Python string formatting - limit string length, but trim string beginning

Question

I'm using Python standard logging module with custom formatter where I limit length of some fields. It uses standard % Python operator.

I can apply limit for percent-formatted string like this (this limits length to 10 chars):

>>> "%.10s" % "Lorem Ipsum"
'Lorem Ipsu'

Is it possible to trim it from the beginning, so the output is 'orem Ipsum' (without manipulating right-side argument)?

Answer 1

Is it possible to trim it from the beginning with % formatting?

Python's % formatting comes from C's printf.

Note that the . indicates precision for a float. That it works on a string is a mere side effect, and unfortunately, there is no provision in the string formatting specification to accommodate stripping a string from the left to a fixed max width.

Therefore if you must strip a string to a fixed width from the end, I recommend to slice from a negative index. This operation is robust, and won't fail if the string is less than 10 chars.

>>> up_to_last_10_slice = slice(-10, None)
>>> 'Lorem Ipsum'[up_to_last_10_slice]
'orem Ipsum'
>>> 'Ipsum'[up_to_last_10_slice]
'Ipsum'

str.format also no help

str.format is of no help here, the width is a minimum width:

>>> '{lorem:>10}'.format(lorem='Lorem Ipsum')
'Lorem Ipsum'
>>> '{lorem:*>10}'.format(lorem='Lorem')
'*****Lorem'

(The asterisk, "*", is the fill character.)

Answer 2

This can easily be done through slicing, so you do not require any string format manipulation to do your JOB

>>> "Lorem Ipsum"[-10:]
'orem Ipsum'