Thursday 16 December 2010
teethgrinder :: python spider using mechanize pullparser and beautiful soup
python spider using mechanize pullparser and beautiful soup
Tuesday 7 December 2010
http://svn.python.org/projects/python/trunk/Demo/pdist/rcslib.py
"""RCS interface module.Defines the class RCS, which represents a directory with rcs versionfiles and (possibly) corresponding work files."""import fnmatchimport osimport reimport stringimport tempfileclass RCS: """RCS interface class (local filesystem version). An instance of this class represents a directory with rcs version files and (possible) corresponding work files. Methods provide access to most rcs operations such as checkin/checkout, access to the rcs metadata (revisions, logs, branches etc.) as well as some filesystem operations such as listing all rcs version files. XXX BUGS / PROBLEMS - The instance always represents the current directory so it's not very useful to have more than one instance around simultaneously """ # Characters allowed in work file names okchars = string.ascii_letters + string.digits + '-_=+' def __init__(self): """Constructor.""" pass def __del__(self): """Destructor.""" pass # --- Informational methods about a single file/revision --- def log(self, name_rev, otherflags = ''): """Return the full log text for NAME_REV as a string. Optional OTHERFLAGS are passed to rlog. """ f = self._open(name_rev, 'rlog ' + otherflags) data = f.read() status = self._closepipe(f) if status: data = data + "%s: %s" % status elif data[-1] == '\n': data = data[:-1] return data def head(self, name_rev): """Return the head revision for NAME_REV""" dict = self.info(name_rev) return dict['head'] def info(self, name_rev): """Return a dictionary of info (from rlog -h) for NAME_REV The dictionary's keys are the keywords that rlog prints (e.g. 'head' and its values are the corresponding data (e.g. '1.3'). XXX symbolic names and locks are not returned """ f = self._open(name_rev, 'rlog -h') dict = {} while 1: line = f.readline() if not line: break if line[0] == '\t': # XXX could be a lock or symbolic name # Anything else? continue i = string.find(line, ':') if i > 0: key, value = line[:i], string.strip(line[i+1:]) dict[key] = value status = self._closepipe(f) if status: raise IOError, status return dict # --- Methods that change files --- def lock(self, name_rev): """Set an rcs lock on NAME_REV.""" name, rev = self.checkfile(name_rev) cmd = "rcs -l%s %s" % (rev, name) return self._system(cmd) def unlock(self, name_rev): """Clear an rcs lock on NAME_REV.""" name, rev = self.checkfile(name_rev) cmd = "rcs -u%s %s" % (rev, name) return self._system(cmd) def checkout(self, name_rev, withlock=0, otherflags=""): """Check out NAME_REV to its work file. If optional WITHLOCK is set, check out locked, else unlocked. The optional OTHERFLAGS is passed to co without interpretation. Any output from co goes to directly to stdout. """ name, rev = self.checkfile(name_rev) if withlock: lockflag = "-l" else: lockflag = "-u" cmd = 'co %s%s %s %s' % (lockflag, rev, otherflags, name) return self._system(cmd) def checkin(self, name_rev, message=None, otherflags=""): """Check in NAME_REV from its work file. The optional MESSAGE argument becomes the checkin message (default "<none>" if None); or the file description if this is a new file. The optional OTHERFLAGS argument is passed to ci without interpretation. Any output from ci goes to directly to stdout. """ name, rev = self._unmangle(name_rev) new = not self.isvalid(name) if not message: message = "<none>" if message and message[-1] != '\n': message = message + '\n' lockflag = "-u" if new: f = tempfile.NamedTemporaryFile() f.write(message) f.flush() cmd = 'ci %s%s -t%s %s %s' % \ (lockflag, rev, f.name, otherflags, name) else: message = re.sub(r'([\"$`])', r'\\\1', message) cmd = 'ci %s%s -m"%s" %s %s' % \ (lockflag, rev, message, otherflags, name) return self._system(cmd) # --- Exported support methods --- def listfiles(self, pat = None): """Return a list of all version files matching optional PATTERN.""" files = os.listdir(os.curdir) files = filter(self._isrcs, files) if os.path.isdir('RCS'): files2 = os.listdir('RCS') files2 = filter(self._isrcs, files2) files = files + files2 files = map(self.realname, files) return self._filter(files, pat) def isvalid(self, name): """Test whether NAME has a version file associated.""" namev = self.rcsname(name) return (os.path.isfile(namev) or