neurokernel.plsel.SelectorParser

class neurokernel.plsel.SelectorParser

This class implements a parser for path-like selectors that can be associated with elements in a sequential data structure such as a Pandas DataFrame; in the latter case, each level of the selector corresponds to a level of a Pandas MultiIndex. An index level may either be a denoted by a string label (e.g., ‘foo’) or a numerical index (e.g., 0, 1, 2); a selector level may additionally be a list of strings (e.g., ‘[foo,bar]’) or integers (e.g., ‘[0,2,4]’) or continuous intervals (e.g., ‘[0:5]’). The ‘*’ symbol matches any value in a level, while a range with an open upper bound (e.g., ‘[5:]’) will match all integers greater than or equal to the lower bound.

Examples of valid selectors include

Selector	Comments
/foo/bar
/foo+/bar	equivalent to /foo/bar
/foo/[qux,bar]
/foo/bar[0]
/foo/bar/[0]	equivalent to /foo/bar[0]
/foo/bar/0	equivalent to /foo/bar[0]
/foo/bar[0,1]
/foo/bar[0:5]
/foo/*/baz
/foo/*/baz[5]
/foo/bar,/baz/qux
(/foo,/bar)+/baz	equivalent to /foo/baz,/bar/baz
/[foo,bar].+/[0:2]	equivalent to /foo[0],/bar[1]

Notes

An empty string is deemed to be a valid selector.

Since there is no need to maintain multiple instances of the lexer/parser used to process path-like selectors, they are associated with the class rather than class instances; likewise, all of the class’ methods are classmethods.

Numerical indices in selectors are assumed to be zero-based. Intervals do not include the end element (i.e., like numpy, not like Pandas).

__init__()

x.__init__(…) initializes x; see help(type(x)) for signature

Methods

p_error(p)
p_level(p)	level : ASTERISK | INTEGER | INTEGER_SET | INTERVAL | STRING | STRING_SET
p_selector_comma_selector(p)	selector : selector COMMA selector
p_selector_dotplus_selector(p)	selector : selector DOTPLUS selector
p_selector_level(p)	selector : level
p_selector_paren_selector(p)	selector : LPAREN selector RPAREN
p_selector_plus_selector(p)	selector : selector PLUS selector
p_selector_selector_level(p)	selector : selector level
p_selector_selector_plus_level(p)	selector : selector PLUS level
pad_parsed(selector[, pad_len, inplace])	Pad token lists in a parsed selector to some maximum length.
parse(selector[, pad_len])	Parse a selector string into tokens.
t_ASTERISK(t)	/*
t_COMMA(t)	,
t_DOTPLUS(t)	.+
t_INTEGER(t)	/?d+
t_INTEGER_SET(t)	/?[(?:d+,?)+]
t_INTERVAL(t)	/?[d*:d*]
t_LPAREN(t)	(
t_PLUS(t)	+
t_RPAREN(t)	)
t_STRING(t)	/[^*/[]():,.d][^+*/[]():,.]*
t_STRING_SET(t)	/?[(?:[^+*/[]():,.d][^+*/[]():,.]*,?)+]
t_error(t)
tokenize(selector)	Tokenize a selector string.

Attributes

lexer
parser
tokens