shijian 2016.1.12.1720

change and time utilities

shijian

Python change and time functions

usage

time expressions

Function style_datetime_object accepts a datetime object and returns a string representation of a time. The default style is “YYYY-MM-DDTHHMMSS” and it can be changed by argument. Styles available are as follows:

time representation	comment
YYYY-MM-DDTHHMMSSZ	filename safe (default)
YYYY-MM-DDTHHMMSSMMMMMMZ	microseconds
YYYY-MM-DD HH:MM:SS UTC	elegant
UNIX time S.SSSSSS	UNIX time in seconds with second fraction
UNIX time S	UNIX time in seconds rounded

Functions time_UTC and time_UNIX are sorts of special cases of function style_datetime_object which return representations of the current time (as opposed to any specified datetime object) in a style. For time_UTC, the default style is “YYYY-MM-DDTHHMMSS” and for time_UNIX, the default style is “UNIX time S” and these styles can be changed by argument.

>>> shijian.time_UTC()
'2015-01-05T092125Z'
>>> shijian.time_UNIX()
1420449720

unique identifiers

Function propose_filename proposes a safe filename. It can accept a filename suggestion or, by default, can generate its own filename suggestion, a time expression returned by function time_UTC. Filename suggestions are tested and then proposed if they meet test conditions. The default condition is to not overwrite existing files and to append an underscore followed by an integer in order to meet this condition.

>python
Python 2.7.6 (default, Mar 22 2014, 22:59:56)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import shijian
>>> shijian.propose_filename()
'2015-01-05T092319Z'
>>> shijian.propose_filename(filename = "data.pkl")
'data.pkl'
>>>
>touch data.pkl
>python
Python 2.7.6 (default, Mar 22 2014, 22:59:56)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import shijian
>>> shijian.propose_filename(filename = "data.pkl")
'data_1.pkl'

Function UID returns a 128 bit integer unique identifier in hexadecimal with dashes in accordance with RFC 4122 UUID version 4.

>>> shijian.UID()
'91df3b90-285c-4f22-8ced-a154b3b5b09b'
>>> shijian.UID()
'169bde88-2be2-4b46-bf2d-5bb7aee85658'

Function unique_number returns an integer that does not exist in a global list of integers recorded by the function.

>>> shijian.unique_number()
1
>>> shijian.unique_number()
2

Function unique_3_digit_number returns an integer of 3 significant figures that does not exist in a global list of integers of 3 significant figures recorded by the function.

>>> shijian.unique_3_digit_number()
100
>>> shijian.unique_3_digit_number()
101

clocks

Clocks can be created in a straightforward way such as the following:

alpha = shijian.Clock(name = "alpha")

By default, clocks keep time from their creation time. This behaviour can be disabled using Boolean argument start = False. Clocks can be assigned a name or can generate their own unique identifier. Clocks can be stopped easily:

beta.stop()

and can be started easily:

alpha.start()

Clocks can report on their characteristics in ways such as the following:

print(alpha.name())
print(alpha.start_time())
print(alpha.stop_time())
print(alpha.time())

Clocks can also provide a general printout of their characteristics:

alpha.printout()

All clocks are recorded in the shijian list of clocks. Printouts of clocks are available in two styles: full and statistics. The style “full” returns the elapsed times of all clocks while the default style “statistics” returns the mean times of all clocks of the same name.

shijian.clocks.printout(style = "full")
shijian.clocks.printout()

filename sequences

The function natural_sort naturally sorts a list. The function find_file_sequences, for which a directory and file extension can be specified, returns a naturally-sorted list of filenames that are in a sequence or returns a dictionary of lists of filenames that are in a sequence. For example, a list something like the following could be returned:

['image-000001.png', 'image-000002.png', 'image-000003.png', 'image-000004.png', 'image-000005.png']