I will summarize Python to deepen my understanding. I will update it from time to time.
References ☆ Daigo Kunimoto / Akiyoshi Sudo "Introduction to Python for a refreshing understanding"
The extension of the source file is " .py "
-By Python interpreter (: software)
Convert source code to machine language (: computer-understandable language)
-If there is a grammatical error, SyntaxError is displayed.
-Execution is canceled at the time of Exception (: error at runtime)
//: The quotient of division (the answer is an integer)
**: Exponentiation
*: String iteration (string * number or number * string)
[Priority]
High: **
Medium: *, /, %
Low: +, -
print(1 + 1 * 7) --8
print ((1 + 1) * 7) --14, parentheses can be used to increase priority
print ('Good morning \ n you guys \') print ('\ "and '')
Special symbols used when using string literals
\ n: Line break
\\: Backslash
\': Single quote
\" : Double quotes
Variable name = value # variable assignment Variable name #variable reference
print ('The diameter of a circle with a radius of 7 is') ans = 7 * 2 --assignment print (ans) --See print ('circumference') print(ans * 3.14)
name, age ='John', 33 --Unpacked assignment (: How to define multiple variables together)
import keyword
print(keyword.kwlist)
-A word that cannot be used as a identifier (: a sequence of letters and numbers used in a name)
・ You can check with the above code
・ When you want to fix the contents, you often name it with capital letters.
age + = 1-Same as "age = age + 1" price * = 1.1-Same as "price = price * 1.1"
Variable name = input (string)
name = input ('Tell me your name!') print ('Welcome!' + Name)
Assign keyboard input to variables
Data type is str type
[Main list]
int: integer
float: decimal
str: string
bool: Boolean value
[conversion]
int function: Truncate decimals, string will result in error
float function: String will result in error
str function
bool function
・ Only character strings or numerical values can be concatenated.
-Python does not have implicit type conversion (: mechanism for automatic type conversion), so Must do explicit type conversion`
type (variable name) int (variable name) float (variable name) str (variable name) bool (variable name)
x = 3.14
y = int (x) --int function print(y) print (type (y)) --type function z = str (x) --str function print(z) print(type(z)) print(z * 2)
Variables do not have a data type (= any data type value can be assigned)
➡︎ Find out which data type is stored
'String containing {}'. format (value 1, value 2 ...)
name ='God' age = 77 where print ('my name is {}, year is {}') .format (name, age)-{} embeds the value
You can embed a value in a string
{} ＝ Placeholder
print (f'My name is {name}, year is {age}')
Features introduced in Python 3.6
It is possible to directly specify the variable name (expression is also OK) in the placeholder
A mechanism for grouping related data and treating it as a single variable
Variable name = [Element 1, Element 2 ...] #Definition List [subscript] # reference List [changed value subscript] = changed value #change
members = ['Sato',' Tanaka','Suzuki'] members [0] ='Kobayashi'-"Sato" is changed to "Kobayashi" print(members) print(members[0])
[Purpose of use]
Combine multiple data with order intoone
sum (list)
scores = [70, 80, 90]
total = sum(scores)
print ('The total is {} points.'. Format (total))
-Calculate the total value of list elements
-Cannot be used in the list that contains the string
・ Can also be used for tuples and sets
len (list)
scores = [70, 80, 90]
avg = total / len(scores)
print ('The average is {} points.'. Format (avg))
-Calculate the mean of list elements
・ Can also be used for dictionary, tuple, and set
List .append (append value)
members.append('Charotte')
Add to the end of the list element
List .remove
members.remove('Charotte')
Delete the specified value from the list element
List variable [A: B] #Refer to the element of subscript A or more and less than B List variable [-A] # Reference (Negative number specified)
scores = [70, 80, 90, 100]
print(scores[0:2]) --70,80
print(scores[1:]) --80,90,100
print(scores[:3]) --70,80,90
print(scores[:]) --70,80,90,100
print(scores[-3]) --80
You can specify the range of list elements
A: ➡︎ Elements above subscript A
: B➡︎ Elements less than subscript B
: ➡︎ All elements
-A➡︎ Count from the end of the list ("1"at the beginning of counting)
Variable name = {Key 1: Value 1, Key 2: Value 2 ...} #Definition Dictionary name [key name] # reference Dictionary name [additional key name] = additional value #addition Dictionary name [change key name] = changed value #change
scores = {'Japanese Language':70, 'Mathmatics':80, 'Science':90, 'Social Studies':100}
scores['English'] = 88
scores['Science'] = 98
print(scores['Social Studies'])
[Purpose of use]
Manage multiple data with key
➡︎ Ordering added from Python 3.7
-- No data type specified Duplicate keys are possible (not recommended) Keys are case sensitive
del Dictionary name [key name to delete]
del scores['Mathmatics']
Delete the dictionary element
Dictionary name.values ()
total = sum(scores.values())
print(total)
Calculate the total value of dictionary elements
Variable name = (value 1, value 2 ...)
