Converting Between Sequence Formats

Different applications and use cases can require different formats of sequence strings. The page on Sequence String Formats describes what PathSeq accepts as input, and PathSeq outputs to the same format by default. You can output a path sequence to another format by overriding the Formatter class.

Without any changes, the Formatter class will use the default formatting behaviour to format a path sequence into a string.

>>> from pathseq import Formatter, PathSequence
>>>
>>> seq = PathSequence("image.1-5#.exr")
>>> str(seq)
'image.1-5#.exr'
>>> Formatter().format(seq.parsed)
'image.1-5#.exr'

To convert to another format, the methods of a Formatter can be overriden. For example, a basic formatter for Houdini strings might look like this:

>>> class MyHoudiniFormatter(Formatter):
...   def range(self, range_):
...       return "$F"
...
>>> seq = PathSequence("image.1-5#.exr")
>>> MyHoudiniFormatter().format(seq.parsed)
'image.$F.exr'

There is a method on the Formatter for each attribute on a parsed sequence. So any part of a path sequence can be changed.

>>> class DemoFormatter(Formatter):
...     def stem(self, stem):
...         return "stem"
...     def pre_range(self, pre_range):
...         return "|pre_range"
...     def range(self, range_):
...         return "|range"
...     def inter_range(self, inter_range):
...         return "|inter_range"
...     def post_range(self, post_range):
...         return "|post_range"
...     def suffixes(self, suffixes):
...         return "|suffixes"
...
>>> seq = PathSequence("image.1-5#.exr")
>>> DemoFormatter().format(seq.parsed)
'stem|pre_range|range|suffixes'

The order of the parts in a loose can even be changed by overriding the format() or ranges() methods. For example, a naive formatter to convert a loose format range into a simple might look like this:

>>> class ToSimpleFormatter(Formatter):
...     def format(self, seq):
...         return (
...             self.stem(seq.stem)
...             + self.pre_range(seq.pre_range or ".")
...             + self.ranges(seq.ranges)
...             + self.suffixes(seq.suffixes)
...         )
...
>>> seq = LoosePathSequence("1-5#image.exr")
>>> ToSimpleFormatter().format(seq.parsed)
'image.1-5#.exr'