Regular expressions allow users to create complicated queries. Below follows a list of most commonly used regular expressions together with explanations and some potential uses.
[abc] means "a or b or c", e.g. query "[br]ang" will match both "adbarnirrang" and "bang"
[^abc] means "begins with any character but a,b,c", e.g. query [^aeou]ang will match "rang" but not "baang"
[a-zA-Z] means "a charater from a/A through z/Z", e.g. b[a-zA-Z] will match "bang", "bLang" or "baang" but not "b8ng"
. (the dot) means "any character", e.g. "b.ng" will match "bang", "b8ng", but not "baang"
X* means "X zero or more times", e.g. "ba*ng" will match "bng", "bang", "baang", "baaang" etc.
X+ means "X one or more time", e.g. "ba+ng" will match "bang", "baang" but not "bng"
^ means "the beginning of the annotation", e.g. "^ng" will match "ngabi" but not "bukung"
$ means "the end of the annotation", e.g. "ung$" will match "bukung" but not "ngabi"
Examples
^[pbtd][^aeiou]
You can use this expression to search for complex onsets. It will find words that start with one of the plosives ("p","b","t","d") followed by a character that is not a vowel ("a","e","i","o","u"). An example of a matching word is "tsakeha"
[^n]g$
You can use this expression in case you want to search for annotations ending with a "g", but not with "ng". In Dutch, you will find "snelweg" and "maandag" as the results but not words as "bang".
^k.+k$
You can use this expression if you want to search for annotation starting and ending with "k" and with one or more character between them, e.g. "kitik" or "kanak-kanak"
^(.+)\1$
You can use this expression to search for words that are reduplicated. When you put something in bracketes, you create a variable (.+), which you can refer to as "\1". This expression then searches for an annotation that starts with one or more random characters followed by that same sequence of characters. This expression will match for instance "kulukulu".
More about regular expressions...
The following tables have been created by a user of ELAN (an annotation tool which has the same search mechanism as TROVA). They may result quite useful also for other users since they offer a simple and clear overview of the main symbols (partly different from the ones just seen) used in regular expressions, with a short explanation and an example for each of them. Bear in mind that the examples are taken from the language that the user is being researching, so do not pay attention to the meaning of the words but to the working mechanism of the regular expressions.
Table 1.1. Symbols
| Symbols | Place | Meaning |
|---|---|---|
| \b | at the beginning and/or end of a string | word boundary |
| \w+ | at the end of a string | variable end of word |
| . | anywhere | any letter |
| .* | between spaces | any string of letters between spaces/any word |
| .*\ | between spaces | any string of words |
| (x|y) | anywhere | either x or y |
| [^x] | place at the beginning | not x |
| (....)\l | anywhere | words with four reduplicated letters |
| ? | after a letter | the preceding letter is optional |
Table 1.2. Search for particular word forms (examples)
| Symbols | Hits | Examples |
|---|---|---|
| sa | all words containing the string sa | sa, vasaku, sahata, tisa |
| \bsa | all words starting with sa | sa, sahata, sana; NOT vasaku, tisa |
| \bsa\b | all words sa | sa |
| \bsa..\b | all words consisting of sa + two letters that follow sa | saka, saku, sana |
| \bsa\w+ | all words beginning with sa, but not the word sa by itself | sahata, sana |
| \b.*ana\b | al words ending in ana | sinana, tamuana, sana, bana, maana |
| (....)\l | all words with four reduplicated letters | pakupaku, vapakupaku, mahumahun, vamahumahun |
| \b(....)\l | all words beginning with four reduplicated letters | pakupaku; NOT vapakupaku |
| \b(....)\lana\b | all words beginning with four reduplicated letters and ending in ana | vasuvasuana, hunuhunuana |
| \bva(....)\l | all words consisting of the prefix va- + four reduplicated letters | vapakupaku, vagunagunaha |
| \bvahaa?\b | all tokens of vahaa and vaha | vahaa and vaha |
Table 1.3. Search for particular sequences of words (examples)
| Symbols | Hits | Examples |
|---|---|---|
| \bsaka\b .* \bhaa | string of 3 words: (1) saka; (2) any word; (3) the word haa by itself or with suffixes | saka antee haa; saka abana haari; saka kabuu haana |
| saka .* \bhaa\w+ | string of 3 words: (1) saka; (2) any word; (3) a word beginning with haa, but NOT the word haa by itself | saka abana haari; saka kabuu haana |
| (\bsaka\b|\bsa\b) \bpaku\b | 2-word string consisting of saka or sa and paku | saka paku; sa paku |
| (\bsaka\b|\bsa\b) .* \bvaha\b | strings of 3 words: (1) saka or sa; (2) any word; (3) vaha | saka tii vaha; sa tapaku vaha |
| (\bsaka\b|\bsa\b) (....)\l \bhaa | strings of 3 words: (1) saka or sa; (2) any word with four reduplicated letters; (3) the word haa or a word beginning with haa | sa natanata haa; saka natanata haana |