I am trying to get data from the site https://bill.torrentpower.com/. I desire to input the city "Ahmedabad" and Service number "3031629" and extract the table which gives the bill details.
My code is simple
a<- postForm("https://bill.torrentpower.com/billdetails.aspx",
"ctl00$cph1$drpCity" = 1,
"ctl00$cph1$txtServiceNo" = "3031629",
.opts = list(ssl.verifypeer = FALSE)
)
write(a,file="a.html")
When I open the file a.html, I do not see the table containing the bill details. All other details are visible on a.html. My aim is to capture the tablular output as an R object.
The issue here is that the table is generated by the JavaScript code after the page has loaded and hence you will not get the content of the table.
This is a common problem with scraping information that has lots of dynamic content.
A work around this is to stimulate a web browser using RSelenium.
http://cran.r-project.org/web/packages/RSelenium/RSelenium.pdf
This will stimulate with web browser in your R session and you can navigate the webpages using various methdos ( see the user manual for info)
Personally, I find RSelenium with PhantomJS combination the most useful since I use a lot of JavaScript. Alternatively, if you find using R Syntax abit troublesome you may use PhantomJS on its own as well. http://phantomjs.org/
Related
I'm trying to scrape a number of tables from the following link:
'https://www.pro-football-reference.com/boxscores/201209050nyg.htm'
From what I can tell from trying a number of methods/packages I think R is failing to read in the entire url. Here's a few attempts I've made:
a <- getURL(url)
tabs <- readHTMLTable(a, stringsAsFactors = T)
and
x <- read_html(url)
y <- html_nodes(x,xpath= '//*[#id="div_home_snap_counts"]')
I've had success reading in the first two tables with both methods but after that I can't read in any others regardless of whether I use xpath or css. Does anyone have any idea why I'm failing to read in these later tables?
If you use a browser like Chrome you can go into settings and disable javascript. You will then see that only a few tables are present. The rest require javascript to run in order to load. Those are not being loaded, as displayed in browser, when you use your current method. Possible solutions are:
Use a method like RSelenium which will allow javascript to run
Inspect HTML of page to see if info is stored elsewhere and can be obtained from there. Sometimes info is retrieved from script tags, for example, where it is stored as json/javascript object
Monitor network traffic when refreshing page (F12 to open dev tools and then Network tab) and see if you can find the source where the additional content is being loaded from. You may find other endpoints you can use).
Looking at the page it seems that at least two of those missing tables (likely all) are actually stored in comments in the returned html, associated with divs having class placeholder; and that you need to remove either the comments marks, or use a method that allows for parsing comments. Presumably, when javascript runs these comments are converted to displayed content.
Here is an example from the html:
Looking at this answer by #alistaire, one method is as follows (shown for single example table as per above image)
library(rvest)
h <- read_html('https://www.pro-football-reference.com/boxscores/201209050nyg.htm')
df <- h %>% html_nodes(xpath = '//comment()') %>%
html_text() %>%
paste(collapse = '') %>%
read_html() %>%
html_node('#game_info') %>%
html_table()
I am looking to scrape some data from a chemical database using R, mainly name, CAS Number, and molecular weight for now. However, I am having trouble getting rvest to extract the information I'm looking for. This is the code I have so far:
library(rvest)
library(magrittr)
# Read HTML code from website
# I am using this format because I ultimately hope to pull specific items from several different websites
webpage <- read_html(paste0("https://pubchem.ncbi.nlm.nih.gov/compound/", 1))
# Use CSS selectors to scrape the chemical name
chem_name_html <- webpage %>%
html_nodes(".short .breakword") %>%
html_text()
# Convert the data to text
chem_name_data <- html_text(chem_name_html)
However, when I'm trying to create name_html, R only returns character (empty). I am using SelectorGadget to get the HTML node, but I noticed that SelectorGadget gives me a different node than what the Inspector does in Google Chrome. I have tried both ".short .breakword" and ".summary-title short .breakword" in that line of code, but neither gives me what I am looking for.
I have recently run into the same issues using rvest to scrape PubChem. The problem is that the information on the page is rendered using javascript as you are scrolling down the page, so rvest is only getting minimal information from the page.
There are a few workarounds though. The simplest way to get the information that you need into R is using an R package called webchem.
If you are looking up name, CAS number, and molecular weight then you can do something like:
library(webchem)
chem_properties <- pc_prop(1, properties = c('IUPACName', 'MolecularWeight'))
The full list of compound properties that can be extracted using this api can be found here. Unfortunately there isn't a property through this api to get CAS number, but webchem gives us another way to query that using the Chemical Translation Service.
chem_cas <- cts_convert(query = '1', from = 'CID', to = 'CAS')
The second way to get information from the page that is a bit more robust but not quite as easy to work with is by grabbing information from the JSON api.
library(jsonlite)
chem_json <-
read_json(paste0("https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/", "1", "/JSON/?response_type=save$response_basename=CID_", "1"))
With that command you'll get a list of lists, which I had to write a convoluted script to parse the information that I needed from the page. If you are familiar with JSON, you can parse far more information from the page, but not quite everything. For example, in sections like Literature, Patents, and Biomolecular Interactions and Pathways, the information in these sections will not fully show up in the JSON information.
