PNcheck: Spell checking using ternary search trees
In TSTr: Ternary Search Tree for Auto-Completion and Spell Checking

Description Usage Arguments Details Value See Also Examples

Spell checking using TST and Peter Norvig's approach.

1	PNcheck(tree, string, useUpper = FALSE)

`tree`	a ternary search tree containing the dictionary terms.
`string`	the misspelled string to correct.
`useUpper`	if TRUE, uppercase letters are also used to construct insertions and alterations of the string. Default is FALSE.

The literature on spelling correction claims that around 80% of spelling errors are an edit distance of 1 from the target. For a word of length n, there will be n deletions, n-1 transpositions, 36n alterations, and 36(n+1) insertions, for a total of 74n+35 (of which a few are typically duplicates). PNcheck computes all these variations and search them in a ternary search tree.

For distance 2 the number of variations becomes (74n+35)^2 which makes PNcheck 3 orders of magnitude more expensive than SDcheck.

A vector with the corrected words.

newTree

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2
3

fruitTree <- newTree(c("Apple", "orange", "lemon"))
PNcheck(fruitTree,"lamon")
PNcheck(fruitTree,"apple", useUpper = TRUE)

sh: 1: cannot create /dev/null: Permission denied
sh: 1: wc: Permission denied
Could not detect number of cores, defaulting to 1.
Tree created with 3 words and 16 nodes
[1] "lemon"
[1] "Apple"