Python for beginners: Difference between revisions

Latest revision as of 15:04, 21 November 2020

Next pages: Collections // Loops and Conditions // Create anthology

=== VARIABLES ===

Introduction to the objects string & list with their different attributes
uses the shell

# USING STRINGS

A string is a chain of characters / text and can contain any type of characters

A string is defined by " "

* Write text using STRING

>>> print("La Cambre")

- Exercise: Write your name

>>> ...

* Adding text

>>> print("Brussels"+"Paris")

>>> print("Brussels "+"Paris")

- Exercise: Write your address

* Composing a sentence

>>> print("Paris", "to", "London", "via", "Brussels")

>>> print("Paris to London via Brussels")

- Exercise: Write your favourite expression

* Multiply

>>> print(3*3)

>>> 3 * "algolit" + " in Brussels"

- Exercise: Write 'I write the alphabet' 3 times.

Note: there are always different possible solutions

* Write a string as a variable

- Avoids having to retype your string each time you use it
- You can change values at any time of the writing process

>>> letter = "a"

>>> print(letter)

>>> word = "algolit"

>>> print(word)

>>> sentence = "I learn to read and write again in Python."

>>> print(sentence, letter)

- Exercise: Print your letter, word, sentence

* Add punctuation

>>> print(letter + " " + word + " " + sentence + ".")

>>> print(letter + "! " + word + "? " + sentence + ".")

>>> letter = "i"

>>> print letter + "! " + word + "? " + sentence + "."

- Exercise: change content of one of variables, over and over, see how result changes

* Calculate!

- the length of the string

>>> print(len(letter)) >>> print(len(word)) >>> print(len(sentence)) >>> print(len(word))+2)

- and more

a_number = len(word)+2 print(a_number) a_number += 3 print(a_number)

- Exercise: Compose a sentence word by word, specifying each word as a variable. The length of the sentence is 20.

What you've learned

variable
value
assignment operator (=)
difference between variables and values
integers
print()

