Construct a SequenceMatcher. Optional arg isjunk is None (the default), or a one-argument function that takes a sequence element and returns true iff the element is junk. None is equivalent to passing "lambda x: 0", i.e. no elements are considered to be junk.
(self, isjunk=None, a='', b='', autojunk=True)
| 118 | """ |
| 119 | |
| 120 | def __init__(self, isjunk=None, a='', b='', autojunk=True): |
| 121 | """Construct a SequenceMatcher. |
| 122 | |
| 123 | Optional arg isjunk is None (the default), or a one-argument |
| 124 | function that takes a sequence element and returns true iff the |
| 125 | element is junk. None is equivalent to passing "lambda x: 0", i.e. |
| 126 | no elements are considered to be junk. For example, pass |
| 127 | lambda x: x in " \\t" |
| 128 | if you're comparing lines as sequences of characters, and don't |
| 129 | want to synch up on blanks or hard tabs. |
| 130 | |
| 131 | Optional arg a is the first of two sequences to be compared. By |
| 132 | default, an empty string. The elements of a must be hashable. See |
| 133 | also .set_seqs() and .set_seq1(). |
| 134 | |
| 135 | Optional arg b is the second of two sequences to be compared. By |
| 136 | default, an empty string. The elements of b must be hashable. See |
| 137 | also .set_seqs() and .set_seq2(). |
| 138 | |
| 139 | Optional arg autojunk should be set to False to disable the |
| 140 | "automatic junk heuristic" that treats popular elements as junk |
| 141 | (see module documentation for more information). |
| 142 | """ |
| 143 | |
| 144 | # Members: |
| 145 | # a |
| 146 | # first sequence |
| 147 | # b |
| 148 | # second sequence; differences are computed as "what do |
| 149 | # we need to do to 'a' to change it into 'b'?" |
| 150 | # b2j |
| 151 | # for x in b, b2j[x] is a list of the indices (into b) |
| 152 | # at which x appears; junk and popular elements do not appear |
| 153 | # fullbcount |
| 154 | # for x in b, fullbcount[x] == the number of times x |
| 155 | # appears in b; only materialized if really needed (used |
| 156 | # only for computing quick_ratio()) |
| 157 | # matching_blocks |
| 158 | # a list of (i, j, k) triples, where a[i:i+k] == b[j:j+k]; |
| 159 | # ascending & non-overlapping in i and in j; terminated by |
| 160 | # a dummy (len(a), len(b), 0) sentinel |
| 161 | # opcodes |
| 162 | # a list of (tag, i1, i2, j1, j2) tuples, where tag is |
| 163 | # one of |
| 164 | # 'replace' a[i1:i2] should be replaced by b[j1:j2] |
| 165 | # 'delete' a[i1:i2] should be deleted |
| 166 | # 'insert' b[j1:j2] should be inserted |
| 167 | # 'equal' a[i1:i2] == b[j1:j2] |
| 168 | # isjunk |
| 169 | # a user-supplied function taking a sequence element and |
| 170 | # returning true iff the element is "junk" -- this has |
| 171 | # subtle but helpful effects on the algorithm, which I'll |
| 172 | # get around to writing up someday <0.9 wink>. |
| 173 | # DON'T USE! Only __chain_b uses this. Use "in self.bjunk". |
| 174 | # bjunk |
| 175 | # the items in b for which isjunk is True. |
| 176 | # bpopular |
| 177 | # nonjunk items in b treated as junk by the heuristic (if used). |