Python

参考内容 Dive into python
参考内容 Runoob 教程

0. Installing python

1. Function

1.1 First python program

SUFFIXES = {1000: ['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
1024: ['KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB']}

def approximate_size(size, a_kilobyte_is_1024_bytes=True):

    '''Convert a file size to human-readable form.
    Keyword arguments:

    size -- file size in bytes
    a_kilobyte_is_1024_bytes -- if True (default), use multiples of 1024
    if False, use multiples of 1000

    Returns: string
    '''
    if size < 0:
    raise ValueError('number must be non-negative')
    multiple = 1024 if a_kilobyte_is_1024_bytes else 1000
    for suffix in SUFFIXES[multiple]:
        size /= multiple
        if size < multiple:
            return '{0:.1f} {1}'.format(size, suffix)
    raise ValueError('number too large')

if __name__ == '__main__':
    print(approximate_size(1000000000000, False))
    print(approximate_size(1000000000000))

function format:

def func_name(var1, var2 = v2, *args, **kargs)
    '''
    fun.__doc__
    '''
    Your code here

    return value

Note:

1. Use ''' ''' to include instruction of functions, which is shown in fun.__doc__
2. The fun.__name__ is __main__ Only when the program is being executed, it will not be executed when be imported
3. Python use tab to promise a block, not end or {}
4. *args likes a tuple, passing par values
5. **kargs likes a dic, passing key values and names
6. func.__self__

Everything is object:
Use type() or .type to view the class of variable.

1. SUFFIXES: dictionary
2. SUFFIXES[index]: list
3. approximate_size: function
4. print: built-in function

Variables:

>>> from humansize import approximate_size
>>> approximate_size(4000, a_kilobyte_is_1024_bytes=False)
'4.0 KB'
>>> approximate_size(size=4000, a_kilobyte_is_1024_bytes=False)
'4.0 KB'
>>> approximate_size(a_kilobyte_is_1024_bytes=False, size=4000)
'4.0 KB'
>>> approximate_size(a_kilobyte_is_1024_bytes=False, 4000)
File "<stdin>", line 1
SyntaxError: non-keyword arg after keyword arg
>>> approximate_size(size=4000, False)
File "<stdin>", line 1
SyntaxError: non-keyword arg after keyword arg

As soon as you have a named argument, all arguments to the right of that need to be named arguments, too.

2. Datatype