Python Fstring formatting

• f - string is the latest python string formatting addition, added in 3.5

  • an f-string is created by prefixing the string with a f e.g.

    f"this is a f-string"

Examples of f-strings

• numbers f'{value:{width}.{precision}f}'

   a= 10.1234
   >>> f'{a:.2f}'
   '10.12'
  
  
  >>> f'{a*1000:,.2f}'
  '10,123.40'
  
  >>> f'{75.765367:.0f}'
  '76'

• date

  >>> f'test-{datetime.datetime.now():%Y-%m-%d_%H:%M:%S}.txt'
  'test-2019-01-29_17:53:37.txt'

• unix date time stamp ( seconds since 1970-01-01 )

  f"{datetime.datetime.utcnow():%s}"

• timestamp with timezone

  import datetime
  tz = datetime.timezone.utc
  ft = "%Y-%m-%dT%H:%M:%S%z"
  t = datetime.datetime.now(tz=tz).strftime(ft)
  print(f"== Summary {t} ==")
  
  == Summary 2020-02-19T22:48:17+0000 ==

• timestamp with specific timezone e.g. 'Pacific/Auckland' +12/+13

  import datetime
  import pytz  # External timezone data, updates often
  
  tz = pytz.timezone('Pacific/Auckland')
  ft = "%Y-%m-%dT%H:%M:%S%z"
  t = datetime.datetime.now(tz=tz).strftime(ft)
  print(f"== Summary {t} ==")
  
  == Summary 2020-02-20T12:04:14+1300 ==