespaces

['There', 'Are', 'Few', 'Wise', 'Words']

words = sentence.split()

words

['There', 'Are', 'Few', 'Wise', 'Words']

words[0]

'There'

words[-1]

'Words'

len(sentence.split()) # how many words are there

dashed = "This-is-another-text-with-dash-in-it-instead-of-space"

dashed.split() # beacasue by default word boundary is taken as while spaces

['This-is-another-text-with-dash-in-it-instead-of-space']

dashed.split("-")

['This',
 'is',
 'another',
 'text',
 'with',
 'dash',
 'in',
 'it',
 'instead',
 'of',
 'space']

"this,is,comma,separated".split(",")

['this', 'is', 'comma', 'separated']

multilinetext = """this is first line
this is second line
this is third line"""

print(multilinetext)

this is first line
this is second line
this is third line

multilinetext # interprester response ... here you will be able to see the exact character stored in this text

'this is first line\nthis is second line\nthis is third line'

print(multilinetext)

this is first line
this is second line
this is third line

filetext = '''some lines
from a file
are here
and we have read them
using python'''

filetext

'some lines\nfrom a file\nare here\nand we have read them\nusing python'

filetext.split("\n") # this will split the text using newline char ... so I will get list of lines

['some lines',
 'from a file',
 'are here',
 'and we have read them',
 'using python']

lines = filetext.split("\n")

lines

['some lines',
 'from a file',
 'are here',
 'and we have read them',
 'using python']

nums

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

a = [1, 2, 3, 4, 5]

a = [1,
     2,
     3,
     4,
     5]

[1, 2, 3, 4, 5]

dashed.replace("-", " ") # this will return new string with the changes. original remains as it is

'This is another text with dash in it instead of space'

dashed

'This-is-another-text-with-dash-in-it-instead-of-space'

Any string method will not change the original string, it will always return a new string

string is immutable object, once created it can not be modified.

sometext = "   -hello-one-two-three"

sometext.split("-")

['   ', 'hello', 'one', 'two', 'three']

sometext.strip() # string will remove trailing spaces

'-hello-one-two-three'

sometext.strip().split("-")

['', 'hello', 'one', 'two', 'three']

dashed

'This-is-another-text-with-dash-in-it-instead-of-space'

dashed.replace("-"," ").replace("text", "string") # this is mehtod chaining

'This is another string with dash in it instead of space'

len(str(12131)) # this is nested call of functions

dashed.split("-")

['This',
 'is',
 'another',
 'text',
 'with',
 'dash',
 'in',
 'it',
 'instead',
 'of',
 'space']

words

['There', 'Are', 'Few', 'Wise', 'Words']

" ".join(words) # join method on string expects a list of strings

'There Are Few Wise Words'

"-".join(words)

'There-Are-Few-Wise-Words'

",".join(words)

'There,Are,Few,Wise,Words'

morewords = dashed.split("-")

morewords

['This',
 'is',
 'another',
 'text',
 'with',
 'dash',
 'in',
 'it',
 'instead',
 'of',
 'space']

",".join(morewords[:3])

'This,is,another'

",".join(morewords[:3])  + "-".join(morewords[3:])

'This,is,anothertext-with-dash-in-it-instead-of-space'

def join_with_comma_dash(words, n):
    return ",".join(words[:n]) + "-".join(words[n:])

join_with_comma_dash(morewords, 5)

'This,is,another,text,withdash-in-it-instead-of-space'

join_with_comma_dash(morewords, 8)

'This,is,another,text,with,dash,in,itinstead-of-space'

def join_with_comma_dash(words, n):
    return ",".join(words[:n]) + "|" + "-".join(words[n:])

join_with_comma_dash(morewords, 6)

'This,is,another,text,with,dash|in-it-instead-of-space'

"hello" + "world"

'helloworld'

def join_with_comma_dash(words, n):
    return "|".join([",".join(words[:n]) ,
                     "-".join(words[n:])])

join_with_comma_dash(morewords, 6)

'This,is,another,text,with,dash|in-it-instead-of-space'

def join_with_comma_dash(words, n):
    return ",".join(words[:n]) + "|" + "-".join(words[n:])

words

['There', 'Are', 'Few', 'Wise', 'Words']

morewords

['This',
 'is',
 'another',
 'text',
 'with',
 'dash',
 'in',
 'it',
 'instead',
 'of',
 'space']

morewords[:5]

['This', 'is', 'another', 'text', 'with']

morewords[5:]

['dash', 'in', 'it', 'instead', 'of', 'space']

morewords[4:]

['with', 'dash', 'in', 'it', 'instead', 'of', 'space']

List methods

List has methods to find items. these methods return!

nums = [1, 2, 3, 4]

nums.index(3)

X = [1, 2, 3, 3, 3, 5, 6]

X.index(3) # it will give occurence

words

['There', 'Are', 'Few', 'Wise', 'Words']

words.index("There")

words.index("Few")

words.index("what")

ValueError: 'what' is not in list

ones = [1, 1, 1, 1, 1, 1, 1]

ones.count(1)

Mehtod to add new items in the list. These methods do not return but change the original list

empty = []

empty.append(1) # it will not return any value, but it will change original list

empty

[1]

empty.append(2)

empty

[1, 2]

empty.append(5)

empty

[1, 2, 5]

empty.insert(0, 23) # at location 0 insert 23

empty

[23, 1, 2, 5]

empty.remove(23)

empty.insert(0, 24)

empty

[24, 1, 2, 5]

empty.clear() # will delete all items from the list

empty

[]

ones = [1, 1, 1]
twos = [2, 2, 2]

ones.extend(twos) # add all items from second list into first one ..at end

ones

[1, 1, 1, 2, 2, 2]

twos

[2, 2, 2]

nums = [232, 4332, 12, 3, 2, 43]

sorted(nums) # will sort the list and will return a list

[2, 3, 12, 43, 232, 4332]

nums.sort() # method ... will sort the list inplace. we will loose the original list

nums

[2, 3, 12, 43, 232, 4332]

sorted(nums, reverse=True)

[4332, 232, 43, 12, 3, 2]

nums.sort(reverse=True)

nums

[4332, 232, 43, 12, 3, 2]

ones.extend(2)

TypeError: 'int' object is not iterable

ones.extend("text") # this will take very char from "text" and put as a seperate item in ones

ones

[1, 1, 1, 2, 2, 2, 't', 'e', 'x', 't']

sorted("Let me sort these chars")

[' ',
 ' ',
 ' ',
 ' ',
 'L',
 'a',
 'c',
 'e',
 'e',
 'e',
 'e',
 'h',
 'h',
 'm',
 'o',
 'r',
 'r',
 's',
 's',
 's',
 't',
 't',
 't']

def sorttext(text):
    return "".join(sorted(text))

sorttext("LET us sort htis out")

'    ELThioorssstttuu'

%load_problem numeric_value

Problem: Numeric Value

In financial terms a negative balance is represented with round barackets around the number instead of - sign. Write a function numeric_value which returns actual numeric value. For example a value "(1234)" should get -1234 as numeric value. while "34" will get value as 34

>>> numeric_value("(1234)")
-1234
>>> numeric_value("42")
42

You can verify your solution using:

%verify_problem numeric_value

# your code here

%load_problem reverse_digits

Problem: Reverse Digits

Write a function reverse_digits which will reverse digits of multi digit number and return new formed integer.

>>> reverse_digits(1234)
4321

You can verify your solution using:

%verify_problem reverse_digits

# your code here