[Python for Hikari] Chapter 09-01 Classes (Basics of Objects)

[Python] Chapter 09-01 Object Basics

So far, I have touched on lists and tuples in the fields of strings, numbers, and data structures. As mentioned in the data structure section, these were referred to as ** objects **.

So what is this object? First of all, I would like to explain the object and dig a little deeper.

What is an object?

First, enter the following code in the ** Python Console ** to check it.

>>> S = 'hello'
>>> type(S)
<class 'str'>

I'm assigning the string'hello' to the variable ** S **. Now, next, the ** type () ** function outputs ** \ <class'str' > **. This means that the S variable is currently a ** str type object **.

Now let's take a look at the details of the str object. You can browse from the following URL. https://docs.python.org/ja/3/library/stdtypes.html#text-sequence-type-str

Looking at the manual, the str type is written as a text sequence type. In short, it is a string type object.

Now, if you send the manual a little down, you'll see something called a "string method". For example, let's execute the * str * .capitalize () method at the very beginning. Note that * str * in this manual represents a str type object, so when you actually enter it this time, the variable name will be S.

>>> S
'hello'
>>> S.capitalize()
'Hello'

You can see that only the beginning is capitalized. See the * str * .capitalize () method manual for details.

Also, let's look at other methods. Let's execute the * str * .replace () method.

>>> S.replace('l', 'L')
'heLLo'

You can change the characters in the string with the replace method. See the manual for details.

Let's try various other methods ** while looking at the manual **. In the future, I would like to omit some of the contents written in the manual, except for some parts.

Well, not only this str type, but there are other types of objects. Let's check various people with the following commands.

The following is a ** int type object **.

>>> num1 = 100
>>> type(num1)
<class 'int'>

The following is a ** float type object **.

>>> num2 = 10.5
>>> type(num2)
<class 'float'>

The following is a ** list type object **.

>>> ls = ['Japan', 'America', 'China']
>>> type(ls)
<class 'list'>

The following is a ** tuple type object **.

>>> tp = (10, 20, 30)
>>> type(tp)
<class 'tuple'>

The following is a ** dict type object **.

>>> dc = {'jp':'Japan','us':'America', 'ch':'Chine'}
>>> type(dc)
<class 'dict'>

Each of these types of objects has a ** method **. Let's actually check it. Most of them are listed at the following URL. https://docs.python.org/ja/3/library/stdtypes.html

</ font> In fact, a set of ** data and its behavior (method) ** is generally called an ** object **. For example

>>> ls = [1, 3, 3, 2, 1, 2, 2, 1, 1, 2]
>>> ls.count(2)
4

def calc_func(x):
    print('Run inside a function')
    f = (x ** 2) + (3 * x) + 4
    ##Returns the calculation result f
    return f

print(type(calc_func))