s = 'abc'
s = s[::-1]
print s
Simple! :-)
programming faq
3 months ago
Sunday, February 10, 2008
Subscribe to:
Post Comments (Atom)
Popular Posts
-
A common problem beginners face is to remove duplicate items from a list. In Python it can be done easily. First make a set from the list an...
-
Python has a very simple way to convert text to ASCII and ASCII to text. To find the ASCII value of a character use the ord() function. Exa...
-
How to reverse a string? s = 'abc' s = s[::-1] print s Simple! :-)
-
Today I needed to write a Python code for 'Press any key to continue' feature. First I wrote the code: raw_input("Press Any Key...
-
I know though some of you are already using Python for some time, you still get confused when you hear the term generator and yield. Let me...
-
It's a very well known problem given to the beginners, 'swap values of two variables'. In our first introductory programming cou...
-
I have been using Python to write web crawler/spider/scraper for a long time. And it's an interesting experience indeed. The good news i...
-
Python has useful module named csv to deal with csv files. But recently I faced a problem reading csv files and want to share with you how ...
-
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 funct...
-
For last few days, I am doing an interesting project, for which I require to execute some Linux commands from Python. So I searched a bit fo...
Pages
My Favorite Blogs
-
-
Calling C functions from Python5 months ago
-
The party's over11 months ago
-
testing javascript1 year ago
Meet the Followers
Categories
- add (1)
- ASCII Code (1)
- background process (1)
- backtracking (2)
- basic http authentication (1)
- Beautiful Soup (1)
- code search (1)
- concatenate (1)
- cookie (1)
- crawler (1)
- csv read (1)
- CSV write in Python (3)
- design pattern (1)
- dictionary (1)
- django (1)
- eclipse (1)
- email address scraper (1)
- execute (1)
- extract domain (1)
- facebook (1)
- facebook application (1)
- fast python I/O (1)
- floating point number (1)
- ftp upload (1)
- generator (1)
- get remote file size (http) (1)
- getacoder (1)
- getch (1)
- google app engine. (1)
- HTML (1)
- HTTP POST (1)
- HTTP Response Header (1)
- infix (1)
- json (1)
- lambda function (1)
- Leap Year (1)
- linux (1)
- linux command (1)
- list (1)
- list comprehension (1)
- login script in python (1)
- lxml (1)
- machine learning (1)
- mongodb (1)
- nohup (1)
- nosql (1)
- online course (1)
- online judge (1)
- OOP in Python (1)
- Palindrome (1)
- permutation (1)
- Plain Text (1)
- postfix (1)
- prime number (2)
- programming contest (1)
- proxy (3)
- pyhp (1)
- PyS60 (3)
- python (20)
- Python 2.5.2 (1)
- python book (1)
- python code (1)
- python command line argument (1)
- python console input (1)
- Python Course (1)
- Python create thumbnail (1)
- Python Database Programming (2)
- python dictionary (1)
- python download file (1)
- python ebook (1)
- python file (1)
- Python for Mobile Phone (6)
- Python Free eBook (1)
- python freelance work (3)
- python hex to ASCII (1)
- python http get (1)
- python http post (1)
- python hypertext preprocessor (1)
- Python IDE (2)
- Python Image resize (1)
- python iterator (1)
- Python Jobs (2)
- python list (2)
- Python List Comprehension (1)
- python list copy (2)
- python localtime (1)
- python mysqldb (2)
- python programming course (1)
- Python reformat string data (1)
- Python send email (1)
- python unicode (2)
- python urlparse (1)
- python version (1)
- Python video (1)
- python web crawler (7)
- python web frameworks (1)
- python web spider (7)
- random elements (1)
- random string (1)
- random word (1)
- read firefox cache (1)
- recommendation engine (1)
- recursion (2)
- reduce image size (1)
- regular expression (3)
- remove duplicate (1)
- rentacoder (1)
- requests (2)
- reusable python script (1)
- reverse polish notation (1)
- round (1)
- scraper (1)
- set (1)
- set comprehension (1)
- settimeout (1)
- stand alone python script (1)
- sub-set (1)
- subset (1)
- swap integers (1)
- swap values python (1)
- twitter (1)
- twitter api (2)
- twitter search (1)
- typeerror (1)
- unix (1)
- update (1)
- url redirect (1)
- urllib2 (1)
- user agent (1)
- user-agent (1)
- web crawler (5)
- web spider (4)
- write large file (1)
- xml (1)
- xml parsing (1)
- yield (1)
Explore Python
Site Statistics
Subscribe To Love-Python
Posts
Comments
Search This Blog
26 comments:
Yeah, but it might be useful to explain to newbies what the slice notation does. If I were new to Python, then "s[::-1]" would look positively odd to me... I certainly would not think it reverses the string. Just a thought. :-)
--Hans
Thanks for your comment. I didn't explain it as I thought it would be fun for anyone who tries to think how s[::-1] works :)
i appreciate.
it really helpful.
thanks.
Simple yet so useful! Thanks :)
explain how it works ?
or any link for explanation will be helpful.
thanks.
Bhavin Patel: "::" is known as stride notation.
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.
Thank you very much its simple and nice
It's very nice... yare
s = 'abc'
s = s[::2]
print s
#for this code it returns ac
#how
it should be "ca", isn't it?
thanks it is very helpful and explained very well
Does anyone know what i should use to extract string/substring from a string?
That really proves the power of python, for which it would take couple of lines in other languages.
Python is really a nice language. Just for comparison, that is how i would do it in perl:
print $string = reverse("ABC")
thanks......workz perfectly as i expected
Awesome thing!!
>>>s='spam'
>>>print s[:]
spam
>>>print s[::-1]
maps
>>>print s[0:len(s)]
spam
>>>print s[0:len(s):-1]
(prints nothing)
Any reason, why ??
@saikat
s='abc'
print s[::-2]
returns 'ca' only...
i'm new to python, i need a program to convert any decimal number in to octal(base 8):using python 2.7 ,can any one give me an idea how to write it :please help me~!
@casper
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)
You can also use this technique to reverse words in a sentence:
>>> sentence = "one two three four"
>>> ' '.join( [ word[::-1] for word in sentence.split() ] )[::-1]
'four three two one'
The above example is simplified as
>>> sentence = "one two three four"
>>> ' '.join( [ word for word in sentence.split() ] [::-1])
'four three two one'
but when I tried it, it doesn't print the space between the reversed i.e the output is like this fourthreetwoone
Hmm, i did it but here's what I thought regarding this.
[::-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'.
maybe the easiest way is
revword = ''
for letter in reversed(word): revword += letter
print revword
Post a Comment