How to Correlate one variable to all other variables on R [duplicate]

Question

I want to correlate one variable (say tyrosine) with all the other variables (about 200 other metabolites, like urea, glucose, inosine, etc) on R, and I'm not sure how to go about it. I'm new to R.

I've learned the pair function, but that pairs every metabolite in the range specified to the other.

Thanks!

Answer 1

similar to Marc in the box using the apply and column names

> set.seed(1)
> n=20
> df <- data.frame(tyrosine=runif(n), urea=runif(n), glucose=runif(n), 
  inosine=runif(n))

> apply(df,2, function(col)cor(col, df$tyrosine))

tyrosine       urea    glucose    inosine 
1.0000000 -0.2373854 -0.3672984 -0.3393602 

It's a good question, and pattern to know for data of reasonable size, as it's efficient if you only want tyrosine cors (what the OP specifically asked) to only calculate tyrosine cors (n time + space), not all vs all (~n^2 time + space).

Answer 2

In the following example, I simply split a data frame that contains all of the variables into two matrices. These can be entered into the cor function to obtain your correlation values:

set.seed(1)
n=20
df <- data.frame(tyrosine=runif(n), urea=runif(n), glucose=runif(n), inosine=runif(n))
df

COR <- cor(as.matrix(df[,1]), as.matrix(df[,-1]))
COR
#           urea    glucose    inosine
#[1,] -0.2373854 -0.3672984 -0.3393602