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This article mainly introduces examples of the python difflib module in detail, which has certain reference value. Interested friends can refer to the classes and methods provided by the
difflib module for sequencing. Differential comparison, it can compare files and generate differential result text or differential comparison page in html format. If you need to compare directories, you can use the filecmp module.
class difflib.SequenceMatcher
This class provides methods for comparing sequence pairs of arbitrary hashable types. This method will find the largest consecutive matching sequence that does not contain 'garbage' elements.
By comparing the complexity of the algorithm, it has n square operations in the worst case due to the original Gestalt matching algorithm, and has linear efficiency in the best case.
It has automatic garbage heuristics that can treat characters that are repeated more than 1% of the fragment or repeated 200 times as garbage. This feature can be turned off by setting autojunk to false.
class difflib.Differ
This class compares the differences between text lines and produces difference results or incremental results suitable for human reading. Each of the results The representation of the parts is as follows:
##class difflib.HtmlDiff
This class can be used to create HTML tables (or contain tables html file), corresponding display on both sides or row-by-row display to compare the difference results. make_file(fromlines, tolines [, fromdesc][, todesc][, context][, numlines])make_table(fromlines, tolines [, fromdesc][, todesc][, context ][, numlines])difflib.context_diff(a, b[, fromfile][, tofile][, fromfiledate][, tofiledate][, n][, lineterm])
Generator that compares a and b (a list of strings) and returns a line of difference textExample:
>>> s1 = ['bacon\n', 'eggs\n', 'ham\n', 'guido\n'] >>> s2 = ['python\n', 'eggy\n', 'hamster\n', 'guido\n'] >>> for line in context_diff(s1, s2, fromfile='before.py', tofile='after.py'): ... sys.stdout.write(line) *** before.py --- after.py *************** *** 1,4 **** ! bacon ! eggs ! ham guido --- 1,4 ---- ! python ! eggy ! hamster guido
difflib.get_close_matches(word, possibilities [, n][, cutoff])
Return the list of maximum matching results>>> get_close_matches('appel', ['ape', 'apple', 'peach', 'puppy']) ['apple', 'ape'] >>> import keyword >>> get_close_matches('wheel', keyword.kwlist) ['while'] >>> get_close_matches('apple', keyword.kwlist) [] >>> get_close_matches('accept', keyword.kwlist) ['except']
difflib.ndiff(a, b[, linejunk][, charjunk])
Compare a and b (string list) and return a Differ-style difference result Example:
>>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1), ... 'ore\ntree\nemu\n'.splitlines(1)) >>> print ''.join(diff), - one ? ^ + ore ? ^ - two - three ? - + tree + emu
difflib.restore(sequence, which)
Returns a result produced by two aligned sequences>>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1), ... 'ore\ntree\nemu\n'.splitlines(1)) >>> diff = list(diff) # materialize the generated delta into a list >>> print ''.join(restore(diff, 1)), one two three >>> print ''.join(restore(diff, 2)), ore tree emu
difflib.unified_diff(a, b[, fromfile][, tofile][, fromfiledate][, tofiledate ][, n][, lineterm])
Compare a and b (string list) and return a difference result in unified diff format.>>> s1 = ['bacon\n', 'eggs\n', 'ham\n', 'guido\n'] >>> s2 = ['python\n', 'eggy\n', 'hamster\n', 'guido\n'] >>> for line in unified_diff(s1, s2, fromfile='before.py', tofile='after.py'): ... sys.stdout.write(line) --- before.py +++ after.py @@ -1,4 +1,4 @@ -bacon -eggs -ham +python +eggy +hamster guidoPractical application exampleCompare two files and then generate an HTML file showing the difference results
#coding:utf-8 ''' file:difflibeg.py date:2017/9/9 10:33 author:lockey email:lockey@123.com desc:diffle module learning and practising ''' import difflib hd = difflib.HtmlDiff() loads = '' with open('G:/python/note/day09/0907code/hostinfo/cpu.py','r') as load: loads = load.readlines() load.close() mems = '' with open('G:/python/note/day09/0907code/hostinfo/mem.py', 'r') as mem: mems = mem.readlines() mem.close() with open('htmlout.html','a+') as fo: fo.write(hd.make_file(loads,mems)) fo.close()Running results:
## Generated html file comparison results:
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