[r] How to access single elements in a table in R

How do I grab elements from a table in R.

My Data looks like this:

         V1     V2
1      12.448 13.919
2      22.242  4.606
3      24.509  0.176

etc...

I basically just want to grab elements individually. I'm getting confused with all the R terminology like vectors, and I just want to be able to get at the individual elements.

Is there a function where I can just do like data[v1][1] and get the element in row 1 column 1?

This question is related to r indexing

The answer is


Maybe not so perfect as above ones, but I guess this is what you were looking for.

data[1:1,3:3]    #works with positive integers
data[1:1, -3:-3] #does not work, gives the entire 1st row without the 3rd element
data[i:i,j:j]    #given that i and j are positive integers

Here indexing will work from 1, i.e,

data[1:1,1:1]    #means the top-leftmost element

?"[" pretty much covers the various ways of accessing elements of things.

Under usage it lists these:

x[i]
x[i, j, ... , drop = TRUE]
x[[i, exact = TRUE]]
x[[i, j, ..., exact = TRUE]]
x$name
getElement(object, name)

x[i] <- value
x[i, j, ...] <- value
x[[i]] <- value
x$i <- value

The second item is sufficient for your purpose

Under Arguments it points out that with [ the arguments i and j can be numeric, character or logical

So these work:

data[1,1]
data[1,"V1"]

As does this:

data$V1[1]

and keeping in mind a data frame is a list of vectors:

data[[1]][1]
data[["V1"]][1]

will also both work.

So that's a few things to be going on with. I suggest you type in the examples at the bottom of the help page one line at a time (yes, actually type the whole thing in one line at a time and see what they all do, you'll pick up stuff very quickly and the typing rather than copypasting is an important part of helping to commit it to memory.)