The final and most comprehensive way to get all information from the page is to use something like Scrapy or PhantomJS to render the full html output of the PubChem page, then use rvest to scrape it like you originally intended. This is something that I'm still working on as it is my first time using web scrapers as well.
I'm still a beginner in this realm, but hopefully this helps you a bit.
I am trying to scrape some information from a web page using R. The only problem (so far) is that when I inspect the HTML object that was returned, I see that the key DIV element (from which I want to return data) has the message that it is loading.
The code I am using is below.
How can ensure that all elements on the web page have been rendered before harvesting the HTML.
library(xml2)
html <- xml2::read_html("https://www.holidayhouses.co.nz/")
lst_node <- xml_find_all(html, "//body/div[#class = 'MapView js-MapView']/h1")
lst_node
# returns <h1 class="LoadingMessage">Loading...</h1>
Thanks for any suggestions...
I am editing my answer as the two ideas might apply if you use the package RSelenium. It is not the fastest way for scraping, but it should do the job. What you can do with this package, is to use R to interact with your internet browser.
So once you use RSelenium to go tu the url, you can:
If you are confident that the div will load in a certain amount of time, then you can set some delay using Sys.sleep() before you save the div in lst_node
Iterating until lst_node!="Loading..." with a while loop
I am trying to screen scrape tennis results data (point by point data, not just final result) from this page using R.
http://www.scoreboard.com/au/match/wang-j-karlovic-i-2014/M1mWYtEF/#point-by-point;1
Using the regular R screen scraping functions like readlines(),htmlParseTree() etc I am able to scrape the source html for the page, but that does not contain the results data.
Is it possible to scrape all the text from the page, as if I were on the page in my browser and selected all and then copied?
That data is loaded using AJAX from http://d.scoreboard.com/au/x/feed/d_mh_M1mWYtEF_en-au_1, so R will not be able to just load it for you. However, because both use the code M1mWYtEF, you can go directly to the page that has the data you want. Using Chrome's devtools, I was able to see that the page sends a header of X-Fsign: SW9D1eZo that will let you access that page (you get a 401 Unauthorized error otherwise).
Here is R code for getting the html that holds the data you want from your example page:
library(httr)
page_code <- "M1mWYtEF"
linked_page <- paste0("http://d.scoreboard.com/au/x/feed/d_mh_",
page_code, "_en-au_1")
GET(linked_page, add_headers("X-Fsign" = "SW9D1eZo"))
There are a number of fairly detailed answers on SO which cover authenticated login to an aspx site and a download from it. As a complete n00b I haven't been able to find a simple explanation of how to get data from a web form
The following MWE is intended as an example only. And this question is more intended to teach me how to do it for a wider collection of webpages.
website :
http://data.un.org/Data.aspx?d=SNA&f=group_code%3a101
what I tried and (obviously) failed.
test=read.csv('http://data.un.org/Handlers/DownloadHandler.ashx?DataFilter=group_code:101;country_code:826&DataMartId=SNA&Format=csv&c=2,3,4,6,7,8,9,10,11,12,13&s=_cr_engNameOrderBy:asc,fiscal_year:desc,_grIt_code:asc')
giving me goobledegook with a View(test)
Anything that steps me through this or points me in the right direction would be very gratefully received.
The URL you are accessing using read.csv is returning a zipped file. You could download it
using httr say and write the contents to a temp file:
library(httr)
urlUN <- "http://data.un.org/Handlers/DownloadHandler.ashx?DataFilter=group_code:101;country_code:826&DataMartId=SNA&Format=csv&c=2,3,4,6,7,8,9,10,11,12,13&s=_cr_engNameOrderBy:asc,fiscal_year:desc,_grIt_code:asc"
response <- GET(urlUN)
writeBin(content(response, as = "raw"), "temp/temp.zip")
fName <- unzip("temp/temp.zip", list = TRUE)$Name
unzip("temp/temp.zip", exdir = "temp")
read.csv(paste0("temp/", fName))
Alternatively Hmisc has a useful getZip function:
library(Hmisc)
urlUN <- "http://data.un.org/Handlers/DownloadHandler.ashx?DataFilter=group_code:101;country_code:826&DataMartId=SNA&Format=csv&c=2,3,4,6,7,8,9,10,11,12,13&s=_cr_engNameOrderBy:asc,fiscal_year:desc,_grIt_code:asc"
unData <- read.csv(getZip(urlUN))
The links are being generated dynamically. The other problem is the content isn't actually at that link. You're making a request to a (very odd and poorly documented) API which will eventually return with the zip file. If you look in the Chrome dev tools as you click on that link you'll see the message and response headers.
There's a few ways you can solve this. If you know some javascript you can script a headless webkit instance like Phantom to load up these pages, simulate lick events and wait for a content response, then pipe that to something.
Alternately you may be able to finagle httr into treating this like a proper restful API. I have no idea if that's even remotely possible. :)