Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I would first try to just scrape the links to the relevant data files and use the resulting information to construct the full download path that includes user logins and so on. As others have suggested, <code>lapply</code> would be convenient for batch downloading.</p> <p>Here's an easy way to extract the URLs. Obviously, modify the example to suit your actual scenario.</p> <p>Here, we're going to use the <code>XML</code> package to identify all the links available at the CRAN archives for the Amelia package (<a href="http://cran.r-project.org/src/contrib/Archive/Amelia/" rel="nofollow">http://cran.r-project.org/src/contrib/Archive/Amelia/</a>).</p> <pre><code>&gt; library(XML) &gt; url &lt;- "http://cran.r-project.org/src/contrib/Archive/Amelia/" &gt; doc &lt;- htmlParse(url) &gt; links &lt;- xpathSApply(doc, "//a/@href") &gt; free(doc) &gt; links href href href "?C=N;O=D" "?C=M;O=A" "?C=S;O=A" href href href "?C=D;O=A" "/src/contrib/Archive/" "Amelia_1.1-23.tar.gz" href href href "Amelia_1.1-29.tar.gz" "Amelia_1.1-30.tar.gz" "Amelia_1.1-32.tar.gz" href href href "Amelia_1.1-33.tar.gz" "Amelia_1.2-0.tar.gz" "Amelia_1.2-1.tar.gz" href href href "Amelia_1.2-2.tar.gz" "Amelia_1.2-9.tar.gz" "Amelia_1.2-12.tar.gz" href href href "Amelia_1.2-13.tar.gz" "Amelia_1.2-14.tar.gz" "Amelia_1.2-15.tar.gz" href href href "Amelia_1.2-16.tar.gz" "Amelia_1.2-17.tar.gz" "Amelia_1.2-18.tar.gz" href href href "Amelia_1.5-4.tar.gz" "Amelia_1.5-5.tar.gz" "Amelia_1.6.1.tar.gz" href href href "Amelia_1.6.3.tar.gz" "Amelia_1.6.4.tar.gz" "Amelia_1.7.tar.gz" </code></pre> <p>For the sake of demonstration, imagine that, ultimately, we only want the links for the 1.2 versions of the package.</p> <pre><code>&gt; wanted &lt;- links[grepl("Amelia_1\\.2.*", links)] &gt; wanted href href href "Amelia_1.2-0.tar.gz" "Amelia_1.2-1.tar.gz" "Amelia_1.2-2.tar.gz" href href href "Amelia_1.2-9.tar.gz" "Amelia_1.2-12.tar.gz" "Amelia_1.2-13.tar.gz" href href href "Amelia_1.2-14.tar.gz" "Amelia_1.2-15.tar.gz" "Amelia_1.2-16.tar.gz" href href "Amelia_1.2-17.tar.gz" "Amelia_1.2-18.tar.gz" </code></pre> <p>You can now use that vector as follows:</p> <pre><code>wanted &lt;- links[grepl("Amelia_1\\.2.*", links)] GetMe &lt;- paste(url, wanted, sep = "") lapply(seq_along(GetMe), function(x) download.file(GetMe[x], wanted[x], mode = "wb")) </code></pre> <hr> <h3>Update (to clarify your question in comments)</h3> <p>The last step in the example above <em>downloads</em> the specified files to your current working directory (use <code>getwd()</code> to verify where that is). If, instead, you know for sure that <code>read.csv</code> works on the data, you can also try to modify your anonymous function to read the files directly:</p> <pre><code>lapply(seq_along(GetMe), function(x) read.csv(GetMe[x], header = TRUE, sep = "|", as.is = TRUE)) </code></pre> <p>However, I think a <em>safer</em> approach might be to download all the files into a single directory first, and then use <code>read.delim</code> or <code>read.csv</code> or whatever works to read in the data, similar to as was suggested by @Andreas. I say <em>safer</em> because it gives you more flexibility in case files aren't fully downloaded and so on. In that case, instead of having to redownload everything, you would only need to download the files which were not fully downloaded.</p>
    singulars
    1. This table or related slice is empty.
    1. PORead list of file names from web into R
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USA5C1D2H2I1M1N2O1R2T1
    1. USA5C1D2H2I1M1N2O1R2T1
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThanks this looks like it will work great once I get the htmlParse to work. For some reason, with my URL I get the following error: "Error: XML content does not seem to be XML, nor to identify a file name" any ideas?
      singulars
      1. PO
      1. USMikeTP
    2. COI seemed to have moved past the "Error:XML..." issue by modifing the htmlParse as follows: doc <- htmlParse(readLines(url), asText=TRUE). I understand the logic to get "wanted" and "GetMe". However, what is happening in the lapply has got me a little confused, as I am not sure where the files being downloaded are stored or how to use the data contained within.
      singulars
      1. PO
      1. USMikeTP
    3. CO@MikeTP, the `lapply` step should be modified to suit your needs. In this example, since the files were binary, I just downloaded them to my working directory. If you know for sure that you can read them directly from the online source, then you can probably replace `download.file(...)` with your `read.csv(...)` command. This would read all of the files into a `list`, and from there, you can keep them as separate `data.frames` or, if the structure is all the same, you can `rbind` them into a single `data.frame`. Hope that helps!
      singulars
      1. PO
      1. USA5C1D2H2I1M1N2O1R2T1
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload