Python,strings
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<![CDATA[
>>> line = 'aaa bbb ccc'
>>> col1 = line[0:3]
>>> col3 = line[8:]
>>> col1
'aaa'
>>> col3
'ccc'
>>> line = 'aaa bbb ccc'
>>> cols = line.split()
>>> cols
['aaa', 'bbb', 'ccc']
>>> line = 'bob,hacker,40'
>>> line.split(',')
['bob', 'hacker', '40']
>>> line = "i'mSPAMaSPAMlumberjack"
>>> line.split("SPAM")
["i'm", 'a', 'lumberjack']
>>> S = 'a+b+c+'
>>> X = S.replace('+','spam')
>>> x
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 'x' is not defined
>>> X
'aspambspamcspam'
>>> import string
>>> y = string.replace(S,'+','spam')
>>> y
'aspambspamcspam'
>>>
>>> S = 'spammy'
>>> S = S[:3] + 'xx' + S[5:]
>>> S
'spaxxy'
>>> S = 'spammy'
>>> S = S.replace('mm','xx')
>>> S
'spaxxy'
>>> 'aa$bb$cc$dd'.replace('$','SPAM')
'aaSPAMbbSPAMccSPAMdd'
>>> S = 'xxxxSPAMxxxxSPAMxxxx'
>>> where = S.find('SPAM')
>>> where
4
>>> S = S[:where] + 'EGGS' + S[(where+4):]
>>> S
'xxxxEGGSxxxxSPAMxxxx'
>>> S = 'xxxxSPAMxxxxSPAMxxxx'
>>> S.replace('SPAM', 'EGGS')
'xxxxEGGSxxxxEGGSxxxx'
>>> S
'xxxxSPAMxxxxSPAMxxxx'
>>> S.replace('SPAM', 'EGGS', 1)
'xxxxEGGSxxxxSPAMxxxx'
>>> S = 'spammy'
>>> L = list(S)
>>> L
['s', 'p', 'a', 'm', 'm', 'y']
>>> L[3] = 'x'
>>> L[4] = 'x'
>>> L
['s', 'p', 'a', 'x', 'x', 'y']
>>> S = ''.join(L)
>>> S
'spaxxy'
>>> 'SPAM'.join(['eggs','sausage','ham','toast'])
'eggsSPAMsausageSPAMhamSPAMtoast'
>>>
>>> exclamation = "Ni"
>>> "The knights who say %s!" % exclamation
'The knights who say Ni!'
>>> "%d %s %d you" % (1,'spam',4)
'1 spam 4 you'
>>> "%s -- %s -- %s" % (42, 3.14159, [1,2,3])
'42 -- 3.14159 -- [1, 2, 3]'
>>> x = 1234
>>> res = "integers: ...%d...%-6d...%06d" % (x,x,x)
>>> res
'integers: ...1234...1234 ...001234'
>>> x = 1.23456789
>>> x
1.2345678899999999
>>> '%e | %f | %g' % (x,x,x)
'1.234568e+000 | 1.234568 | 1.23457'
>>> '%-6.2f | %05.2f | %+06.1f' % (x,x,x)
'1.23 | 01.23 | +001.2'
>>> "%s" % x,str(x)
('1.23456789', '1.23456789')
>>> "%(n)d %(x)s" % {"n":1, "x":"spam"}
'1 spam'
>>> food = 'spam'
>>> age = 40
>>> vars()
{'exclamation': 'Ni', '__builtins__': <module '__builtin__' (built-in)>, 'res':
'integers: ...1234...1234 ...001234', 'age': 40, 'food': 'spam', 'x': 1.2345678
899999999, '__name__': '__main__', '__doc__': None}
>>> "%(age)d %(food)s" % vars()
'40 spam'
>>>
Indexing and Slicing
>>> S = 'spam'
>>> S[0], S[-2]
('s', 'a')
>>> S[1:3], S[1:], S[:-1]
('pa', 'pam', 'spa')
>>> "ys" + 1
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: cannot concatenate 'str' and 'int' objects
>>> int("42"), str(42)
(42, '42')
>>> string.atoi("42"),'42'
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 'string' is not defined
>>> string.atoi("42"),`42`
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 'string' is not defined
>>> int("42") + 1
43
>>> "spam" + str(42)
'spam42'
>>> str(3.1415), float("1.5")
('3.1415', 1.5)
>>> text = "1.234E-10"
>>> float(text)
1.2340000000000001e-010
>>> S
'spam'
>>> S[0] = "x"
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: object doesn't support item assignment
>>> S = S + 'SPAM!'
>>> S
'spamSPAM!'
>>> S = S[:4] + 'Burger' + S[-1]
>>> S
'spamBurger!'
>>> 'That is %d %s bird!' % (1, 'dead')
'That is 1 dead bird!'
>>>
>>> len('abc')
3
>>> 'abc' + 'def'
'abcdef'
>>> 'Ni!' * 4
'Ni!Ni!Ni!Ni!'
>>> print '------...more...---'
------...more...---
>>> print '_'*80
________________________________________________________________________________
>>> print '------ ...more... ---'
------ ...more... ---
>>> print '-'*80
--------------------------------------------------------------------------------
>>> myjob = "hacker"
>>> for c in myjob: print c,
...
h a c k e r
>>> "k" in myjob
True
>>> "z" in myjob
False
>>>
>>> path = r'C:\new\text.dat'
>>> path
'C:\\new\\text.dat'
>>> print path
C:\new\text.dat
>>> len(path)
15
>>>
Triple quotes code multiline block strings
>>> mantra = """Always look
... on the bright
... side of life."""
>>> mantra
'Always look\non the bright\nside of life.'
>>>
>>> u'spam'
u'spam'
>>> 'ni' + u'spam'
u'nispam'
>>> str(u'spam')
'spam'
>>> unicode('spam')
u'spam'
>>> u'ab\x20cd'
u'ab cd'
>>> u'ab\u0020cd'
u'ab cd'
>>> u'ab\U00000020cd'
u'ab cd'
Python 2.3.5 (#62, Feb 8 2005, 16:23:02) [MSC v.1200 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> 'shrubbery',"shrubbery"
('shrubbery', 'shrubbery')
>>> 'knight"s',"knight's"
('knight"s', "knight's")
>>> title = "Meaning " 'of' " Life"
>>> title
'Meaning of Life'
>>> 'knight\'s',"knight\""
("knight's", 'knight"')
>>> 'knight\'s',"knight\"s"
("knight's", 'knight"s')
>>> s = 'a\nb\tc'
>>> print s
a
b c
>>> len(s)
5
>>> s = 'a\0b\0c'
>>> s
'a\x00b\x00c'
>>> len(s)
5
>>> s = '\001\002\x03'
>>> s
'\x01\x02\x03'
>>> len(s)
3
>>> x = "C:\py\code"
>>> x
'C:\\py\\code'
>>> len(x)
10
>>>
c:\python>python
Python 2.3.5 (#62, Feb 8 2005, 16:23:02) [MSC v.1200 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> s1 = ''
>>> print s1
>>> s2 = "span's"
>>> print s2
span's
>>> s3 = r'\temp\spam'
>>> print s3
\temp\spam
>>> s4 = u'spam'
>>> print s4
spam
>>> s4 = u'人'
>>> print s4
?l
>>> myfile = open('myfile','w')
>>> myfile.write('s4\n')
>>> myfile.close()
>>> myfile = open('myfile1.txt','w')
>>> myfile.write(s4)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
UnicodeEncodeError: 'ascii' codec can't encode character u'\x90' in position 0:
ordinal not in range(128)
>>>
]]>
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