Utils Package Hidden Gems

readClipboard andwriteClipboard

One of my favorite duo of functions from utils is readCLipboard and writeClipboard. If you’re doing some manipulation to get a quick answer between R and Excel, these functions can come in handy. readClipboard reads in whatever is currently on the Clipboard.

For example, let’s copy a column of cells from Excel.

readClipboard in R from Excel

We can now run readClipboard() in R. The result of running this command is a vector containing the column of cells we just copied. Each cell corresponds to an element in the vector.

readClipboard result in R

Similarly, if we want to write a vector of elements to the clipboard, we can the writeClipboard command:

test <- c("write", "to", "clipboard")
writeClipboard(test)

Now, the vector test has been copied to the clipboard. If you paste the result in Excel, you’ll see a column of cells corresponding to the vector you just copied.

writeClipboard result in R

combn

The combn function is useful for getting the possible combinations of an input vector. For instance, let’s say we want to get all of the possible 2-element combinations of a vector, we could do this:

food <- c("apple", "grape", "orange", "pear", "peach", "banana") 
combn(food, 2)

combn get all combinations of a vector's elements in R

In general, the first parameter of combn is the vector of elements you want to get possible combinations from. The second parameter is the number of elements you want in each combination. So if you need to get all possible 3-element or 4-element combinations, you would just need to change this number to three or four.

combn(food, 3)
combn(food, 4)

We can also add a parameter called simplify to make the function return a list of each combination, rather than giving back a matrix output like above.

combn(food, 3, simplify = FALSE)

fileSnapshot

The fileSnapshot function is one R’s collection of file manipulation functions. To learn more about file manipulation and getting information on files in R, check out this post.

fileSnapshot will list and provide details about the files in a directory. This function returns a list of objects.

# get file snapshot of current directory
snapshot <- fileSnapshot()

# or file snapshot of another directory
snapshot <- fileSnapshot("C:/some/other/directory")

fileSnapshot returns a list, which here we will just call “snapshot”. The most useful piece of information can be garnered from this by referencing “info”:

snapshot$info

Here, snapshot$info is a data frame showing information about the files in the input folder parameter. Its headers include:

download.file

download.file does just what it sounds like – downloads a file from the internet to the destination provided in the function’s input. The first parameter is the URL of the file you wish to download. The second parameter is the name you want to give to the downloaded file. Below, we download a file and call it “census_data.csv”.

download.file("https://www2.census.gov/programs-surveys/popest/datasets/2010/2010-eval-estimates/cc-est2010-alldata.csv", "census_data.csv")

fix - modify an object on the fly

The utils package also has the ability to modify objects on the fly with the fix function. For instance, let’s say you define a function interactively, and you want to make some modification.

some_func <- function(num)
{
    3 * num + 1

}

Now, let’s modify the function with fix: fix(some_func):

fix function in r

When you call fix, it comes up with an editor allowing you to modify the definition of the function. You can also call fix to modify a vector or data frame.

fix(iris)

fix data frame in r