First steps in R

First of all, install R from here. Once R is installed you can open it and start familiarising yourself with it.

In R you run code by selecting lines and pressing control+R (on windows) or cmd+enter (on mac). Lines starting with an ash sign (#) don’t “run”, so it’s a useful tool for writing comments or for deactivating bits of code without deleting them.

# R is a powerful calculator! Try:
3*2
10/15
sqrt(2) # square root of twosqrt() is the first R function you see! Functions apply to what's between the brackets.
sqrt() # no argument between the brackets? R gets angry. Don't anger R.
pi # useful
2^3 # two to the third power
exp(1) # this equals to e^1
log(1) # natural log
log(exp(1))
log10(10) # decimal log

You can save results. Just give them a name as follows:

myfirstRobject <- 10/15
myfirstRobject
mysecondone <- 11*11
myfirstRobject + mysecondone

Do you want to apply a calculation to more than one number at a time? You can save the numbers in an R object called “vector”:

somenumbers <- c(1,2,3,5,7,11)
somenumbers*2

A bunch of vectors together is called a matrix. Unless you give each vector in the matrix a name. In that case they form an object called a “data-frame” (namely a dataset) and each vector becomes one of the data-frame’s columns. Here’s how you create one:

myfirstdf <- data.frame(mynumbers = somenumbers)
# now create a new column for the data.frame:
myfirstdf$timestwo <- myfirstdf$mynumbers * 2

Do you want to export a data.frame? Easy peasy!

write.csv(myfirstdf, "~/Desktop/output.csv")

I am working on a Mac. You may have to type directories in a slightly different way in Windows.