Basics of Python ①

I've been in the Ai classroom lately I will write a summary.

Basics

output

The unspoken output. The quotes used can be single or double

print('Hello World')

Enter a comment

#comment

Calculation

It can be calculated as follows. You can use it like this

・ Addition: "+" ·subtraction:"-" ·multiplication:"*" ·division:"/" ・ Calculation of remainder: "%" ・ Exponentiation: "**"

print(3+6)
#Output result
9

String

If you enclose it in quotation marks It will be a character string.

print('3+6')
#Output result
3+6

variable

Next, the basic variables

Variable basics

n = 3
#n is the variable name, 3 is the value to enter
print(n)
#3 and output
print(n+5)
#It can be calculated in the same way, and 8 is output.

The following 3 points can be used

• Half-width alphabet (uppercase and lowercase)
• Half-width numbers
• _(underscore)

The ones that cannot be used are as follows

• Numbers cannot be used as the first letter
• Defined function name (print, list, etc.)
• The same character string as reserved words and keywords Reserved words are like the grammar used in Python programs, and there are 33 types such as "if", "for", "True", and "False".

important point

It's not unusable, but Japanese is OK But not very popular as a definition

If it turns out after it works

Delete it in the following form.

del variable name

Linking

You can connect as follows.

n = "Tanaka"
print("Name is" + n + "is")

##output:The name is Tanaka.

Mold

There are types such as letters and numbers. The types are as follows

str type: string int type: integer float type: floating point

When you want to know the type

print(type(Variable name))

age = 17
print(type(age))  #When you want to know the type of age

#Output result
<class 'int'>

Type conversion

If you try to connect with different types An error will occur, so convert as follows.

str (): Convert to string int (): Convert to integer value float (): Convert to numeric type including decimal point

height = 150
print("How tall are you" + str(height) + "cm.")

if statement

Comparison operator

Write as below and return true or falsa.

a == b # a and b are equal a! = b # a is not equal to b (inverted) a> b # a is greater than b a> = b # a is greater than or equal to b a <b # a is less than b a <= b # a is less than or equal to b

use example of if

if: Executes the following processing that is 4 indented when the conditions on the left are met. else: Execute if if and elif do not hold elif: Write if you want to process and condition separately between if and else.

Can be executed with only basic if Added else and elif in some cases

n = 2
if n == 1: #If n is equal to 1, perform the following processing
    print("This is the first process.") 
elif n == 2: #If n is equal to 2, perform the following processing
    print("This is the second process.") 
elif n == 3: #If n is equal to 3, perform the following processing
    print("This is the third process.") 
else: #If all the above three conditional expressions are not satisfied, the following processing is performed.
    print("This is the fourth and subsequent processes.")

Boolean operator (and ・ or ・ not)

Conditional expression A and conditional expression B # If both conditional expressions of A and B are True, processing is performed. Conditional expression A or conditional expression B # If either conditional expression is True, processing is performed. not Conditional expression # Returns False when the conditional expression is True, True when the conditional expression is False.

Example of use

n_1 = 15
n_2 = 29

print(n_1 > 8 and n_1 < 14)
# true
 
print(not n_1 ** 2 < n_2 * 5)
# true