reverse a string in Python
How to reverse a string?
Simple! :-)
s = 'abc'
s = s[::-1]
print s
Simple! :-)
Strip HTML tags using Python
We often need to strip HTML tags from string (or HTML source). I usually do it using a simple regular expression in Python. Here is my function to strip HTML tags: def remove_html_tags(data): p = re.compile(r'<.*?>') return p.sub('', data) Here is another function to remove more than one consecutive white spaces: def remove_extra_spaces(data): p = re.compile(r'\s+') return p.sub(' ', data) Note that re module needs to be imported in order to use regular expression. Here you can find an updated code that gets the text from html: http://love-python.blogspot.com/2011/04/html-to-text-in-python.html
Comments
--Hans
it really helpful.
thanks.
or any link for explanation will be helpful.
thanks.
Example:
>>> foo = [2, 5, 1, 8]
Regular slice (returns all)
>>> foo[:]
[2, 5, 1, 8]
Slice with stride (returns every nth)
>>> foo[::2]
[2, 1]
Stride works inversely as well
>>> foo[::-2]
[8, 5]
Hence it can be used to reverse a string (stride backwards using step length of one)
>>> 'foobar'[::-1]
'raboof'
There is another way to reverse as well. This can be done using "reversed" generator:
>>> ''.join([char for char in reversed('foobar')])
'raboof'
As the list comprehension returns a list I had to join it separately. Normally the [::-1] trick should work just fine. "reversed" may be useful in some special cases, however.
Check out http://www.python.org/doc/2.3.5/whatsnew/section-slices.html for more comprehensive documentation.
s = s[::2]
print s
#for this code it returns ac
#how
Does anyone know what i should use to extract string/substring from a string?
print $string = reverse("ABC")
>>>print s[:]
spam
>>>print s[::-1]
maps
>>>print s[0:len(s)]
spam
>>>print s[0:len(s):-1]
(prints nothing)
Any reason, why ??
s='abc'
print s[::-2]
returns 'ca' only...
You could do this:
oct(12)
that would return
'014' as a string
To enter an octal number literal, precede with a 0:
0122 will return 82 in base 10
to go from an octal string to an int:
int('014',8)
>>> sentence = "one two three four"
>>> ' '.join( [ word[::-1] for word in sentence.split() ] )[::-1]
'four three two one'
>>> sentence = "one two three four"
>>> ' '.join( [ word for word in sentence.split() ] [::-1])
'four three two one'
[::-1]
[:] <-- this gets all of the string
while [::(value)] skips or reverse the string. if it is negative, the skipping starts from the last character of the string depends on the number.
for example, you can put -2 instead of -1.
s = 'abcdef'
s = s[::-2]
print s
if counted base on the slice number, it would creat a group of three which are fe, dc and ba. the first character of each group (f,d,b) will appended to formed a value and stored it to the variable 's'.
revword = ''
for letter in reversed(word): revword += letter
print revword
Full code solutions with test data and output, described in clear English and tested on the same page
print (" ".join(str.split()[::-1])) would work for reversing string word by word :)
Thought to share it . :)