Base 
bivariate correlation 
Pearson 
cor(dfx2, method = "pearson") 
Base 
bivariate correlation 
Spearman 
cor(dfx2, method = "spearman") 
Base 
Multivariate correlation 
pearson 
cor(df, method = "pearson") 
Base 
Multivariate correlation 
Spearman 
cor(df, method = "spearman") 
Hmisc 
P value 

rcorr(as.matrix(data[,1:9]))[["P"]] 
Ggally 
heat map 

ggcorr(df) 

Multivariate plots 

cf code below 