data.matrix to array

sample <- structure(list(X1.Lms = c(132500000L, 135700000L, 134100000L, 137400000L, 141300000L, 136300000L), Y1.Lms = c(132500000L, 150900000L, 136900000L, 147100000L, 144200000L, 153700000L), X2.Lms = c(114500000L, 114100000L, 113700000L, 119500000L, 115800000L, 118100000L), Y2.Lms = c(132000000L, 152000000L, 135400000L, 145600000L, 141300000L, 150200000L), X3.Lms = c(150100000L, 147500000L, 148700000L, 149500000L, 154000000L, 151700000L), Y3.Lms = c(121500000L, 142500000L, 129900000L, 143000000L, 135800000L, 146900000L ), X4.Lms = c(97600000L, 96900000L, 99600000L, 102400000L, 103900000L, 105500000L), Y4.Lms = c(123500000L, 143800000L, 127800000L, 136800000L, 132700000L, 143700000L), X5.Lms = c(164700000L, 161900000L, 164700000L, 169400000L, 171300000L, 168400000L ), Y5.Lms = c(107800000L, 128600000L, 115900000L, 128200000L, 122400000L, 135200000L), X6.Lms = c(77600000L, 78300000L, 76600000L, 84000000L, 83600000L, 83600000L), Y6.Lms = c(110400000L, 131200000L, 115100000L, 123400000L, 120800000L, 132000000L ), X7.Lms = c(181600000L, 178000000L, 183600000L, 186700000L, NA, 188900000L), Y7.Lms = c(81700000L, 100500000L, 87600000L, 106000000L, NA, 111600000L), X8.Lms = c(NA_integer_, NA_integer_, NA_integer_, NA_integer_, NA_integer_, NA_integer_), Y8.Lms = c(NA_integer_, NA_integer_, NA_integer_, NA_integer_, NA_integer_, NA_integer_ )), .Names = c("X1.Lms", "Y1.Lms", "X2.Lms", "Y2.Lms", "X3.Lms", "Y3.Lms", "X4.Lms", "Y4.Lms", "X5.Lms", "Y5.Lms", "X6.Lms", "Y6.Lms", "X7.Lms", "Y7.Lms", "X8.Lms", "Y8.Lms"), row.names = c(NA, 6L ), class = "data.frame")