There are 2 parts of my questions as I explored 2 methods in this exercise, however I succeed in none. Greatly appreciated if someone can help me out.
[PART 1:]
I am attempting to scrape data from a webpage on Singapore Stock Exchange https://www2.sgx.com/derivatives/negotiated-large-trade containing data stored in a table. I have some basic knowledge of scraping data using (rvest). However, using Inspector on chrome, the html hierarchy is much complex then I expected. I'm able to see that the data I want is hidden under < div class= "table-container" >,and here's what I've tied:
library(rvest)
library(httr)
library(XML)
SGXurl <- "https://www2.sgx.com/derivatives/negotiated-large-trade"
SGXdata <- read_html(SGXurl, stringsASfactors = FALSE)
html_nodes(SGXdata,".table-container")
However, nothing has been picked up by the code and I'm doubt if I'm using these code correctly.
[PART 2:]
As I realize that there's a small "download" button on the page which can download exactly the data file i want in .csv format. So i was thinking to write some code to mimic the download button and I found this question Using R to "click" a download file button on a webpage, but i'm unable to get it to work with some modifications to that code.
There's a few filtera on the webpage, mostly I will be interested downloading data for a particular business day while leave other filters blank, so i've try writing the following function:
library(httr)
library(rvest)
library(purrr)
library(dplyr)
crawlSGXdata = function(date){
POST("https://www2.sgx.com/derivatives/negotiated-large-trade",
body = NULL
encode = "form",
write_disk("SGXdata.csv")) -> resfile
res = read.csv(resfile)
return(res)
}
I was intended to put the function input "date" into the “body” argument, however i was unable to figure out how to do that, so I started off with "body = NULL" by assuming it doesn't do any filtering. However, the result is still unsatisfactory. The file download is basically empty with the following error:
Request Rejected
The requested URL was rejected. Please consult with your administrator.
Your support ID is: 16783946804070790400
The content is loaded dynamically from an API call returning json. You can find this in the network tab via dev tools.
The following returns that content. I find the total number of pages of results and loop combining the dataframe returned from each call into one final dataframe containing all results.
library(jsonlite)
url <- 'https://api.sgx.com/negotiatedlargetrades/v1.0?order=asc&orderby=contractcode&category=futures&businessdatestart=20190708&businessdateend=20190708&pagestart=0&pageSize=250'
r <- jsonlite::fromJSON(url)
num_pages <- r$meta$totalPages
df <- r$data
url2 <- 'https://api.sgx.com/negotiatedlargetrades/v1.0?order=asc&orderby=contractcode&category=futures&businessdatestart=20190708&businessdateend=20190708&pagestart=placeholder&pageSize=250'
if(num_pages > 1){
for(i in seq(1, num_pages)){
newUrl <- gsub("placeholder", i , url2)
newdf <- jsonlite::fromJSON(newUrl)$data
df <- rbind(df, newdf)
}
}
Related
Thanks in advance for any feedback.
As part of my dissertation I'm trying to scrape data from the web (been working on this for months). I have a couple issues:
-Each document I want to scrape has a document number. However, the numbers don't always go up in order. For example, one document number is 2022, but the next one is not necessarily 2023, it could be 2038, 2040, etc. I don't want to hand go through to get each document number. I have tried to wrap download.file in purrr::safely(), but once it hits a document that does not exist it stops.
-Second, I'm still fairly new to R, and am having a hard time setting up destfile for multiple documents. Indexing the path for where to store downloaded data ends up with the first document stored in the named place, the next document as NA.
Here's the code I've been working on:
base.url <- "https://www.europarl.europa.eu/doceo/document/"
document.name.1 <- "P-9-2022-00"
document.extension <- "_EN.docx"
#document.number <- 2321
document.numbers <- c(2330:2333)
for (i in 1:length(document.numbers)) {
temp.doc.name <- paste0(base.url,
document.name.1,
document.numbers[i],
document.extension)
print(temp.doc.name)
#download and save data
safely <- purrr::safely(download.file(temp.doc.name,
destfile = "/Users/...[i]"))
}
Ultimately, I need to scrape about 120,000 documents from the site. Where is the best place to store the data? I'm thinking I might run the code for each of the 15 years I'm interested in separately, in order to (hopefully) keep it manageable.
Note: I've tried several different ways to scrape the data. Unfortunately for me, the RSS feed only has the most recent 25. Because there are multiple dropdown menus to navigate before you reach the .docx file, my workaround is to use document numbers. I am however, open to more efficient way to scrape these written questions.
Again, thanks for any feedback!
Kari
After quickly checking out the site, I agree that I can't see any easier ways to do this, because the search function doesn't appear to be URL-based. So what you need to do is poll each candidate URL and see if it returns a "good" status (usually 200) and don't download when it returns a "bad" status (like 404). The following code block does that.
