First Line Of Code

print('Hello My Lovely!')

Data Type

• int
• float
• str
• boolean

print(1+2) -- 3
print(1+2.5) -- 3.5
print(1+'2') -- Type Eror can't add str with int

Variabel

Name that we give to certain values on our code

a = 2+3
-- a here is variabel

Function

Function is usefull for reusable code

def luasSegitga(alas, tinggi):
	return luas = alas*tinggi/2

Comparison Operators

Python comparison operators return Boolean results: True or False.

Comparison Operators With Strings

Python use to compare very left unicode number from this table when doing with string:

Logical Operators

When Python logical operators are used with comparison operators, the interpreter will return Boolean results (True or False):

Membership Operators

If - Elif - Else Statement

For Loops and Nested Loops

While Loops

Recursion

this usefull when we work on like Tree sturcture. can count all the goup on sub branch or subsub branch in one file. (A recursive function will usually have this structure)

A recursive function must include a recursive case and base case. The recursive case calls the function again, with a different value. The base case returns a value without calling the same function.

A recursive function will usually have this structure:

def recursive_function(parameters):
    if base_case_condition(parameters):
        return base_case_value
    recursive_function(modified_parameters)

Make List then Print into one single string

    n = int(input()) # make input feature
    num = list(range(1,n+1)) # make list dengan isi 1,2,3
 
    # for loop to convert int to str
    for i in range (n):
        num[i]=str(num[i])
 
    print(''.join(num))

String operations

• len(string) - Returns the length of the string
• for character in string ****Iterates over each character in the string
• if substring in string Checks whether the substring is part of the string
• string[i] - Accesses the character at index i of the string, starting at zero
• string[i:j] Accesses the substring starting at index i, ending at index j minus 1. If i is omitted, its value defaults to 0. If j is omitted, the value will default to len(string).

String methods

• string.lower() Returns a copy of the string with all lowercase characters
• string.upper() Returns a copy of the string with all uppercase characters
• string.lstrip() ****Returns a copy of the string with the left-side whitespace removed
• string.rstrip() ****Returns a copy of the string with the right-side whitespace removed
• string.strip() Returns a copy of the string with both the left and right-side whitespace removed
• string.count(substring) - Returns the number of times substring is present in the string
• string.isnumeric() - Returns True if there are only numeric characters in the string. If not, returns False.
• string.isalpha() Returns True if there are only alphabetic characters in the string. If not, returns False.
• string.replace(old, new) Returns a new string where all occurrences of old have been replaced by new.
• delimiter.join(list of strings) Returns a new string with all the strings joined by the delimiter

  ' '.join(['this', 'is', 'try'])

will print ‘this is try’

• string.split()

  'this is try'.split()
   

  will print ['this', 'is', 'try']

• string.split(delimiter) - Returns a list of substrings that were separated by whitespace or a delimiter

• format method

print("hello {}, your lucky number is {}".format(name, number))

• format expression

price = 7.5
price_with_tax = price*1.09
 
print("base price: ${:2f}. With tax: ${:2f}".format(price, price_with_tax))

will print “base price: $7.50. With tax: $8.18”

Another Example:

“>” for Alight to right, “>6” for Alight to right on 6 spaces

List

x = []

def get_word(sentence, n):
	# Only proceed if n is positive
	if n > 0:
		words = sentence.split()
		# Only proceed if n is not more than the number of words
		if n <= len(words):
			return(words[n-1])
	return("")
 
print(get_word("This is a lesson about lists", 4)) # Should print: lesson
print(get_word("This is a lesson about lists", -4)) # Nothing
print(get_word("Now we are cooking!", 1)) # Should print: Now
print(get_word("Now we are cooking!", 5)) # Nothing

Adding Data into List

df = [1,2,3,4]

• Using append()

df.append(5)
##will make df = [1,2,3,4,5]

• Using Insert()

df.insert(0,'nomo')
#will make df = ['nomo',0,1,2,3,4,5]

Remove data from List

df = ['nomo',0,1,2,3,4,5]

• using remove()

df.remove('nomo')
#will make df = [0,1,2,3,4,5]

• using pop()

df = ['nomo',0,1,2,3,4,5]
df.pop(2)
#will make df = ['nomo',0,2,3,4,5]

Changing data from list

df = ['nomo',0,1,2,3,4,5]
df[0] = 9
#will make df = [9,0,1,2,3,4,5]

List Comprehension

number = []
for x in range (1,10):
	number.append(x)
number
## Output : 1,2,3,4,5,6,7,8,9

