MOON - 2 months ago 5
R Question

What does c do in R?

Consider the code below:

``````k <- c(.5, 1)
``````

What does c do here? I think it must be a list or vector. If it is, how can I extend this vector to contain 1024 values?

In R, the `c()` function returns a vector (a one dimensional array).

``````k <- c(0.5, 1) # k is a vector
k[1] # is 0.5 (remember, R indices start on 1)
k[2] # is 1
``````

If you want to create a vector with 1024 entries (assuming 0.5 increments), you have at least two ways to do it:

``````# One way
k <- (1:1024) / 2 # this will be 0.5, 1, 1.5, 2, ... , 512
# Another way:
k <- seq(0.5, 512, 0.5)
``````

Also you can use `c()` to concatenate two vectors:

``````k <- c(0.5, 1)         # k = 0.5, 1
k <- c(k, 1.5)         # k = 0.5, 1, 1.5
k <- c(k, c(2, 2.5))   # k = 0.5, 1, 1.5, 2, 2.5
k <- c(k, k)           # k = 0.5, 1, 1.5, 2, 2.5, 0.5, 1, 1.5, 2, 2.5
``````

Please check the help for `c()` and `seq` function (in R: `?c` and `?seq`)

Reference:

Source (Stackoverflow)