The examples in this article describe the Python mapping list. Share to everyone for your reference. The specific analysis is as follows:
List mapping is a very useful way to transform data by applying a function to each element of the list, and you can use a strategy or method to traverse the calculation of each element.
For example:
Copy the Code code as follows:
params = {"Server": "Mpilgrim", \
"Database": "Master", \
"UID": "sa", \
"PWD": "Secret" \
}
Print ["%s=%s"% (k, params[k]) for K in Params.keys ()]
print '; '. Join (["%s=%s"% (k, params[k]) for K in Params.keys ()])
The returned result is:
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[' Uid=sa ', ' pwd=secret ', ' database=master ', ' Server=mpilgrim ']
It can also be improved by converting tuples into strings, using the Join function method.
Copy CodeThe code is as follows:
' Uid=sa;pwd=secret;database=master;server=mpilgrim '
(the Join function is not only used for tuples but also for lists, functions are strings)
Split with join instead, convert string to Narimoto Group
See the following applications
Copy CodeThe code is as follows:
str = ' Server=mpilgrim;uid=sa;database=master;pwd=secret '>>> Str.split (';')
[' Server=mpilgrim ', ' uid=sa ', ' database=master ', ' Pwd=secret ']
>>> str.split ('; ', 1)
[' Server=mpilgrim ', ' Uid=sa;database=master;pwd=secret ']
>>> str.split ('; ', 2)
[' Server=mpilgrim ', ' uid=sa ', ' Database=master;pwd=secret ']
List map Use cases:
Copy the Code code as follows:
>>>> Li = [1, 9, 8, 4]
>>> [elem*2 for Elem in Li] 1
[2, 18, 16, 8]
>>> Li
[1, 9, 8, 4]
Hopefully this article will help you with Python programming.