os.path.isfile(os.path.join('RCS', namev))) def rcsname(self, name): """Return the pathname of the version file for NAME. The argument can be a work file name or a version file name. If the version file does not exist, the name of the version file that would be created by "ci" is returned. """ if self._isrcs(name): namev = name else: namev = name + ',v' if os.path.isfile(namev): return namev namev = os.path.join('RCS', os.path.basename(namev)) if os.path.isfile(namev): return namev if os.path.isdir('RCS'): return os.path.join('RCS', namev) else: return namev def realname(self, namev): """Return the pathname of the work file for NAME. The argument can be a work file name or a version file name. If the work file does not exist, the name of the work file that would be created by "co" is returned. """ if self._isrcs(namev): name = namev[:-2] else: name = namev if os.path.isfile(name): return name name = os.path.basename(name) return name def islocked(self, name_rev): """Test whether FILE (which must have a version file) is locked. XXX This does not tell you which revision number is locked and ignores any revision you may pass in (by virtue of using rlog -L -R). """ f = self._open(name_rev, 'rlog -L -R') line = f.readline() status = self._closepipe(f) if status: raise IOError, status if not line: return None if line[-1] == '\n': line = line[:-1] return self.realname(name_rev) == self.realname(line) def checkfile(self, name_rev): """Normalize NAME_REV into a (NAME, REV) tuple. Raise an exception if there is no corresponding version file. """ name, rev = self._unmangle(name_rev) if not self.isvalid(name): raise os.error, 'not an rcs file %r' % (name,) return name, rev # --- Internal methods --- def _open(self, name_rev, cmd = 'co -p', rflag = '-r'): """INTERNAL: open a read pipe to NAME_REV using optional COMMAND. Optional FLAG is used to indicate the revision (default -r). Default COMMAND is "co -p". Return a file object connected by a pipe to the command's output. """ name, rev = self.checkfile(name_rev) namev = self.rcsname(name) if rev: cmd = cmd + ' ' + rflag + rev return os.popen("%s %r" % (cmd, namev)) def _unmangle(self, name_rev): """INTERNAL: Normalize NAME_REV argument to (NAME, REV) tuple. Raise an exception if NAME contains invalid characters. A NAME_REV argument is either NAME string (implying REV='') or a tuple of the form (NAME, REV). """ if type(name_rev) == type(''): name_rev = name, rev = name_rev, '' else: name, rev = name_rev for c in rev: if c not in self.okchars: raise ValueError, "bad char in rev" return name_rev def _closepipe(self, f): """INTERNAL: Close PIPE and print its exit status if nonzero.""" sts = f.close() if not sts: return None detail, reason = divmod(sts, 256) if reason == 0: return 'exit', detail # Exit status signal = reason&0x7F if signal == 0x7F: code = 'stopped' signal = detail else: code = 'killed' if reason&0x80: code = code + '(coredump)' return code, signal def _system(self, cmd): """INTERNAL: run COMMAND in a subshell. Standard input for the command is taken from /dev/null. Raise IOError when the exit status is not zero. Return whatever the calling method should return; normally None. A derived class may override this method and redefine it to capture stdout/stderr of the command and return it. """ cmd = cmd + " </dev/null" sts = os.system(cmd) if sts: raise IOError, "command exit status %d" % sts def _filter(self, files, pat = None): """INTERNAL: Return a sorted copy of the given list of FILES. If a second PATTERN argument is given, only files matching it are kept. No check for valid filenames is made. """ if pat: def keep(name, pat = pat): return fnmatch.fnmatch(name, pat) files = filter(keep, files) else: files = files[:] files.sort() return files def _remove(self, fn): """INTERNAL: remove FILE without complaints.""" try: os.unlink(fn) except os.error: pass def _isrcs(self, name): """INTERNAL: Test whether NAME ends in ',v'.""" return name[-2:] == ',v'via ScribeFire
Wednesday 1 December 2010
BBP formula in Python
See http://mathworld.wolfram.com/BBPFormula.html
Not the most efficient Python but it works.
def x(n):
return (4.0/(8*n+1)-2.0/(8*n+4) - 1.0/(8*n+5) -1.0/(8*n+6))*((1.0/16)**n)
s = 0
for i in range(n):
s+=x(i)
return s
>>> pi(1)
3.1333333333333333
>>> pi(2)
3.1414224664224664
>>> pi(4)
3.1415924575674357
>>> pi(10)
3.1415926535897913
>>> pi(20)
3.141592653589793
>>> pi(40)
3.141592653589793
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