@@ Line 1: / Line 1: @@
-== Literary Python for Beginners ==
+Next pages: [[Python_for_beginners/collections|Collections]] // [[Python_for_beginners/loops_and_conditions|Loops and Conditions]] // [[Python_for_beginners/anthology|Create anthology]]
-=== LETTER * WORD * SENTENCE ===
+'''=== VARIABLES ==='''
 * Introduction to the objects string & list with their different attributes
-* uses the shell or integrated development environment
+* uses the shell
-** run python 2.7 – installed by default on all platforms (Ubuntu, Mac, Windows)
+'''# USING STRINGS'''
-$ python
+A string is a chain of characters / text and can contain any type of characters
->>>
+A string is defined by " "
-** install python idle 2.7 – ways to interact with Python: shell + editor
+'''* Write text using STRING'''
+>>> print("La Cambre")
-'''# USING STRINGS'''
+** Exercise: Write your name'''
-A string is a chain of characters / text and can contain any type of characters
-A string is defined by " "
+>>> ...
-'''* write letter using STRING'''
->>> "a"
+'''* Adding text'''
-'''* write several letters'''
+>>> print("Brussels"+"Paris")
->>> "a, b, c, d"
+>>> print("Brussels "+"Paris")
-'''* write combinations'''
+** Exercise: Write your address'''
->>> "a" + "b"
->>> 3
+'''* Composing a sentence'''
->>> "a" + "and" + "b"
+>>> print("Paris", "to", "London", "via", "Brussels")
->>> "a" + " and " + "b"
+>>> print("Paris to London via Brussels")
->>> "a" + "+ " + 3 + " is a3"  ***
+** Exercise: Write your favourite expression'''
->>> 3*3
->>> "a" + "+ " + "3" + " is a3"
+'''* Multiply'''
->>> 3 * "algolit" + " in wtc25"
+>>> print(3*3)
+>>> 3 * "algolit" + " in Brussels"
-** Exercise: Write 'I write the alphabet 3 times.'
+** Exercise: Write 'I write the alphabet' 3 times.
 Note: there are always different possible solutions
-'''* write string as variable'''
+'''* Write a string as a variable'''
 ** Avoids having to retype your string each time you use it
@@ Line 62: / Line 59: @@
 >>> letter = "a"
->>> print letter
+>>> print(letter)
 >>> word = "algolit"
->>> print word
+>>> print(word)
->>> sentence = "I learn to read and write again at wtc25"
+>>> sentence = "I learn to read and write again in Python."
->>> print sentence, letter
+>>> print(sentence, letter)
-** Exercise: print your letter, word, sentence
+** Exercise: Print your letter, word, sentence
-'''* add punctuation'''
+'''* Add punctuation'''
->>> print letter + " " + word + " " + sentence + "."
+>>> print(letter + " " + word + " " + sentence + ".")
->>> print letter + "! " + word + "? " + sentence + "."
+>>> print(letter + "! " + word + "? " + sentence + ".")
 >>> letter = "i"
@@ Line 88: / Line 85: @@
-'''* calculate!'''
+'''* Calculate!'''
 ** the length of the string
->>> len(letter)
+>>> print(len(letter))
->>> len(word)
+>>> print(len(word))
->>> len(sentence)
+>>> print(len(sentence))
+>>> print(len(word))+2)
-** we can also consider the letter/word/sentence as fields or grids, in which each letter occupies a specific position
-Note:  computer starts to count from 0
->>> word[0]
->>> word[3]
-** Exercise: what is the middle letter of your sentence?
-'''* Slicing and concatenating strings in order to select letters & compose new words'''
-** find last letter
->>> zin[-1]
-** find last but one letter
->>> word[-2]
-** find first two letters
->>> word[0:2]
-or
->>> word[:2]
-** find 3 letters in the middle
->>> word[2:5]
-** find from 3rd letter till end
->>> word[2:]
-** Exercise: If the word is "solidarity" is, what do you read here?
-word[:5] + word[3:]
-** Exercise: rewrite the word as 'liquidity', using slicing
-'''* write with capitals'''
->>> print letter.lower()
->>> print sentence.upper()
-'''* write first word of sentence with capital letter'''
->>> print sentence.capitalize()
-'''* note the difference'''
->>> sentence.title()
->>> word.title()
-'''From STRINGS to LISTS'''
-'''
-* LISTS are MUTABLE vs immutable STRINGS'''
-That is the reason you want to change your string into a list:
->>> sentence.split()
-and save it as a new variable:
->>> list_words = sentence.split()
-'''* some of the attributes of string can be used for lists'''
-** Exercise: which previously mentioned attributes function for lists?
-'''* replace a word in a list'''
->>> list_words[3] = "wtc25"
->>> print list_words
-'''* remove words'''
->>> list_words[2:3] = []
-Note: list_words[2] = [] → this removes your 3rd element and replaces it by an empty sublist ('nested list')
-'''* put back words'''
->>> list_words[2:3] = ["so", "exciting"]
-'''* shorten a list'''
->>> list_words[-3:]
-* and save the shortened list into a new variable – the old continues to exist
->>> yezzzz = list_words[-3:]
-'''* combine lists, group two in one'''
->>> text = [list_words, yezzzz]
-* call an element of a sublist
->>> word = text[1][2]
-'''* concatenate lists, merge two into one'''
->>> print(list_words + yezzzz)
->>> poem = list_words + yezzzz
-'''*add words to your list'''
->>> poem.append("is")
->>> print(poem)
-'''* sort your list alphabetically'''
->>>  poem.sort()
-'''* transform your list into a string again'''
->>> " ".join(poem)
+** and more
-NOTE: the whitespace / try without
+a_number = len(word)+2
+print(a_number)
+a_number += 3
+print(a_number)
->>> " ".join(poem) + "?"
+** Exercise: Compose a sentence word by word, specifying each word as a variable. The length of the sentence is 20.
-* empty your list // you have a brand new sheet of paper :-)
->>> poem[:] = []
+'''What you've learned'''
+* variable
+* value
+* assignment operator (=)
+* difference between variables and values
+* integers
+* print()

Python for beginners: Difference between revisions

From Algolit

Latest revision as of 15:04, 21 November 2020