The operation absolute value for columns can be used to remove negative values from a column and replace them with their nonnegative values. The output results of the operation for each column cell (x) is the absolute value or modulus x of a real number x which is the nonnegative value of x; meaning x or x is x). A few examples:
 The absolute value of 7 is 7 (7 = 7)
 The absolute value of 7 is 7 (7 = 7)
 The absolute value of 0 is 0 (0 = 0)
The absolute value for columns operation can be applied to a column of a table via ILWISPython editor or via ILWIS main window, Toolbar and the Operatins tab. The required Python syntax is:
name of the output column = ilwis.Engine.do(name of the operation, input table name, input column name)
Example bellow, shows the Python syntax for deriving absolute values of column cells; where the input table name is mytable, the input column is mycolumn, abs is the internal name for this operation and absmycolumn is the name of the output column. Note that the input table includes the input column.
absmycolumn = ilwis.Engine.do('abs',“file:///C:/my director/mycolumn", "file:///C:/my director/mytable.tbt")
In general, the URL used in the Python syntax can be replaced with variable name generated by Python. For example: a table and a column can be opened in Python Editor as variables:
ta = ilwis.Table("file:///C:/my director/mytable.tbt")
cl = ta.column("mycolumn")
Once the variables are created via ILWISPython editor, then it can be used directly without quotation mark and the URL as the following:
absmycolumn = ilwis.Engine.do('abs', tb, cl)
