Skip to main content

Simple Text Web Crawler

I put together a simple web crawler for R. It's useful if you are doing any text analysis and need to make .txt files from webpages. If you have a data frame of URLs it will cycle through them and grab all the websites. It strips out the HTML code. Then it saves each webpage as an individual text file.

Thanks to Rex Douglass, also.

 Enjoy (and please feel free to improve)

Comments

Unknown said…
Nice piece of code. Does what it is supposed to.

Do you have any suggestions to how one can delay the code with x seconds? When using the code for retrieving many pages from same server I am overloading the server giving me "bad" files with no text, and probably some angry hosts, which is not my intention.

I solved the problem by taking 5% of total n of pages at the time. Therefore i believe a solution would be if one could make count total number of pages in the input file and tell the code to only send like 50 requests or 5% of total n at the time.

Best
Kasper
Unknown said…
That's a good suggestion. I think I like it better than the approach I took later here.
Salim KHALIL said…
This comment has been removed by the author.
Salim KHALIL said…
You can use an R web crawler and scraper called RCrawler, it's designed to crawl, parse, store and extract contents of web page automatically.
install.packages("Rcrawler")
see manual for more detail here R web scraper

Popular posts from this blog

Dropbox & R Data

I'm always looking for ways to download data from the internet into R. Though I prefer to host and access plain-text data sets (CSV is my personal favourite) from GitHub (see my short paper on the topic) sometimes it's convenient to get data stored on Dropbox . There has been a change in the way Dropbox URLs work and I just added some functionality to the repmis R package. So I though that I'ld write a quick post on how to directly download data from Dropbox into R. The download method is different depending on whether or not your plain-text data is in a Dropbox Public folder or not. Dropbox Public Folder Dropbox is trying to do away with its public folders. New users need to actively create a Public folder. Regardless, sometimes you may want to download data from one. It used to be that files in Public folders were accessible through non-secure (http) URLs. It's easy to download these into R, just use the read.table command, where the URL is the file name...

Slide: one function for lag/lead variables in data frames, including time-series cross-sectional data

I often want to quickly create a lag or lead variable in an R data frame. Sometimes I also want to create the lag or lead variable for different groups in a data frame, for example, if I want to lag GDP for each country in a data frame. I've found the various R methods for doing this hard to remember and usually need to look at old blog posts . Any time we find ourselves using the same series of codes over and over, it's probably time to put them into a function. So, I added a new command– slide –to the DataCombine R package (v0.1.5). Building on the shift function TszKin Julian posted on his blog , slide allows you to slide a variable up by any time unit to create a lead or down to create a lag. It returns the lag/lead variable to a new column in your data frame. It works with both data that has one observed unit and with time-series cross-sectional data. Note: your data needs to be in ascending time order with equally spaced time increments. For example 199...

A Link Between topicmodels LDA and LDAvis

Carson Sievert and Kenny Shirley have put together the really nice LDAvis R package. It provides a Shiny-based interactive interface for exploring the output from Latent Dirichlet Allocation topic models. If you've never used it, I highly recommend checking out their XKCD example (this paper also has some nice background). LDAvis doesn't fit topic models, it just visualises the output. As such it is agnostic about what package you use to fit your LDA topic model. They have a useful example of how to use output from the lda package. I wanted to use LDAvis with output from the topicmodels package. It works really nicely with texts preprocessed using the tm package. The trick is extracting the information LDAvis requires from the model and placing it into a specifically structured JSON formatted object. To make the conversion from topicmodels output to LDAvis JSON input easier, I created a linking function called topicmodels_json_ldavis . The full function is below. To...