Url Parsing in R Programming Language

Here’s the translation of the Go URL parsing example to R, formatted in Markdown suitable for Hugo:

Our URL parsing program demonstrates how to parse and extract information from URLs in R. Here’s the full source code:

library(httr)

# We'll parse this example URL, which includes a
# scheme, authentication info, host, port, path,
# query params, and query fragment.
s <- "postgres://user:pass@host.com:5432/path?k=v#f"

# Parse the URL and ensure there are no errors.
u <- parse_url(s)

# Accessing the scheme is straightforward.
print(u$scheme)

# User contains all authentication info; access
# username and password individually.
print(paste(u$username, u$password, sep = ":"))
print(u$username)
print(u$password)

# The host contains both the hostname and the port,
# if present. They are already split in R.
print(paste(u$hostname, u$port, sep = ":"))
print(u$hostname)
print(u$port)

# Here we extract the path and the fragment after
# the #.
print(u$path)
print(u$fragment)

# To get query params in a string of k=v format,
# use build_url. You can also access query params
# directly from the parsed URL.
print(build_url(u$query))
print(u$query)
print(u$query$k)

Running our URL parsing program shows all the different pieces that we extracted:

[1] "postgres"
[1] "user:pass"
[1] "user"
[1] "pass"
[1] "host.com:5432"
[1] "host.com"
[1] "5432"
[1] "/path"
[1] "f"
[1] "k=v"
$k
[1] "v"

[1] "v"

This example demonstrates how to use the httr package in R to parse URLs. The parse_url() function is used to break down the URL into its components, which can then be accessed individually. The build_url() function can be used to reconstruct the query string.

Note that R’s URL parsing capabilities are somewhat different from those in other languages. For example, R automatically separates the hostname and port, and provides direct access to query parameters. This makes some operations more straightforward in R compared to other languages.

Remember to install the httr package (install.packages("httr")) before running this code if you haven’t already done so.