Note that purrr::safely doesn't run a function -- it creates another function that is safe and which you then can call. The created function returns a list with two slots: result and error.
base.url <- "https://www.europarl.europa.eu/doceo/document/"
document.name.1 <- "P-9-2022-00"
document.extension <- "_EN.docx"
#document.number <- 2321
document.numbers <- c(2330:2333,2552,2321)
sHEAD = purrr::safely(httr::HEAD)
sdownload = purrr::safely(download.file)
for (i in seq_along(document.numbers)) {
file_name = paste0(document.name.1,document.numbers[i],document.extension)
temp.doc.name <- paste0(base.url,file_name)
print(temp.doc.name)
print(sHEAD(temp.doc.name)$result$status)
if(sHEAD(temp.doc.name)$result$status %in% 200:299){
sdownload(temp.doc.name,destfile=file_name)
}
}
It might not be as simple as all of the valid URLs returning a '200' status. I think in general URLs in the range 200:299 are ok (edited answer to reflect this).
I used parts of this answer in my answer.
If the file does not exists, tryCatch simply skips it
library(tidyverse)
get_data <- function(index) {
paste0(
"https://www.europarl.europa.eu/doceo/document/",
"P-9-2022-00",
index,
"_EN.docx"
) %>%
download.file(url = .,
destfile = paste0(index, ".docx"),
mode = "wb",
quiet = TRUE) %>%
tryCatch(.,
error = function(e) print(paste(index, "does not exists - SKIPS")))
}
map(2000:5000, get_data)
I'm attempting web scraping. Before posting my question, I looked up several similar questions such as this, and this. However, I still get stuck in my problem.
Speicifically, I'm trying to extract the listed prices on a second-hand cars website. # In case you are unable to see the data because you're not a registered user of this website, I also attached the screenshot of this website's html elements:
the screen shot.
The code I executed are:
library(httr)
library(XML)
url <- "https://www.sahibinden.com/vasita?query_text_mf=alfa+romeo+giulietta&query_text=alfa+romeo+giulietta"
htmlresponse <- GET(url)
htmlcontent <- content(htmlresponse, as="text")
parsedhtml <- htmlParse(htmlcontent, asText = TRUE)
# The above is just following the conventions, and seems okay.
prices <- xpathSApply(doc = parsedhtml, path = "//div/td[#class='searchResultsPriceValue']", fun = xmlValue)
# This command returned me an empty list.
Can someone have a look and give me some advices? Thank you very much!
I am rather new in webscraping but need data for my PhD project. For this, I am extracting data on different activities of MEPs from the European Parliament's website. Concretely, and where I have problems, I would like to extract the title and especially the link underlying the title of each speech from a MEP's personal page. I use a code that already worked fine several times, but here I do not succeed in getting the link, but only the title of the speech. For the links I get the error message "subscript out of bounds". I am working with RSelenium because there are several load more buttons on the individual pages I have to click first before extracting the data (which makes rvest a complicated option as far as I see it).
I am basically trying to solve this for days now, and I really do not know how to get further. I have the impression that the css selector is not actually capturing the underlying link (as it extracts the title without problems), but the class has a compounded name ("ep-a_heading ep-layout_level2") so it is not possible to go via this way either. I tried Rvest as well (ignoring the problem I would then have for the load more--button) but I still do not get to those links.
```{r}
library(RSelenium)
library(wdman)
library(rvest, warn.conflicts=FALSE)
library(stringr)
server <- phantomjs(port=7005L)
browser <- remoteDriver(browserName = "phantomjs", port=7005L)
## this is one of the urls I will use, there are others, constructed all
##the same way and all with the same problem
url <- 'http://www.europarl.europa.eu/meps/en/124936/MARIA_ARENA/all-
activities/plenary-speeches/8'
browser$open()
browser$navigate(url)
## now I identify the load more button and click on it as long as there
##is a "load more" button on the page
more <- browser$findElement(using = "css", value=".erpl-activities-
loadmore-button .ep_name")
while (!is.null(more)){
more$clickElement()
Sys.sleep(1)}
## I get an error message doing this in the end but it is working anyway
##(yes, I really am a beginner!)
##Now, what I want to extract are the title of the speech and most
##importantly: the URL.
links <- browser$findElements(using="css", ".ep-layout_level2 .ep_title")
length(links)
## there are 128 Speeches listed on the page
URL <- rep(NA, length(links))
Title <- rep(NA, length(links))
## after having created vectors to store the results, I apply the loop
##function that had worked fine already many times to extract the data I
##want
for (i in 1:length(links)){
URL[i] <- links[[i]]$getElementAttribute('href')[[1]]
Title[i] <- links[[i]]$getElementText()[[1]]
}
speeches <- data.frame(Title, URL)
For this example there 128 speeches on the page, so in the end I would need a table with 128 titles and links. The code works fine when I only try for the title but for the URLs I get:
`"Error in links[[i]]$getElementAttribute("href")[[1]] : subscript out of bounds"`
Thank you very much for your help, I already read many posts on subscript out of bounds issues in this forum, but unfortunately I still couldn't solve the problem.
