Function for calculating pairwise correlations between b*c columns of data in a data frame

GetCorrs.R

# a = data frame
# b = list of variables in x
# c = list of variables in y
# method_ = one of pearson, spearman, kendall (or their abbreviations)
# output is a data frame with as many columns as b * c

GetCorrs <- function(a, b, c, method_) {
    dfout_ <- list()
    names <- list()
    names_ <- list()
    for(i in 1:length(b)) {
    dfout <- data.frame(r = rep(NA, length(c)), P = rep(NA, length(c)))
      for(j in 1:length(c)) {
        rout <- cor.test(a[, b[i]], a[, c[j]], alternative = "two.sided", method = method_)
        dfout[j, ] <- c(as.numeric(rout[[4]]), as.numeric(rout[[3]]))
        names[[j]] <- paste(names(a)[b[i]], names(a)[c[j]], sep="_")
      }
    dfout_[[i]] <- dfout
    names_[[i]] <- names
    }
dfout_df <- do.call(rbind, dfout_)
dfout_df$traits <- as.vector(sapply(names_, function(x) laply(x, identity)))
return(dfout_df)
}