Most functions and graphs will require information in a data frame structure. However, this differs by package so conversions might be necessary.
df <- data.frame(id = letters[1:10], x = 1:10, y = 11:20)
class(df) # "data.frame"
str(df)
matrix <- matrix(nrow = 2, ncol = 2)
matrix
class(matrix) # "matrix" "array"
list <- list(1, "a", TRUE, 1+4i)
list
class(list) # "list"
is.list(list) # TRUE
df.matrix <- as.matrix(data.frame)
class(df.matrix) # "matrix" "array"
matrix.df <- data.frame(matrix)
class(matrix.df) # "data.frame"