FS Path Tree

A simple class to allow filesystem-style path access to nested dict/list structures, including support for walking "up" the tree with '..'.

Example:

  config = fspathtree()
  config.update( { 'desc' : "example config"
                 , 'time' : { 'N' : 50
                            , 'dt' : 0.01 }
                 , 'grid' : { 'x' : { 'min' : 0
                                    , 'max' : 0.5
                                    , 'N' : 100 }
                            , 'y' : { 'min' : 1
                                    , 'max' : 1.5
                                    , 'N' : 200 }
                            }
                 } )

  # elements are accessed in the same was as a dict.
  assert config['desc'] == "example config"
  # sub-elements can also be accessed the same way.
  assert config['grid']['x']['max'] == 0.5
  # but they can also be accessed using a path.
  assert config['grid/x/max'] == 0.5

  # get a sub-element in the tree.
  x = config['grid/x']

  # again, elements of grid/x are accessed as normal.
  assert x['max'] == 0.5
  # but we can also access elements that are not in this branch.
  assert x['../y/max'] == 1.5
  # or reference elements from the root of the tree.
  assert x['/time/N'] == 50

API

The fspathtree class can be default constructed, with a dict, or with another fspathtree

t1 = fspathtree()
t2 = fspathtree({'one':1})
t3 = fspathtree(t2)

Elements in the tree can be tested for presence using the in operator. They can be accessed with the __call__ operator or the get(...) method.

t = fspathtree({'one':{'two': 2}})

assert '/one/two' in t
assert t['/one/two'] == 2
assert '/one/three' not in t

t['/one/three'] = 3
assert '/one/three' in t
assert t['/one/three'] == 3

assert t.get('/one/three', None) == 3
assert t.get('/one/missing', None) is None

The get_all_paths() method returns a list of all paths in the tree (it actually returns a generator). get_all_leaf_node_paths() returns a list of only leaf node paths. Both accept a predicate that can be used to filer the paths that are returned.

t = fspathtree({'one':{'two': 2}})

paths = list( t.get_all_paths() ) # returns [PathType('/'), PathType('/one'), PathType('two')]
paths = list( t.get_all_leafe_node_paths() ) # returns [PathType('two')]
paths = list( t.get_all_paths(predicate p: p.name == 'one') ) # returns [ PathType('/one')]

Install

You can install the latest release with pip.

$ pip install fspathtree

Or, even better, using pipenv

$ pipenv install fspathtree

Or, even better better, using poetry

$ poetry add fspathtree

Design

The fspathtree is a small wrapper class that can wrap any nested tree data structure. The tree that is wrapped can be accessed with the .tree attribute. This is an improvement over the old fspathdict.pdict class, which stored nodes internally as fspathdict.pdict instances and required "converting" to and from the standard python dict and list types.