em

Modified EM (Ewing-Millett) notation.

The basic notation is given as a dictionary of nodes, where each node’s value is a list of tuples in CCW order representing the adjacent node and the position of the arc in the adjacent node. This notation should be used as a default notation, since it is the most similar to the native class structure.

Example:

The graph

C

/ A—B—D

is encoded by the notation {A:[(B,0),(C,1)], B:[(A,0),(D,0),(C,0)], C:[(B,2),(A,1)], D:[(B,1)]}, and the condensed notation is assuming lower case letters for nodes: “b0c1,a0d0c0,b2a1,b1”. In the case of knotted graphs, … In the case of oriented knots, …

See “Ewing, B. & Millett, K. C. in The mathematical heritage of CF Gauss 225–266 (World Scientific, 1991)”.

Functions

from_condensed_em_notation(data[, ...])	Convert a condensed EM string to a planar diagram.
from_em_notation(data[, create_using])	param data: dictionary of lists of tuples or a string that evaluates to this
to_condensed_em_notation(g[, separator])	Return EM code of g as a condensed string.
to_em_notation(g)	Returns EM code of planar diagram.