学习pyyaml

网上查了一圈，觉得较好的yaml教程有：

YAML 语言教程 ：http://www.ruanyifeng.com/blog/2016/07/yaml.html。

另外，在github的pyyaml库中找到一个示例：

 

#
# Examples from the Preview section of the YAML specification
# (http://yaml.org/spec/1.2/#Preview)
#

# Sequence of scalars 数组
---
- Mark McGwire
- Sammy Sosa
- Ken Griffey

# Mapping scalars to scalars 字典
---
hr:  65    # Home runs
avg: 0.278 # Batting average
rbi: 147   # Runs Batted In

# Mapping scalars to sequences 键为字符串，值为数组的字典
---
american:
  - Boston Red Sox
  - Detroit Tigers
  - New York Yankees
national:
  - New York Mets
  - Chicago Cubs
  - Atlanta Braves

# Sequence of mappings 项为字典的数组
---
-
  name: Mark McGwire
  hr:   65
  avg:  0.278
-
  name: Sammy Sosa
  hr:   63
  avg:  0.288

# Sequence of sequences 项为数组的数组
---
- [name        , hr, avg  ]
- [Mark McGwire, 65, 0.278]
- [Sammy Sosa  , 63, 0.288]

# Mapping of mappings 字典套构
---
Mark McGwire: {hr: 65, avg: 0.278}
Sammy Sosa: {
    hr: 63,
    avg: 0.288
  }

# Two documents in a stream
--- # Ranking of 1998 home runs
- Mark McGwire
- Sammy Sosa
- Ken Griffey
--- # Team ranking
- Chicago Cubs
- St Louis Cardinals

# Documents with the end indicator
---
time: 20:03:20
player: Sammy Sosa
action: strike (miss)
...
---
time: 20:03:47
player: Sammy Sosa
action: grand slam
...

# Comments
---
hr: # 1998 hr ranking
  - Mark McGwire
  - Sammy Sosa
rbi:
  # 1998 rbi ranking
  - Sammy Sosa
  - Ken Griffey

# Anchors and aliases
---
hr:
  - Mark McGwire
  # Following node labeled SS
  - &SS Sammy Sosa
rbi:
  - *SS # Subsequent occurrence
  - Ken Griffey

# Mapping between sequences
---
? - Detroit Tigers
  - Chicago cubs
:
  - 2001-07-23
? [ New York Yankees,
    Atlanta Braves ]
: [ 2001-07-02, 2001-08-12,
    2001-08-14 ]

# Inline nested mapping
---
# products purchased
- item    : Super Hoop
  quantity: 1
- item    : Basketball
  quantity: 4
- item    : Big Shoes
  quantity: 1

# Literal scalars
--- | # ASCII art
  //||/||
  // ||  ||__

# Folded scalars
--- >
  Mark McGwire's
  year was crippled
  by a knee injury.

# Preserved indented block in a folded scalar
---
>
 Sammy Sosa completed another
 fine season with great stats.

   63 Home Runs
   0.288 Batting Average

 What a year!

# Indentation determines scope
---
name: Mark McGwire
accomplishment: >
  Mark set a major league
  home run record in 1998.
stats: |
  65 Home Runs
  0.278 Batting Average
# Quoted scalars
---
unicode: "Sosa did fine.u263A"
control: "1998	1999	2000
"
hex esc: "x0dx0a is 
"
single: '"Howdy!" he cried.'
quoted: ' # not a ''comment''.'
tie-fighter: '|-*-/|'

# Multi-line flow scalars
---
plain:
  This unquoted scalar
  spans many lines.
quoted: "So does this
  quoted scalar.
"

# Integers
---
canonical: 12345
decimal: +12_345
sexagesimal: 3:25:45
octal: 014
hexadecimal: 0xC

# Floating point
---
canonical: 1.23015e+3
exponential: 12.3015e+02
sexagesimal: 20:30.15
fixed: 1_230.15
negative infinity: -.inf
not a number: .NaN

# Miscellaneous
---
null: ~
true: boolean
false: boolean
string: '12345'

# Timestamps
---
canonical: 2001-12-15T02:59:43.1Z
iso8601: 2001-12-14t21:59:43.10-05:00
spaced: 2001-12-14 21:59:43.10 -5
date: 2002-12-14

# Various explicit tags
---
not-date: !!str 2002-04-28
picture: !!binary |
 R0lGODlhDAAMAIQAAP//9/X
 17unp5WZmZgAAAOfn515eXv
 Pz7Y6OjuDg4J+fn5OTk6enp
 56enmleECcgggoBADs=
application specific tag: !something |
 The semantics of the tag
 above may be different for
 different documents.
# Global tags
%TAG ! tag:clarkevans.com,2002:
--- !shape
  # Use the ! handle for presenting
  # tag:clarkevans.com,2002:circle
- !circle
  center: &ORIGIN {x: 73, y: 129}
  radius: 7
- !line
  start: *ORIGIN
  finish: { x: 89, y: 102 }
- !label
  start: *ORIGIN
  color: 0xFFEEBB
  text: Pretty vector drawing.

# Unordered sets
--- !!set
# sets are represented as a
# mapping where each key is
# associated with the empty string
? Mark McGwire
? Sammy Sosa
? Ken Griff

# Ordered mappings
--- !!omap
# ordered maps are represented as
# a sequence of mappings, with
# each mapping having one key
- Mark McGwire: 65
- Sammy Sosa: 63
- Ken Griffy: 58

# Full length example
--- !<tag:clarkevans.com,2002:invoice>
invoice: 34843
date   : 2001-01-23
bill-to: &id001
    given  : Chris
    family : Dumars
    address:
        lines: |
            458 Walkman Dr.
            Suite #292
        city    : Royal Oak
        state   : MI
        postal  : 48046
ship-to: *id001
product:
    - sku         : BL394D
      quantity    : 4
      description : Basketball
      price       : 450.00
    - sku         : BL4438H
      quantity    : 1
      description : Super Hoop
      price       : 2392.00
tax  : 251.42
total: 4443.52
comments:
    Late afternoon is best.
    Backup contact is Nancy
    Billsmer @ 338-4338.

# Another full-length example
---
Time: 2001-11-23 15:01:42 -5
User: ed
Warning:
  This is an error message
  for the log file
---
Time: 2001-11-23 15:02:31 -5
User: ed
Warning:
  A slightly different error
  message.
---
Date: 2001-11-23 15:03:17 -5
User: ed
Fatal:
  Unknown variable "bar"
Stack:
  - file: TopClass.py
    line: 23
    code: |
      x = MoreObject("345
")
  - file: MoreClass.py
    line: 58
    code: |-
      foo = bar

 

英文不太好，很多不太会翻译。就不误导别人了，见谅。