有r语言为什么还要下rstdudio

Answer 1

DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("PreRevDate0", typeof(decimal)));
DataColumn col = new DataColumn();
col.ColumnName = "PreRevDate1";
col.Expression = "ABS(Convert.ToInt32(PreRevDate0))";
col.DataType = typeof(decimal);
dt.Columns.Add(col);
DataRow dr = dt.NewRow();
dr["PreRevDate0"] = -1;
dt.Rows.Add(dr);