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Complete Guide To Arrow: A Python Library for User-friendly Handling Of Dates, Time and Timestamps

aiuniverse — Fri, 19 Mar 2021 06:45:21 +0000

Source – https://analyticsindiamag.com/

Arrow is a flexible Python library designed to create, format, manipulate, and convert dates, time, and timestamps in a sensible and human-friendly manner. It provides an intelligent module API that allows dealing with dates and times with a few code lines and imports. The library is named after the “time’s arrow” concept suggesting the one-directional progress of time. It is inspired by Requests (an HTTP library) and Moment.js (a JavaScript date library).

Why Arrow?

Standard Python library and low-level conventional modules are available for the various date and time functionalities but have the following limitations from a user’s point of view:

Too many modules available such as time, datetime, dateutil, calendar and pytz
A large number of data types to choose from such as datetime, date, time, timedelta, tzinfo and so on
Users may lack experience in handling different time zones
Inefficient ways of timestamps and timezone conversions
Gaps in functionalities such as humanization (e.g. converting a date into human-readable format) and ISO 8601 parsing

Highlighting Features of Arrow

Supports Python 3.6+ versions
A fully-implemented, efficient alternative to datetime standard library
Aware of timezones (uses UTC (Coordinated Universal Time) by default) and enables easy timezone conversion.
Automatic formatting and parsing of strings
Widely supports ISO 8601 standard date and time format.
Supports pytz, ZoneInfo and dateutil objects
Can generate floors, ceilings, spans and ranges for time frames ranging from microseconds to years
Can be extended to users’ own Arrow-derived datatypes
Supports PEP 484-style type hints

Installing Arrow

Install Arrow using pip command as follows:

pip install -U arrow

Practical Implementation

Here’s a demonstration of performing various operations using Arrow. The experiments have been done in Google colab with Python version3.7.10. Explanation of each operation along with its output is as follows:

First, import the Arrow library

import arrow as arw

Represent current time in the given timezone

arw.now()

With no timezone specified, an Arrow object representing current UTC time will be created. Same output results on executing

arw.utcnow()

Output:

To get current time in say US/Pacific timezone:

arw.now(‘US/Pacific’)

Output:

Convert a specified integer or float number into a floating-point UTC timestamp

arw.get(1567900664)

Output:

 #Try with a floating point input
 arw.get(17900664.5463877)

Output:

Verify the converted output here.

String parsing

arw.get('12-03-2020 22:30:25', 'MM-DD-YYYY HH:mm:ss')

Specified date and time will be represented as MM-DD-YYYY HH:mm:ss

format

Output:

Extract date from a string

arw.get('I was born on March 12 1990','MMMM DD YYYY')

‘MMMM DD YYYY’ formatted date will be searched in the string

Output:

Instantiate Arrow object by directly providing a datetime argument

arw.Arrow(2020,12,26)

Output:

Get a datetime representation an Arrow object

x = arw.now()

Suppose, x is

x.datetime

Output: datetime.datetime(2021, 3, 16, 11, 49, 17, 908895, tzinfo=tzlocal())

The components can then be separated as:

x.month

Output: 3

x.year

Output: 2021

x.day

Output: 16

x.hour

Output: 11

Datetime functions can be called to get properties of the Arrow object

x.time()

Output: datetime.time(11, 49, 17, 908895)

Replace one or more components of the Arrow object

a = arw.now()

Suppose, ‘a’ is

a.replace(year=2019, second=45, month=11)

will give the output:

One or more Arrow object attributes can be shifted forward or backward

present = arw.now()

Suppose, ‘present’ object is

Go forward in time by 2 years

present.shift(years=+2)

Output:

Go backward by 4 hours

present.shift(hours=-4)

Output:

Represent date and time in the required format

arw.now().format('HH:MM:SS MM:DD:YYYY')

Output: 12:03:00 03:16:2021

(i.e. 12 hrs 3 mins 00 sec, 16 March 2021)

Convert default UTC to specified timezone

utc = arw.utcnow()

Suppose, utc is

It can be converted to US/Pacific time zone as follows:

utc.to('US/Pacific')

Output:

Humanization examples

Humanize relative to current time:

 future = arw.now().shift(minutes=+2)  #advance by 2 mins
 future.humanize()

Output: ‘in 2 minutes’

Humanize relative to another datetime or Arrow object

 present = arw.now()  #current time
 future = present.shift(days=-3)  #go back by 3 days
 #how far is present from future
 future.humanize(present)

Output: ‘3 days ago’

 #how far is future from present
 present.humanize(future)

Output: ‘in 3 days’

To get only the distance:

future.humanize(present, only_distance=True)

Output: ‘3 days’

Indicate time difference in terms of one or more specific time granularities like hours,

minutes etc.

future.humanize(present, granularity="minute")

Output: ‘4320 minutes ago’ #3 days equals 4320 mins

Multiple granularities can be specified as:

future.humanize(present, granularity=["minute","second"])

Output: ‘in 4320 minutes and 0 seconds’

Get the span of any time unit

arw.now().span(‘minute’)

Output:

 (,
  )

arw.now().span('day') #get the span of time for a whole day

Output:

 (,
  )

Get floor and ceiling values of a specific time component

arw.now().floor('minute')

Output:

arw.now().ceil('minute')

Output:

Get the range of specified timespans

 import datetime
 begin = datetime.datetime(2020, 6, 5, 2, 30) #start time
 end = datetime.datetime(2020, 6, 5, 4, 50)  #end time
 for r in arw.Arrow.range('hour', begin, end):  #iterate in terms of hour
     print(r)

We want time from 2:30 to 4:50 at the interval of an hour so output will contain 2:30, 3:30 and 4:30 times.

