A simple dictionary
|
1
2
|
alien_0
=
{
'color'
:
'green'
,
'point'
:
5
}
print
(alien_0[
'color'
])
#使用大括号
|
The window will show green.
l Using dictionary
n Add key-value pair
For example,
|
1
2
3
4
5
6
|
alien_0
=
{
'color'
:
'green'
,
'point'
:
5
}
print
(alien_0[
'color'
])
alien_0[
'x_position'
]
=
0
alien_0[
'y_position'
]
=
25
print
(alien_0)
|
The window will show
|
1
|
{
'color'
:
'green'
,
'point'
:
5
,
'x_position'
:
0
,
'y_position'
:
25
}
|
-
-
Modify the key-value pair
-
|
1
|
alien_0[
'color'
]
=
'yellow'
|
-
-
Delete the key-value pair
-
Use del is OK.
For example,
|
1
|
del
alien_0[
'points'
]
|
Dictionary will not include points.
-
-
Dictionary just like struct in C language.
-
The dictionary which consists of many objects:
-
For example,
|
1
2
3
4
5
6
7
8
9
10
|
favorite_languages
=
{
'David'
:
'python'
,
'Jane'
:
'java'
,
'John'
:
'C'
,
'Sarah'
:
'ruby'
,
'Michel'
:
'swift'
}
print
(
"David's favorite languages is "
+
favorite_languages[
'David'
].title()
+
"."
)
|
It will show,
|
1
|
David's favorite languages
is
Python.
|
Remember the format!
l Ergodic dictionary
n Ergodic all key-value pairs
Method: items(): items()方法用于返回字典dict的(key，value)元组对的列表
-
-
Ergodic all keys
-
Method: keys():返回字典dict的键列表
For example,
|
1
2
3
4
5
|
for
name
in
favorite_languages.keys():
print
(name.title()
+
"."
)
But
if
we use
for
name
in
favorite_languages:
print
(name.title()
+
"."
)
|
They all have same output.
n Ergodic all values
n Method: values():返回字典dict的值列表
As we all know, the list of value may have same values, then ,how to keep only one value?
We can use set(). For example,
|
1
2
|
for
language
in
set
(favorite_languages.values()):
print
(language.title())
|
n Nesting: 将一系列字典存储在列表中，或将列表作为值存储在字典中，这被称为嵌套。
