need to write a simple web crawler

Its quite easy actually, you need one thing, one way to parse a html page (which is found in the python lib), and as you pointed out in your post, Breath first search (BFS) and depth first search (DFS). You also need some kind of structure to determine if you visited a certain page before (maybe a hash list?)

Lets assume that we use BFS, and use pythons list method, and that you start on a certain page (www.thescripts.com ?:)

hash = {}
stack = []
stack.push("www.thescripts.com")

while(len(stack) > 0):
currpage = stack.pop()
hash[currpage] = 1 # sets it to visited
links = findlinks(currpage) # this method finds all the links of the page
# here you can do what you would do, like finding some text, downloading
# some image etc etc
# push all the links on the stack


This was strictly psuedo code, since I haven't got a python interpreter here. If you still need it, I could write you a simple crawler.

-kudos

Quote: Originally Posted by Pradeep Vasudevan hai i am a student and need to write a simple web crawler using python and need some guidance of how to start.. i need to crawl web pages using BFS and also DFS... one using stacks and other using queues... i will try on the obsolete web pages only and so tht i can learn of how to do that.. i have taken a course called search engines and need some help in doing that... help in any knind would be appreciated.. thank u

Hi friend.. me too involving develpin a crawler.. share the deas you got please........

Quote: Originally Posted by squzer Hi friend.. me too involving develpin a crawler.. share the deas you got please........

Hi, what do you want to get from your crawl?

-kudos

I am looking for one that will read from a list of urls and crawl them for certain text words and then list the results.

I am also trying for that but my crawler takes a hell a lot of time to crwal i have done it in python. Can you folks give me some clue

I have done crawler also which parses URLs from html. I think that python's html parser modules only work with clean & valid html code... and net is full of dirty html! so get ready to write your own html parser =)

Quote: Originally Posted by kudos Its quite easy actually, you need one thing, one way to parse a html page (which is found in the python lib), and as you pointed out in your post, Breath first search (BFS) and depth first search (DFS). You also need some kind of structure to determine if you visited a certain page before (maybe a hash list?) Lets assume that we use BFS, and use pythons list method, and that you start on a certain page (www.thescripts.com ?:) hash = {} stack = [] stack.push("www.thescripts.com") while(len(stack) > 0): currpage = stack.pop() hash[currpage] = 1 # sets it to visited links = findlinks(currpage) # this method finds all the links of the page # here you can do what you would do, like finding some text, downloading # some image etc etc # push all the links on the stack Code: ( text ) for l in links:   if(hash[l] != 1):    stack.push(l) This was strictly psuedo code, since I haven't got a python interpreter here. If you still need it, I could write you a simple crawler. -kudos

I'm very interested how web crawler works..Would you mind if I ask for a sample code so that i could study and later make my own?

hi, i am trying to make a crawler and have the most frequency keywords of the pages of one site ... any idea??

Hi, I need to write a simple crawler too. it must have the ability to capture webpages from a certain site for example ww.CNN.com

and also it must parse those HTML webpages. I need any sample code please..urgently in order to help me with my project.

a simple html parser, looks for thumbnail tags and prints the thumbnail information

Quote: Originally Posted by kudos Hi, what do you want to get from your crawl? -kudos

hi kudos,

I want to write a crawler which will fetch the data like company name,turnover,product for which they are working for..and store into my database.

actually i have to submit a project,i have made simple html tags based crawler but want to make a dynamic simple web crawler.

your help is required!!!

Thanks in advance!!!

Varun

ok, webcrawlers, there is usually alot of 'ifs', but have a sketched out a very simple webcrawler that illustrates the idea (with comments!)



-kudos