Sparse matrices

(흔히 넓은 지역에 분포된 정도가) 드문, (밀도가) 희박한

sparse  matrix

희소 행렬 :  행렬 내부의 원소가 거의 0이고  실제 값이 들어간 건 몇 개 안 되는 행렬입니다

In numerical analysis and computer science, a sparse matrix or sparse array is a matrix in which most of the elements are zero.
By contrast, if most of the elements are nonzero, then the matrix is considered dense.

rowse[3]> m1 <- ranger(data=ddMatrix, dependent.variable.name = "y", formula = as.formula(y ~ .), mtry=2 , num.trees = 1000, importance = "impurity", probability = T)
Error in ranger(data = ddMatrix, dependent.variable.name = "y", formula = as.formula(y ~  : 
  Error: Sparse matrices only supported with alternative interface. Use dependent.variable.name instead of formula.

ddMatrix <- Matrix(data.matrix(dd), sparse = TRUE)
m0 <- ranger(data=ddMatrix, dependent.variable.name = “y”, mtry = 2, num.trees = 1000, importance = “impurity”, probability = T)
m0$terms <- terms(as.formula(y ~ .), data = dd)
m0$mode <- “matrix”