Actually that task can write on shorter code like

number = [x for x in range (1,10)]

other example

def odd_numbers(n):
	return [x for x in range (1,n+1) if x % 2 != 0]
 
print(odd_numbers(5))  # Should print [1, 3, 5]

Tuple

like list but immutable

def file_size(file_info):
	fileName, fileType, bytes= file_info
	return("{:.2f}".format(bytes / 1024))
 
print(file_size(('Class Assignment', 'docx', 17875))) # Should print 17.46
print(file_size(('Notes', 'txt', 496))) # Should print 0.48
print(file_size(('Program', 'py', 1239))) # Should print 1.21

Iterating over Lists and Tuples

animals = ["Lion", "Zebra", "Dolphin", "Monkey"]
chars = 0
for animal in animal:
	chars += len(animal)
print("Total characters: {}, Average length {}".format(chars, chars/len(animals)))
 
#Output : Total characters: 22, Average length 5.5

Enumerate Function

winners = ["Ashley", "Dylan", "Reese"]
for index, person in enumerate(winners):
	print("{} - {}".format(index + 1, person))
 
#Output : 1 - Ashley
			#   2 - Dylan
			#   3 - Reese

Use Case

• Problem Say you have a list of tuples containing two strings each. The first string is an email address and the second is the full name of the person with that email address. You want to write a function that creates a new list containing one string per person including their name and the email address between angled brackets. the format usually used in emails like this.

• Solution

  # build fucntin to print Name, then email
  def full_name(people):
  	result = []
  	for email, name in people:
  		result.append("{} <{}>".format(name, email))
  	return result
   
  #test the function
  	print(full_name([("fathin@gmail.com", "Fathin Afif"), ("abc@example.com", "abc")]))
  	#Output : ['Fathin Afif <fathin@gmail.com>', 'abc <abc@gmail.com>']

• other code

  def skip_elements(elements):
  	df = []
  	for index, elemen in enumerate(elements):
  		if index%2 == 0:
  			df.append(elemen)
  	return df
   
  print(skip_elements(["a", "b", "c", "d", "e", "f", "g"])) # Should be ['a', 'c', 'e', 'g']
  print(skip_elements(['Orange', 'Pineapple', 'Strawberry', 'Kiwi', 'Peach'])) # Should be ['Orange', 'Strawberry', 'Peach']

  Dictionary

  mhs1: {
      "nama" : "fathin afif",
      "email" : "fathinafiff@gmail.com"
  }
  prodi = {
      "teknik" : ["mesin", "industri"],
      "mipa" : ["matematik", "fisika"]
  }

  Access the data

  # Access data from mhs1
  mhs1["nama"]
   
  #Access data from prodi
  prodi["teknik"]
  --
  prodi["teknik"][0]
  ## output : "mesin"

  Add and delete new key

  # add new key into mhs1
  mhs1["hp"] : "082365294643"
   
  #delete key
  del mhs1["email"]

  Usefull function on Dictionary

  file_counts = {
      "jpg":10,
      "txt":14,
      "csv":2,
      "py":23
  }

  dic.items()

  this will print the keys with the values

  dic.keys()

  this will print the key of dictionary dic.values() this will print the values of dictionary

  Operations

  • len(dictionary) - Returns the number of items in a dictionary.
  • for key, in dictionary Iterates over each key in a dictionary.
  • for key, value in dictionary.items() Iterates over each key,value pair in a dictionary.
  • if key in dictionary - Checks whether a key is in a dictionary.
  • dictionary[key] - Accesses a value using the associated key from a dictionary.
  • dictionary[key] = value Sets a value associated with a key.
  • del dictionary[key] Removes a value using the associated key from a dictionary.

  Methods

  • dictionary.get(key, default) Returns the value corresponding to a key, or the default value if the specified key is not present.
  • dictionary.keys() Returns a sequence containing the keys in a dictionary.
  • dictionary.values() Returns a sequence containing the values in a dictionary.
  • dictionary[key].append(value) - Appends a new value for an existing key.
  • dictionary.update(other_dictionary) - Updates a dictionary with the items from another dictionary. Existing entries are updated; new entries are added.
  • dictionary.clear() Deletes all items from a dictionary.
  • dictionary.copy() Makes a copy of a dictionary.

  Case Study #1

  cool_beasts = {"octopuses":"tentacles", "dolphins":"fins", "rhinos":"horns"}
  for animal, tool in cool_beasts.items():
      print("{} have {}".format(animal, tool))

  output :

  Case Study #2

  def count_letter(text):
      result = {}
      for letter in text:
          if letter not in result:
              result[letter] = 0
          result[letter] += 1
      return result

  output: