XMM-Newton Science Analysis System


dal (dal-1.199) [xmmsas_20230412_1735-21.0.0]

Column

A column can be accessed and released again with the procedures

• column Return a handle to a column. Requires a table handle, the column name or number, the starting row of interest, the number of rows of interest, and the access mode.
• release Release the column. Requires the column handle.

The following example illustrates how to change the values in a column.

program modifyColumn
  use dal
  type(DataSetT) :: set
  type(TableT) :: tab
  type(ColumnT) :: col
  integer(kind=int32), dimension(:), pointer :: x

  set = dataSet("test.dat",Modify)
  tab = table(set,"test")
  col = column(tab,"x",0,0,Modify)
  x => int32Data(col)
  x = 124
  call release(col)
  call release(set)
end program

The following procedures can operator on a column handle:

• name Returns the name.
• number Returns the column number.
• dataType Returns the data type of the column.
• dimensions Returns the shape of each cell in the column.
• numberOfDimensions Returns the number of dimensions of each cell in the column.
• numberOfRows Returns the number of rows in the column.

To reduce the size of the column that is accessed in one go (and thereby reducing memory usage), one can select a certain range:

• columnSeek Set the range of interest. Requires a column handle, the starting row and the number of rows.

Note: the current implementation of the DAL does not support the column seek function.