How to create a data frame from text submitted in a textarea with FastRWeb
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In this article, I show you how to create a data.frame from a text submitted in a textarea field with FastRWeb.
Requirements
- FastRWeb installed
- Knowledge of webforms
?read.table- Experience in HTML5
Submit
This example needs two scripts. The first one contains the webform. I wrote a FastRWeb script in order to work in /var/FastRWeb/web.R/. This form could have been a static HTML page. Paste the code below in /var/FastRWeb/web.R/tablesubmit.R.
run <- function() {
out("<!doctype html><html lang='en'><head><title>Submit a Table</title>",
"<meta charset='UTF-8'/></head><body><header><h1>Submit a Table</h1>",
"<p>This is an example showing how to read a text posted in a ",
"<code>textarea</code> and create a data frame from it.</p></header>",
sep = "", eol = "")
out("<form action="https://r-bloggers.com/phplist/?p=subscribe&id=1" method="post" target="popupwindow">", sep = "", eol = "")
out("<p>Paste the table content in the text area below.</p>")
out("<textarea name='MyTable' rows=15 cols=80></textarea>")
out("<br/><input type='submit' /></form>")
out("</body></html>")
done()
}
Output
To retrieve the the submitted data, read them and create your data.frame, you’ll respectively use the functions parse.multipart(), textConnection() and read.table(). These last two are installed with R base. parse.multipart() is available if you have installed la version 1.1 de FastRWeb.
Paste the text below in /var/FastRWeb/web.R/textareatodf.R.
run <- function(MyTable) {
# HTML
out("<!doctype html><html lang='en'><head><title>Data Frame</title>",
"<meta charset='UTF-8'/></head><body><header><h1><code>textarea</code> ",
"to <code>data.frame</code></h1></header>", sep = "", eol = "")
# Retrieve the data in a 'multipart/form-data' form
if (grep("^multipart", request$c.type)) {
pars <- parse.multipart()
} else {
}
# Create the data frame
try(MyDF <- read.table(file = textConnection(pars$MyTable), header = FALSE,
sep = "\t"))
# HTML output
if (!exists("MyDF")) {
out("<h2>Something went wrong…</h2>",
"<p>Make sure your table has the same number of elements for each ",
"row.</p>", sep = "", eol = "")
} else {
out("<h2>Your data frame</h2><p>This is your data frame.</p>")
oprint(MyDF)
oprint(sapply(MyDF, class))
}
out("</body></html>")
done()
}
To run this script, go here : http://localhost/cgi-bin/R/tablesubmit
Testing
Copy and paste the data from à spreadsheet (either LibreOffice Calc or Excel). The non-ASCII characters are handled correctly if the users did not change their browser encoding. You may want to use the options read.table() such as sep, col.names or colClasses.
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