Details
Filter Grammar - Regular Expressions in Filters
You can apply a regular expression to any filter variable that is a String data type.
You can return whether a regex matches: /<regex>/.test(<variable>)
- /DF\d\d\d\d/.test(sample_name)// Returns true if the view's sample name matches the regex DF\d\d\d\d.
You can also use a capture string and compare the captured string to another string: /<regex(capture)>/.extract(<variable>), which returns the captured string.
- /DF(\d\d\d\d)/.extract(sample_name) = '1234'// Captures the four digits from the regex and tests against '1234'.
Note:
The examples above use the view-level variable sample_name, which evaluates to a String. If you attempt to use a String data type axis variable, those variables may evaluate to a vector of strings, since there may be multiple instances of the axis variable within a single view. In this case, the regex must be applied within the axis filter, as shown below:
match[/FH\d\d\d\d/.test(feature_string)]// For this expression, the regex is applied for each match's feature_string. If any of the matches' feature_string match the regex, the view will be included.
The following is an example of an invalid regex filter expression:
/FH\d\d\d\d/.test (match/feature_string)// The expression should return true if the view includes a match with a feature_string matching the regex. However, this is invalid, because each view may have multiple matches.
- You cannot use the sets variable in a regular expression.
Writing Filter Expressions
Filter expressions can include view-level filters where the variable refers to the entire view.
- filename ~ 'REJECT'// Returns views where filename contains 'REJECT'.
- count(feature) > 3// Returns views with more than three features.
Filter expressions can also include axis filters, where the individual marking or labeling for each view is evaluated.
- feature [score > 0.5 ]// Returns views with a feature with score greater than 0.5.
You can combine view-level and axis-level filters.
- filename ~ 'REJECT' and feature [score > 0.5 ]// Returns views where filename contains 'REJECT' and a feature scoring greater than 0.5.
You can combine filters for multiple axes.
- feature [score > 0.5 ] and match [ score > 0.5 ]// Returns views with a feature with score greater than 0.5 and a match with a score greater than 0.5.
You can specify multiple filter conditions for an axis.
- feature[score > 0.5 and matched ]// Returns views with a feature with a score greater than 0.5 and the feature is in a matched model.
