VisFlow Attribute Filter
examines attribute values of data items and perform attribute filtering.Filter Types
An attribute filter works in one of the four types. The filter type can be configured via Filter Type. For all filter types, Column must be specified. Filtering is based on attribute values from that column.
Pattern Filter
A pattern filter keeps the data items that match the given patterns. Each pattern is a string or a regular expression. Choose a Mode to define how patterns are matched against:
Range Filter
A range filter keeps the data items that have an attribute value within a given range. Specify the range using Min and Max.
Range endpoints may be giving using constants input. The first constant is used as Min, and the second is used as Max. The remaining constants have no effect.
Extremum Filter
An extremum filter finds the data items that have the maximum or minimum value(s) in the filtered column. Use Criterion to choose from a Maximum or a Minimum filter.
See Amount Type, Amount, Group By Column and Distinct Values for other configurations related to extremum filter.
Sampling
A sampling filter samples the data items. Sampling can either reduce the amount of data to a fixed Count or a certain Percentage.
See Amount Type, Amount, Group By Column, and Distinct Values for other configurations related to sampling filter.
Comparator
The attribute filter chooses a comparator automatically based on the column type of the input data. Strings are compared by lexicographical order. Dates are compared by their POSIX values. Otherwise a numerical comparator is used.
A pattern filter always converts values to strings and uses string comparators.
Options
Filter Type
Configures the filter type used. See filter types.
Column
Configures the column on which filtering is applied.
Mode (Pattern Filter)
Configures the filter mode that defines how attribute values are matched against patterns.
| Mode | Filtering Condition |
|---|---|
| Substring | The attribute value contains the pattern as a substring |
| Full String | The attribute value equals the pattern |
| Regular Expression | The pattern as a regular expression matches the attribute value |
Case Sensitive
Configures the pattern filter to use case-sensitive substring or full string matching.
Amount Type
If Amount Type is Count, a Count number of data items with extremum values are kept. If Amount Type is Percentage, a Percentage percent of data items with extremum values are kept.
Amount
The number of data items to keep based on the Amount Type given.
Group By Column
If Group By Column is given, data items are first grouped based on their attribute values. Filtering is then applied on each group separately.
Distinct Values
If Distinct Values is set, count and percentage are calculated only based on distinct values.
For example, if Count is 1 for a maximum filter, all data items with the maximum value will be kept.