Levenshtein Distance
The string column comparisons are made using the Levenshtein distance (opens in a new tab) algorithm. Levenshtein distance is a string metric for measuring the difference between two sequences. Informally, the Levenshtein distance between two words is the minimum number of single-character edits (insertions, deletions or substitutions) required to change one word into the other.
For example, the Levenshtein distance between "kitten" and "sitting" is 3, since the following three edits change one into the other, and there is no way to do it with fewer than three edits.
- kitten → sitten (substitution of "s" for "k")
- sitten → sittin (substitution of "i" for "e")
- sittin → sitting (insertion of "g" at the end)
Consider the following tables:
| ID | Another ID | Yet Another ID | Name | Age |
|---|---|---|---|---|
| 1 | 101 | 201 | Jhn | 20 |
| 2 | 102 | 202 | Mry | 21 |
| 2 | 103 | 203 | Jne | 22 |
| 3 | 103 | 203 | Jck | 23 |
| 3 | 104 | 205 | Jll | 24 |
Expected Frame
| ID | Another ID | Yet Another ID | Name | Age |
|---|---|---|---|---|
| 1 | 101 | 201 | John | 28 |
| 2 | 102 | 202 | Mary | 31 |
| 2 | 103 | 203 | Jane | 32 |
| 3 | 103 | 203 | Jack | 33 |
| 3 | 104 | 205 | Jill | 34 |
You can immediately identify that the Name column in the Tested frame has one character missing at the 2nd index in each row. So the Levenshtein distance between Jhn and John is 1 and so on. The total sum of all the Levenshtein distances is 5. In the comparion report, the total of all the Levenshtein distances is reported. The comparison fails if the total is greater than zero.