relentless.collections.PairMatrix

class relentless.collections.PairMatrix(keys, default=None)

Generic matrix of values per-pair.

Defines a symmetric matrix of parameters corresponding to (i,j) pairs. The matrix is essentially a dictionary of dictionaries, keyed on (i,j). There is an equivalent virtual entry for (j,i). (The pairs that are actually saved have j >= i.) The dictionary associated with each pair can have any number of entries in it, although a common use case is to have the same parameter stored per-pair.

The pairs in the matrix are frozen from the list of types specified when the object is constructed. It is an error to access pairs that cannot be formed from types.

The pair matrix emulates a dictionary, and its pairs are iterable.

Parameters:

types (array_like) – List of types (A type must be a str).

Raises:

• ValueError – If initialization occurs with empty types.

• TypeError – If types does not consist of only strings.

Examples

Create a pair matrix:

m = PairMatrix(types=('A','B'))

Set a pair matrix value:

m['A','A']['energy'] = 1.0
m['A','B']['energy'] = -1.0
m['B','B']['energy'] = 1.0

Get a pair matrix value:

>>> m['A','A']['energy']
1.0
>>> m['A','B']['energy']
-1.0
>>> m['B','A']['energy']
-1.0

Iterate a pair matrix:

for pair in m:
    m[pair]['mass'] = 1.0

Multiple parameters are a dictionary:

>>> m['A','B']
{'energy': -1.0, 'mass': 1.0}

Single-type matrix still needs types as a tuple:

PairMatrix(types=('A',))

Methods

clear()	Clear entries in the dictionary, resetting to default.
get(k[,d])
items()
keys()
pop(k[,d])	If key is not found, d is returned if given, otherwise KeyError is raised.
popitem()	as a 2-tuple; but raise KeyError if D is empty.
setdefault(k[,d])
update([E, ]**F)	If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v
values()

clear()

Clear entries in the dictionary, resetting to default.

get(k[, d]) → D[k] if k in D, else d.  d defaults to None.

items() → a set-like object providing a view on D's items

keys() → a set-like object providing a view on D's keys

pop(k[, d]) → v, remove specified key and return the corresponding value.

If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair

as a 2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D

update([E, ]**F) → None.  Update D from mapping/iterable E and F.

If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D's values