Yaml file, ultra-detailed explanation

YAML file brief

YAML is a very high readability, and programming language data structures are very close. Along with rich expression and scalable, and easy to use data markup language.
YAML full name is actually "YAML Is not a Markup Language" (YAML is not a markup language) is a recursive acronym, it is emphasized that the data itself, rather than focusing mark

Why use YAML file?

In fact, YAML file is also a configuration file, but compared to the ini, conf configuration file, the more simple, easy to operate, but also to store different types of data; and like ini values are stored on the string type, read even after taking manual conversion

The basic syntax rules of YAML

Case Sensitive
Use indention hierarchy
Not allowed to use the Tab key to indent, only spaces are allowed . (Your ide the tab key output may be replaced by four spaces)
The number of spaces to indent does not matter, as long as the left elements are aligned to the same level
# Denotes a comment

YAML support data structures

Object: a set of keys, also known as mapping (mapping) / hashes (hashes) / Dictionary (dictionary)
Array: a set of values are arranged in order, also known sequence (sequence) / list (list)
Scalar (scalars): individual, can not be divided value

YAML, object data type

A set of key-value object of using the structure represented by colons.

animal: dogs

Python is converted into a data structure, as follows:

{'animal': 'dogs'}

All key-value pairs assignment.

hash: { name: Steve, foo: bar }

Python is converted into a data structure, as follows:

{'hash': {'name': 'Steve', 'foo': 'bar'}}

The list assignment

lists : [1,2,3]

Python is converted into a data structure, as follows:

{'lists': [1, 2, 3]}

Tuple assignment

tuples : (1,2,3)

Python is converted into a data structure, as follows:

{'tuples': '(1,2,3)'}

to sum up

When the list of assignments, key-value pair data structure is converted into the Python directly when the list, using the dictionary;,
When the assignment element group, the string is converted
The final output is a dictionary, you can get the corresponding key values

YAML, array

Here that the structure of the array with [1,2,3,4] are not the same, as follows:

cool_list:
  - 10
  - 15
  - 12

hard_list:
  - {key: value}
  - [1,2,3]
  - test:
      - 1
      - 2
      - 3

twice_list:
  -
    - {a: b}
    - {c: d}
    - {e: f}

Python is converted into a data structure, as follows:

'cool_list': [10, 15, 12], 
'hard_list': [
    {'key': 'value'}, 
    [1, 2, 3], 
    {
        'test': [1, 2, 3]
    }
],
'twice_list': [
    [
        {'a': 'b'}, 
        {'c': 'd'}, 
        {'e': 'f'}
    ]
]

to sum up

When you wrote the following such a data structure, will automatically turn into a dictionary, such as: { ' Key ' : ' value, val2 ' }

key:
    value,val2

Yamla, 纯量

Scalar is the most basic, the value can not be divided; substantially similar data types

String
Boolean value
Integer
Float
time
date
Null

int: 12
float: 12.3
string: pets
bool: true
None: null
time: 2001-12-14t21:59:43.10-05:00
date: 2018-03-21

Results of the

{
   'int': 12, 
   'float': 12.3, 
   'string': 'pets', 
   'bool': True, 
   'None': None, 
   'time': datetime.datetime(2001, 12, 14, 21, 59, 43, 100000, tzinfo=datetime.timezone(datetime.timedelta(days=-1, seconds=68400))), 
   'date': datetime.date(2018, 3, 21)
}

It includes knowledge

ISO 8601 format used between the time, date, and time using a T-connector, on behalf of the last used time zone +
Date must be in ISO 8601 format, i.e. yyyy-MM-dd
bool type: true, True, false, False can
Can ~ represent null

YAML, string Comments

String is the most complicated, but it is the most common data type.
Default string without using quotation marks '' '' wrapped

The basis of the wording

str: This is his string

Python is converted into a data structure, as follows:

{ ' STR ' : ' What is his string ' }

Use quotation marks under what circumstances? When the string contains spaces or special characters , etc.

str_s: " string contains special characters, spaces & @ # $% ^ & * ()! "

Python is converted into a data structure, as follows:

{ ' Str_s ' : ' string that contains spaces & special characters @ # $% ^ & * ()! ' }

Note that double quotes "" does not escape special characters

str1: 'test\n1'
str2: "test\n2"

Python is converted into a data structure, as follows:

{'str1': 'test\\n1', 'str2': 'test\n2'}

Can split multiple lines, each line is a space, but be aware that their level must be consistent

st_string: hello
           world

Python is converted into a data structure, as follows:

{
   'st_string': 'hello world'
}

YAML, type a strong turn

YAML allows two exclamation points, cast data types

is: !!str 123
sf: !!float '12.22'
si: !!int '222'

Execution results are as follows

{
  'is': '123', 
  'sf': 12.22, 
  'si': 222
}