9.2.6 Keying Difference Comparison 'FieldComparatorKeyDiff'

9.2.6 Keying Difference Comparison '`FieldComparatorKeyDiff`'

This field comparator compares the two fields (or field lists) given to it as strings character-wise, with a maximum number of different characters that can be tolerated. This number has to be set with the argument max_key_diff. If the number of different characters is larger than zero but equal to or smaller than max_key_diff the partial agreement weight is calculated using the following formula.

$\begin{eqnarray*} partial\_agreement & = & agree\_weight - \left( \frac{num\_key... ...f+1} \right) * \\ ~& ~& (agree\_weight + abs(disagree\_weight)) \end{eqnarray*}$

If the number of key differences is larger than max_key_diff then the disagreement weight is returned.

This field comparator can also be used to compare numerical fields, such as date of birth, telephone numbers, etc.

If a frequency table is given for this field comparator, both agreement and disagreement weights will be calculated using the frequencies of the value in the input fields that are compared, as described in Section 9.2.1.