I have this table 
I would like the NAs in columns 2:6 to be "Ag", and those in 7:12 to be "Non-Ag" but keep running into errors.
The dput is:
structure(list(X1 = c("Treatment", NA, "Long Term Arm", NA, "Short Term Arm", NA), X2 = c(NA, "# Ent.", "4.36", "[2.93]", "0.49", "[2.6]"), X3 = c(NA, "Rev.", "8521.72", "[5523.36]", "10174.38∗∗", "[5136.73]"), X4 = c("Ag", "Costs", "5277.01", "[3785.31]", "5966.48∗", "[3464.9]"), X5 = c(NA, "Net-Rev.", "2137.42", "[4615.71]", "4368.46", "[4033.6]"), X6 = c(NA, "Assets", "29779.09∗∗∗", "[10833.07]", "15558.74∗", "[8977.02]" ), X7 = c(NA, "# Ent.", "5.57∗∗∗", "[1.81]", "2.90∗∗", "[1.35]"), X8 = c(NA, "Rev.", "52857.68∗∗", "[22776.31]", "13003.09", "[14778.92]"), X9A = c("Non-Ag", "Costs", "26778.28∗", "[15747.31]", "2530.93", "[9819.96]"), X9B = c(NA, "Net-Rev.", "26088.63∗∗", "[11245.63]", "10456.25", "[6713.02]"), X12 = c(NA, "Assets", "6271.58", "[6082.45]", "883.07", "[4328.38]" )), row.names = c(NA, -6L), class = c("tbl_df", "tbl", "data.frame"))