Output:

 2020-06-05T02:30:00+00:00
 2020-06-05T03:30:00+00:00
 2020-06-05T04:30:00+00:00

FACTORIES can be used for utilizing Arrow’s module API to create a custom Arrow-derive type.

Suppose, we need to find difference in terms of days between today and the Christmas day. We can define a custom class as:

 class Custom(arw.Arrow):  #pass an Arrow object
      def till_christmas(self):  #define a function for computation
   #store christmas day of given year
          christmas = arw.Arrow(self.year, 12, 25)
 “””
 If given date falls comes after Christmas of that year, compute its difference w.r.t. Christmas of the next year
 “””
          if self > christmas:
              christmas = christmas.shift(years=1)
          return (christmas - self).days  #return the difference

 f = arw.ArrowFactory(Custom) #Create a factory
 x = f.now()  #current date and time

Suppose, x is

Call the till_christmas() method to compute the difference

x.till_christmas()

Output: 283

i.e. Christmas of the year 2021 is 283 days away from 16 March 2021.

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Reptiles rule at Shelley library

aiuniverse — Mon, 10 Jun 2019 10:30:49 +0000

Source:- postregister.com

SHELLEY – Reptiles are amazing — just ask the more than 300 kids, parents and patrons who attended the “Joanna and Friends Reptile Show” Wednesday afternoon at the North Bingham County District Library in Shelley.

Tortoises, snakes and lizards were handled by Tyler and Heather Olsen, with the help of their children — Zodia, Azdyn and Xzavion. Olsen, as master-of-ceremonies, explained some of the characteristics of each animal — what they eat and how they defend themselves.

The one-hour show was as enjoyable as it was educational.

The star of the show is Joanna, a monitor lizard.

“She was named after the lizard in the Disney movie, ‘Rescuers Down Under,’” Olsen said. “These monitor lizards are scavengers. We feed Joanna a turkey meatloaf. We throw in the whole egg, including the egg shell. She gets her calcium from the egg shells. She is like a pet dog; she likes to be held and petted.”

Asked how they started their reptile menagerie, Olsen said, “My kids like unusual animals.”

Some of these animals included the first animal purchased by the Olsen family in 2011. It was a Russian tortoise.

Some of the differences between a tortoise and turtle are a tortoise cannot draw back its head and appendages completely into its shell whereas a turtle can. A tortoise has nails at the end of its feet; a turtle’s feet are webbed. Both species have shells made from keratin, the same material as a person’s fingernails and, yes, a tortoise or turtle can feel when they are petted as a person strokes its shell.

The bearded dragon is from Australia and has spikes for defense.

“The spikes are decoys,” Olsen said. “The dragon has a puffy neck that it blows up for defense. It makes the dragon look a lot bigger. As babies, the dragon eats insects; when it becomes an adult, it is a vegetarian.”

Olsen continued, “Meet our dinosaur. This lizard, named ‘Spike,’ is a Niger Uromastyxs. His tail is his defensive weapon of choice. He will crawl into cracks in the ground and then puff himself up; he uses his tail like a whip. He eats bird seed and beans, legumes. He normally lives in the Sahara Desert and does not drink water; he absorbs humidity from the air. His coloring can be black and yellow, black and orange, or green and purple.”

Mushu, the mangeral monitor lizard, can grow from four to seven feet long. These lizards climb trees and live from 20-30 years. They are strict carnivores and excellent swimmers.

“Lizards and snakes eat their food in one gulp,” Olsen said.

Periwinkle, the white ball python, can grow to six feet long. She is not an albino python; she has white coloring. Her eyes are blue whereas an albino’s eyes are red.

“Ball pythons were popular in ancient Egypt where they were worn as jewelry,” Olsen said. “They are picky eaters; they eat lizards, birds, and some of them can be trained to eat frozen mice.

“If you are interested in making a reptile a pet, know that it’s a longtime commitment,” he said. “Lizards live between 15-20 years, snakes live 15-40 years. Reptiles cannot be domesticated, like a dog or cat. They spend most of their lives in hiding.”

At the conclusion of the show, children and their parents lined up to be able to pet a desert tortoise, two lizards, a ball python, and Joanna, the monitor lizard.

“Pet the animals from their nose to their tail,” Olsen advised.

Parents reported they brought their children to the reptile show so their children could see reptiles.

“I liked all the facts they told us,” one young lady said.

The Joanna and Friends Reptile Show can also be hired for parties. As it says on their card, they can “bring the party animals to you.”

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