Have a great day!
I don't seem to have a problem using rvest to get that info. No need for overhead of using selenium. You want to target the a tag child of that class i.e. .ep-layout_level2 a in order to be able to access an href attribute. Same selector would apply for selenium.
library(rvest)
library(magrittr)
page <- read_html('https://www.europarl.europa.eu/meps/en/124936/MARIA_ARENA/all-activities/plenary-speeches/8')
titles <- page %>% html_nodes('.ep-layout_level2 .ep_title') %>% html_text() %>% gsub("\\r\\n\\t+", "", .)
links <- page %>% html_nodes('.ep-layout_level2 a') %>% html_attr(., "href")
results <- data.frame(titles,links)
Here you have a working solution based on the code you provided:
library(RSelenium)
library(wdman)
library(rvest, warn.conflicts=FALSE)
library(stringr)
server <- phantomjs(port=7005L)
browser <- remoteDriver(browserName = "phantomjs", port=7005L)
## this is one of the urls I will use, there are others, constructed all
##the same way and all with the same problem
url <- 'http://www.europarl.europa.eu/meps/en/124936/MARIA_ARENA/all-activities/plenary-speeches/8'
browser$open()
browser$navigate(url)
## now I identify the load more button and click on it as long as there
##is a "load more" button on the page
more <- browser$findElement(using = "class",value= "erpl-activity-loadmore-button")
while ((grepl("erpl-activity-loadmore-button",more$getPageSource(),fixed=TRUE)){
more$clickElement()
Sys.sleep(1)}
## I get an error message doing this in the end but it is working anyway
##(yes, I really am a beginner!)
##Now, what I want to extract are the title of the speech and most
##importantly: the URL.
links <- browser$findElements(using="class", "ep-layout_level2")
## there are 128 Speeches listed on the page
URL <- rep(NA, length(links))
Title <- rep(NA, length(links))
## after having created vectors to store the results, I apply the loop
##function that had worked fine already many times to extract the data I
##want
for (i in 1:length(links)){
l=links[[i]]$findChildElement(using="css","a")
URL[i] <-l$getElementAttribute('href')[[1]]
Title[i] <- links[[i]]$getElementText()[[1]]
}
speeches <- data.frame(Title, URL)
speeches
The main differences are:
In the first findElement I use value= erpl-activity-loadmore-button. Indeed the documentation says that you can not look at multiple class values at once
Same when it comes to look for the links
In the final loop, you need fist to select the link element in the
div you selected and then read the href attribute
To answer your question about the error message in comments after the while loop: When you pressed enough time the "Load more" buttons it become invisible, but still exists. So when you check for !is.null(more)it is TRUE because the button still exists, but when you try to click it you get and error message because it is invisible. So you can fix it by checking it it is visible or note.
I would like to use a website from R. The website is http://soundoftext.com/ where I can download WAV. files with audios from a given text and a language (voice).
There are two steps to download the voice in WAV:
1) Insert text and Select language. And Submit
2) On the new window, click Save and select folder.
Until now, I could get the xml tree, convert it to list and modify the values of text and language. However, I don't know how to convert the list to XML (with the new values) and execute it. Then, I would need to do the second step too.
Here is my code so far:
require(RCurl)
require(XML)
webpage <- getURL("http://soundoftext.com/")
webpage <- readLines(tc <- textConnection(webpage)); close(tc)
pagetree <- htmlTreeParse(webpage, error=function(...){}, useInternalNodes = TRUE)
x<-xmlToList(pagetree)
# Inserting word
x$body$div$div$div$form$div$label$.attrs[[1]]<-"Raúl"
x$body$div$div$div$form$div$label$.attrs[[1]]
# Select language
x$body$div$div$div$form$div$select$option$.attrs<-"es"
x$body$div$div$div$form$div$select$option$.attrs
I have follow this approach but there is an error with "tag".
UPDATED: I just tried to use rvest to download the audio file, however, it does not respond or trigger anything. What am I doing wrong (missing)?
url <- "http://soundoftext.com/"
s <- html_session(url)
f0 <- html_form(s)
f1 <- set_values(f0[[1]], text="Raúl", lang="es")
attr(f1, "type") <- "Submit"
s[["fields"]][["submit"]] <- f1
attr(f1, "Class") <- "save"
test <- submit_form(s, f1)
I see nothing wrong with your approach and it was worth a try.. that's what I'd write too.
