My goal is to get links to all challenges of Kaggle with their title. I am using the library rvest for it but I do not seem to come far. The nodes are empty when I am a few divs in.
I am trying to do it for the first challenge at first and should be able to transfer that to every entry afterwards.
The xpath of the first entry is:
/html/body/div[1]/div[2]/div/div/div[2]/div/div/div[2]/div[2]/div/div/div[2]/div/div/div[1]/a
My idea was to get the link via html_attr( , "href") once I am in the right tag.
My idea is:
library(rvest)
url = "https://www.kaggle.com/competitions"
kaggle_html = read_html(url)
kaggle_text = html_text(kaggle_html)
kaggle_node <- html_nodes(kaggle_html, xpath = "/html/body/div[1]/div[2]/div/div/div[2]/div/div/div[2]/div[2]/div/div/div[2]/div/div/div[1]/a")
html_attr(kaggle_node, "href")
I cant go past a certain div. The following snippet shows the last node I can access
node <- html_nodes(kaggle_html, xpath="/html/body/div[1]/div[2]/div")
html_attrs(node)
Once I go one step further with html_nodes(kaggle_html,xpath="/html/body/div[1]/div[2]/div/div"), the node will be empty.
I think the issue is that kaggle uses a smart list that expands the further I scroll down.
(I am aware that I can use %>%. I am saving every step so that I am able to access and view them more easily to be able to learn how it properly works.)
I solved the issue. I think that I can not access the full html code of the site from R because the table is loaded by a script which expands the table (thus the HTML) with a user scrolling through.
I resolved it, by expanding the table manually, downloading the whole HTML webpage and loading the local file.
Related
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$response_basename=CID_", "1"))
With that command you'll get a list of lists, which I had to write a convoluted script to parse the information that I needed from the page. If you are familiar with JSON, you can parse far more information from the page, but not quite everything. For example, in sections like Literature, Patents, and Biomolecular Interactions and Pathways, the information in these sections will not fully show up in the JSON information.
The final and most comprehensive way to get all information from the page is to use something like Scrapy or PhantomJS to render the full html output of the PubChem page, then use rvest to scrape it like you originally intended. This is something that I'm still working on as it is my first time using web scrapers as well.
I'm still a beginner in this realm, but hopefully this helps you a bit.
I'm trying to webscrape some soccer data. I'm able to loop through all of the necessary web pages, but I'm having trouble getting the data that I need from each page. I think the tables that hold the table are some form of Java, which makes it difficult.
I'm trying to get the goal times for each team from the following website:
http://www.scoreboard.com/uk/match/arsenal-west-brom-2014-2015/AyTNt38e/#match-summary|match-statistics;0|lineups;1
but I can't seem to distinguish between goals/cards/other events that are present. Can anyone help me, or is this simply a lost cause on this website?
My code to get the time of the first event (goal/cards/other) is :
library("RSelenium")
startServer()
mybrowser <- remoteDriver()
mybrowser$open()
mybrowser$navigate("http://www.scoreboard.com/uk/match/arsenal-west-brom-2014-2015/AyTNt38e/#match-summary|match-statistics;0|lineups;1")
x<-mybrowser$findElements(using = 'css selector', ".time-box")
x[[1]]$getElementText()
You need to pick a specific parent element that holds only and all the elements that you want. In this case, "#summary-content div.time-box" works as the CSS selector.
If you want the event type, e.g. goal vs card vs ..., then you want to use the CSS selector "#summary-content div.icon-box" and then look at the other class on the DIV element. soccer-ball for a goal, y-card for a yellow card, and so on. For example,
<div class="icon-box soccer-ball">
That should be enough to get you started. You should be able to get the rest of them yourself.
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'm doing a project for college that involves web scraping. I'm trying to get all the links of the players profiles in this website(http://www.atpworldtour.com/en/rankings/singles?rankDate=2015-11-02&rankRange=1-5001). I've tried to grab the links with the following code:
library(XML)
doc_parsed<-htmlTreeParse("ranking.html",useInternal =T)
root<-xmlRoot(doc_parsed)
hrefs1 = xpathSApply(root,fun=xmlGetAttr,"href",path='//a')
"ranking.html" is the saved link. When I run the code, it gives me a list with 6887 instead of the 5000 links of the players profiles.What should I do?
To narrow down to the links you want, you must include in your expression attibutes that are unique to the element you are after. The best and fastest way to go is using ids (which should be unique). Next best is using paths under elements with specific classes. For example:
hrefs1 <- xpathSApply(root,fun=xmlGetAttr, "href", path='//td[#class="player-cell"]/a')
By the way, the page you link to has at the moment exactly 2252 links, not 5000.
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/