SF patch #803449: modernize demo scripts
(Contributed by George Yoshida.)
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# A class which presents the reverse of a sequence without duplicating it.
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'''
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# From: "Steven D. Majewski" <sdm7g@elvis.med.virginia.edu>
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A class which presents the reverse of a sequence without duplicating it.
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From: "Steven D. Majewski" <sdm7g@elvis.med.virginia.edu>
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# It works on mutable or inmutable sequences.
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It works on mutable or inmutable sequences.
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#
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# >>> for c in Rev( 'Hello World!' ) : sys.stdout.write( c )
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>>> chars = list(Rev('Hello World!'))
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# ... else: sys.stdout.write( '\n' )
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>>> print ''.join(chars)
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# ...
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!dlroW olleH
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# !dlroW olleH
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#
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The .forw is so you can use anonymous sequences in __init__, and still
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# The .forw is so you can use anonymous sequences in __init__, and still
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keep a reference the forward sequence. )
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# keep a reference the forward sequence. )
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If you give it a non-anonymous mutable sequence, the reverse sequence
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# If you give it a non-anonymous mutable sequence, the reverse sequence
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will track the updated values. ( but not reassignment! - another
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# will track the updated values. ( but not reassignment! - another
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good reason to use anonymous values in creating the sequence to avoid
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# good reason to use anonymous values in creating the sequence to avoid
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confusion. Maybe it should be change to copy input sequence to break
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# confusion. Maybe it should be change to copy input sequence to break
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the connection completely ? )
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# the connection completely ? )
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#
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>>> nnn = range(3)
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# >>> nnn = range( 0, 3 )
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>>> rnn = Rev(nnn)
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# >>> rnn = Rev( nnn )
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>>> for n in rnn: print n
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# >>> for n in rnn: print n
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...
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# ...
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2
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# 2
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1
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# 1
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0
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# 0
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>>> for n in range(4, 6): nnn.append(n) # update nnn
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# >>> for n in range( 4, 6 ): nnn.append( n ) # update nnn
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...
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# ...
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>>> for n in rnn: print n # prints reversed updated values
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# >>> for n in rnn: print n # prints reversed updated values
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...
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# ...
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5
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# 5
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4
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# 4
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2
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# 2
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1
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# 1
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0
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# 0
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>>> nnn = nnn[1:-1]
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# >>> nnn = nnn[1:-1]
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>>> nnn
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# >>> nnn
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[1, 2, 4]
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# [1, 2, 4]
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>>> for n in rnn: print n # prints reversed values of old nnn
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# >>> for n in rnn: print n # prints reversed values of old nnn
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...
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# ...
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5
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# 5
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4
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# 4
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2
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# 2
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1
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# 1
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0
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# 0
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# >>>
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#
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#
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>>> WH = Rev('Hello World!')
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# WH = Rev( 'Hello World!' )
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>>> print WH.forw, WH.back
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# print WH.forw, WH.back
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Hello World! !dlroW olleH
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# nnn = Rev( range( 1, 10 ) )
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>>> nnn = Rev(range(1, 10))
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# print nnn.forw
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>>> print nnn.forw
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# print nnn
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[1, 2, 3, 4, 5, 6, 7, 8, 9]
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#
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>>> print nnn.back
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# produces output:
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[9, 8, 7, 6, 5, 4, 3, 2, 1]
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#
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# Hello World! !dlroW olleH
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>>> rrr = Rev(nnn)
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# [1, 2, 3, 4, 5, 6, 7, 8, 9]
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>>> rrr
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# [9, 8, 7, 6, 5, 4, 3, 2, 1]
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<1, 2, 3, 4, 5, 6, 7, 8, 9>
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#
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# >>>rrr = Rev( nnn )
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'''
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# >>>rrr
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# <1, 2, 3, 4, 5, 6, 7, 8, 9>
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from string import joinfields
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class Rev:
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class Rev:
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def __init__( self, seq ):
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def __init__(self, seq):
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self.forw = seq
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self.forw = seq
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self.back = self
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self.back = self
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def __len__( self ):
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return len( self.forw )
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def __len__(self):
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def __getitem__( self, j ):
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return len(self.forw)
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return self.forw[ -( j + 1 ) ]
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def __repr__( self ):
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def __getitem__(self, j):
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return self.forw[-(j + 1)]
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def __repr__(self):
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seq = self.forw
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seq = self.forw
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if type(seq) == type( [] ) :
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if isinstance(seq, list):
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wrap = '[]'
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wrap = '[]'
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sep = ', '
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sep = ', '
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elif type(seq) == type( () ) :
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elif isinstance(seq, tuple):
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wrap = '()'
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wrap = '()'
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sep = ', '
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sep = ', '
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elif type(seq) == type( '' ) :
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elif isinstance(seq, str):
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wrap = ''
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wrap = ''
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sep = ''
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sep = ''
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else:
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else:
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wrap = '<>'
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wrap = '<>'
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sep = ', '
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sep = ', '
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outstrs = []
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outstrs = [str(item) for item in self.back]
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for item in self.back :
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return wrap[:1] + sep.join(outstrs) + wrap[-1:]
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outstrs.append( str( item ) )
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return wrap[:1] + joinfields( outstrs, sep ) + wrap[-1:]
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def _test():
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import doctest, Rev
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return doctest.testmod(Rev)
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if __name__ == "__main__":
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_test()
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@ -2,27 +2,22 @@
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def vec(*v):
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def vec(*v):
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return apply(Vec, v)
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return Vec(*v)
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class Vec:
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class Vec:
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def __init__(self, *v):
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def __init__(self, *v):
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self.v = []
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self.v = list(v)
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for x in v:
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self.v.append(x)
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def fromlist(self, v):
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def fromlist(self, v):
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self.v = []
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if not isinstance(v, list):
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if type(v) <> type([]):
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raise TypeError
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raise TypeError
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self.v = v[:]
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self.v = v[:]
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return self
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return self
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def __repr__(self):
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def __repr__(self):
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return 'vec(' + `self.v`[1:-1] + ')'
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return 'vec(' + repr(self.v)[1:-1] + ')'
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def __len__(self):
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def __len__(self):
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return len(self.v)
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return len(self.v)
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@ -30,25 +25,19 @@ class Vec:
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def __getitem__(self, i):
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def __getitem__(self, i):
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return self.v[i]
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return self.v[i]
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def __add__(a, b):
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def __add__(self, other):
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# Element-wise addition
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# Element-wise addition
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v = []
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v = map(lambda x, y: x+y, self, other)
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for i in range(len(a)):
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v.append(a[i] + b[i])
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return Vec().fromlist(v)
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return Vec().fromlist(v)
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def __sub__(a, b):
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def __sub__(self, other):
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# Element-wise subtraction
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# Element-wise subtraction
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v = []
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v = map(lambda x, y: x-y, self, other)
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for i in range(len(a)):
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v.append(a[i] - b[i])
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return Vec().fromlist(v)
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return Vec().fromlist(v)
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def __mul__(self, scalar):
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def __mul__(self, scalar):
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# Multiply by scalar
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# Multiply by scalar
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v = []
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v = map(lambda x: x*scalar, self.v)
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for i in range(len(self.v)):
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v.append(self.v[i]*scalar)
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return Vec().fromlist(v)
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return Vec().fromlist(v)
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@ -59,6 +48,7 @@ def test():
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print a
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print a
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print b
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print b
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print a+b
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print a+b
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print a-b
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print a*3.0
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print a*3.0
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test()
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test()
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