The page is somewhat annoying in that uses jquery to append new divs at each request. I still think that should be possible to do with rvest, but I found a fun workaround using the httr package:
library(httr)
url <- "http://soundoftext.com/sounds"
fd <- list(
submit = "save",
text = "Banana",
lang="es"
)
resp<-POST(url, body=fd, encode="form")
id <- content(resp)$id
download.file(URLencode(paste0("http://soundoftext.com/sounds/", id)), destfile = 'test.mp3')
Essentially when it send the POST request to the server, an ID come back, if we simply GET that id when can download the file.
Creator of Sound of Text here. Sorry it took so long for me to find this post.
I just redesigned Sound of Text, so your html parsing probably won't work anymore.
However, there is now an API that you can use which should make things considerably easier for you.
You can find the documentation here: https://soundoftext.com/docs
I apologize if it's not very good. Please let me know if you have any questions.
I'm stuck on this one after much searching....
I started with scraping the contents of a table from:
http://www.skatepress.com/skates-top-10000/artworks/
Which is easy:
data <- data.frame()
for (i in 1:100){
print(paste("page", i, "of 100"))
url <- paste("http://www.skatepress.com/skates-top-10000/artworks/", i, "/", sep = "")
temp <- readHTMLTable(stringsAsFactors = FALSE, url, which = 1, encoding = "UTF-8")
data <- rbind(data, temp)
} # end of scraping loop
However, I need to additionally scrape the detail that is contained in a pop-up box when you click on each name (and on the artwork title) in the list on the site.
I can't for the life of me figure out how to pass the breadcrumb (or artist-id or painting-id) through in order to make this happen. Since straight up using rvest to access the contents of the nodes doesn't work, I've tried the following:
I tried passing the painting id through in the url like this:
url <- ("http://www.skatepress.com/skates-top-10000/artworks/?painting_id=576")
site <- html(url)
But it still gives an empty result when scraping:
node1 <- "bread-crumb > ul > li.activebc"
site %>% html_nodes(node1) %>% html_text(trim = TRUE)
character(0)
I'm (clearly) not a scraping expert so any and all assistance would be greatly appreciated! I need a way to capture this additional information for each of the 10,000 items on the list...hence why I'm not interested in doing this manually!
Hoping this is an easy one and I'm just overlooking something simple.
This will be a more efficient base scraper and you can get progress bars for free with the pbapply package:
library(xml2)
library(httr)
library(rvest)
library(dplyr)
library(pbapply)
library(jsonlite)
base_url <- "http://www.skatepress.com/skates-top-10000/artworks/%d/"
n <- 100
bind_rows(pblapply(1:n, function(i) {
mutate(html_table(html_nodes(read_html(sprintf(base_url, i)), "table"))[[1]],
`Sale Date`=as.Date(`Sale Date`, format="%m.%d.%Y"),
`Premium Price USD`=as.numeric(gsub(",", "", `Premium Price USD`)))
})) -> skatepress
I added trivial date & numeric conversions.
I belive your main issue is that the site requires a login to get the additional data. You should give that (i.e. logging in) a shot using httr and grab the wordpress_logged_inXXXXXXX… cookie from that endeavour. I just grabbed it from inspecting the session with Developer Tools in Chrome and that will also work for you (but it's worth the time to learn how to do it via httr).
You'll need to scrape two additional <a … tags from each table row. The one for "artist" looks like:
Pablo Picasso
You can scrape the contents with:
POST("http://www.skatepress.com/wp-content/themes/skatepress/scripts/query_artist.php",
set_cookies(wordpress_logged_in_XXX="userid%XXXXXreallylongvalueXXXXX…"),
encode="form",
body=list(id="pab_pica_1881"),
verbose()) -> artist_response
fromJSON(content(artist_response, as="text"))
(The return value is too large to post here)
The one for "artwork" looks like:
Les femmes d′Alger (Version ′O′)
and you can get that in similar fashion:
POST("http://www.skatepress.com/wp-content/themes/skatepress/scripts/query_artwork.php",
set_cookies(wordpress_logged_in_XXX="userid%XXXXXreallylongvalueXXXXX…"),
encode="form",
body=list(id=576),
verbose()) -> artwork_response
fromJSON(content(artwork_response, as="text"))
That's not huge but I won't clutter the response with it.
NOTE that you can also use rvest's html_session to do the login (which will get you cookies for free) and then continue to use that session in the scraping (vs read_html) which will mean you don't have to do the httr GET/PUT.
You'll have to figure out how you want to incorporate that data into the data frame or associate it with it via various id's in the data frame (or some other strategy).
You can see it call those two php scripts via Developer Tools and it also shows the data it passes in. I'm also really shocked that site doesn't have any anti-scraping clauses in their ToS but they don't.