points = (1, 2, 3)
print(points)
members = ('James',) --Tuple with only one element (with a comma after the value) print(type(members))
Has characteristics similar to lists (however, elements cannot be added, changed, or deleted)
Collectively referred to as sequence with the list
[Purpose of use]
Unable to rewrite Combine multiple data into one
Variable name = {value 1, value 2 ...}
numbers = {10, 20, 30, 30}
print(numbers)
It also has similar characteristics to lists (but not duplicate, no subscripts & keys, no order)
[Purpose of use]
Manage type as data
Set .add (additional value)
scores.add(100);
Used in place of append function in set
Also, the set has a tailless element, so it's just added.
list function: Convert to list * In the case oflist (), an empty collection is created
tuple function: Convert to tuple
set function: Convert to a set
scores = {'Japanese Language':70, 'Mathmatics':80, 'Science':90, 'Social Studies':100}
members = ['John', 'Mike', 'Jack']
print (tuple (members)) --Convert members to tuples print (list (scores)) --Convert scores to list print (set (scores.values ())) --Convert scores to a set
dict (zip (list of keys, list of values)) #Convert to dictionary
a_scores = {'Japanese Language':70, 'Mathmatics':80, 'Science':90, 'Social Studies':100}
b_scores = {'Japanese Language':100, 'Mathmatics':90, 'Science':80, 'Social Studies':70}
member_scores = {
'A' = a_scores,
'B' = b_scores,
}
--
member_likes = {
'C': {'Cat','Strawberry'}, 'D': {'Dog','Mikan'} } print (member_likes) --Show everyone's likes print (member_likes ['C']) --Display C likes -- x = [1, 2, 3] y = [11, 22, 33] z = [a, b] --A two-dimensional list with a as 0th and b as 1st (: structure that incorporates another list in the list) print (z) --z See whole print (z [0]) --see list x in z print (z [1] [2]) --See list y in z
Set 1 & Set 2
member_likes = {
'E': {'Baseball',' Meat'},
'F': {'Fish',' Baseball'}
}
common_likes = member_likes['E'] & member_likes['F']
print(common_likes)
Features of set only
Find the commons and differences of two sets
[Set operator]
| Operator: Union
-Operator: Difference set
& operator: intersection
^ Operator: Symmetric difference
G = {1, 2, 3, 4}
H = {2, 3, 4, 5}
print(G | H) --1,2,3,4,5
print(G - H) --1
print(G & H) --2,3,4
print(G ^ H) --1,5
Control structure: A program structure that manages the execution order of statements (: execution unit for each line)
Structured theorem: A program is made up of a combination of control structures sequential, branch, and iteration.
name ='Yoshiko'; print ('My name is not {}.'. Format (name))-You can write multiple sentences on one line by adding a semicolon at the end of the line.
if conditional expression: --Be careful not to forget the colon if block else: --Be careful not to forget the colon else block
name = input ('Tell me your name >>') print ('{}, nice to meet you.'. Format (name)) food = input (What is'{}'s favorite food? >>'.format (name)) if food =='cake': print ('It's delicious!') else: print ('{} is also good.'. Format (food))
【pass】 if conditional expression: Processing content else: pass--Since empty blocks are not possible in Python, empty blocks can be allowed by "pass"
if'cake' in food: Include any "cake" in --food -- scores = [70, 80, 90, 100] if 100 in scores: --Check if there is "100" in scores -- -- Key name in dictionary name
scores = {'Japanese Language':70, 'Mathmatics':80, 'Science':90, 'Social Studies':100}
key = input ('Please enter the subject name to be added.') if key in scores: --scores to see if there is a key
and: and
or: or
not: Otherwise
if score> = 70 and score <= 100: --70 or more and 100 or less if 70 <= score <= 100: --This way of writing is also possible (but not possible except for Python)
if score <70 or score> 100: --less than 70 or greater than 100 if not (score <70 and score> 100): must be less than --70 and above 100 if not'cake'in food: --if food does not contain "cake"
if conditional expression 1: if block elif conditional expression 2: elif block (Else: #can be omitted else block)
score = int (input ('Please enter your score')) if score < 0 or score > 100: print ('Incorrect input. Please re-enter correctly') elif score >= 70: print ('Pass. Congratulations.') else: print ('Failed. Have a follow-up exam.')
print ('Please answer the question with yes or no.') money = input ('Do you have any money?') if money == 'yes': tight_eat = input ('Do you want to eat a lot?') light_eat = input ('Do you want to eat lightly?')
if tight_eat == 'yes':
print ('How about ramen?') elif light_eat == 'yes': print ('How about a sandwich?') else: print ('Let's eat at home.')
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