Evaluate DAT

From TouchDesigner 088 Wiki

Summary

The Evaluate DAT changes the cells of the incoming DAT using string-editing and math expressions. It outputs a table with the same number of rows and columns.

  • The Output menu set to Expressions causes the input cells to be evaluated as expressions. me.inputCell.val ($V in Tscript) is the value of the input cell.
  • When there is an expression in Formula, it is applied to all input cells.
  • The optional second input DAT is an array of expressions which are matched to the cells of the input, then evaluated and output. If there are fewer rows in the second DAT than the first, the expressions in the last row of the second input are repeated. If there are fewer columns in the second DAT than the first, the last column is repeated.
  • Expressions and Commands are optimized by storing a compiled internal version, which runs much faster. Use this where possible. If you are reusing expressions by repeating them in a table, having an input table with the few expressions you will cycle through separate from the data will also improve performance.

If the second DAT is one cell, like the Formula parameter, it applies its expression to all the input cells. A one-cell second DAT with me.inputCell.val+1 adds 1 to all the first input's cells.

If the second DAT is
me.inputCell.val me.inputCell.val
me.inputCell.val sin(me.inputCell.val)

then the first row and first column are left intact and the rest of the cells get their sin() computed.

EvaluateDAT ex.png

The Evaluate DAT maintains the format of the first input DAT (table or text) unless the Output Table Size parameter is used.

See also the Substitute DAT.

PythonIcon.png evaluateDAT_Class

Expressions

The Evaluate DAT can be used to (1) build strings or (2) do math operations.

me.inputCell refers to the corresponding input cell that is used to evaluate the current cell. evaluateDAT_Class has a list of members that refer to incoming data. You can use Python to fetch data, like op('datpath')[row,col] to access DAT data and op('choppath')['channame'][sampleindex] to access CHOP data. A few examples:

   # access data from a particular row from the input table at the currently evaluated column
   me.inputTable('rowname',me.inputCol)
   # prefix the data in the current cell the input row and column
   # a string in the first cell will be formatted as [0,0]:string
   '['+str(me.inputRow)+','+str(me.inputCol)+']:'+me.inputCell
   # add the numeric data in the current cell to numeric data from another table
   op('datpath")[me.inputRow,'colname'] + me.inputCell
   # concatenate the numeric data in the current cell to string data from another table with a space between
   op('datpath')[me.inputRow,'colname'] + ' ' + me.inputCell
   # concatenate the current row number to string data from another table with a space between
   op('datpath')[me.inputRow,'colname'] + ' ' + str(me.inputRow)
   # concatenate a sample at the currrent row index from a chop channel with the current cell
   me.inputCell + ':' + str(op('choppath')['channame'][me.inputRow])

See Working with DATs in Python and Working with CHOPS in Python for more examples of accessing data in other operators.


You can also use any Tscript Expression to fetch data, like `tab("tabpath",row,col)` and `chop("choppath")`. A list of local variables, such as $V for the value of the corresponding input cell, is available, and you can use other Tscript Variables like $F and $SYS_XRES.

A few Tscript expressions v() and vs() are special to the Evaluate DAT and can access all cells in the input. vs() differs from v() as it always output strings, not floats.

The expressions v(row,col) and vs(row,col) can use the local variables R (the cell's row) and C (the cell's column).

  • v($R,$C) is the same as $V.
  • v($C,$R) transposes the cells.
  • You could address relative rows/columns with $C, $C-1, $C+1, and address the cell at the first column with v($R,0). v will return the cell contents as floats. vs will return cell contents as strings.

The expressions that let you get at cells by row/column names are:

  • vr(rowname,colnum)
  • vc(rownum,colname)
  • vrc(rowname,colname)

and the string versions of the above:

  • vsr(rowname,colnum)
  • vsc(rownum,colname)
  • vsrc(rowname,colname)

Example: vrc("john","august")

The local variables NR and NC give the number of rows and columns of the input table.

Inputs

Input 2 Formula - Each cell should be a one line expression or command.

Parameters - Evaluate Page

Input Data DAT /dat - An alternative DAT table to be used in place of an input table.

Formula DAT /dat - An alternative DAT table to be used in place of a formula table.

Output /output - Determines what format will be used for output from the DAT.

  • Strings /string - Evaluates input data as strings, including expanding any variable values to full strings.
  • Expressions /expr - Evaluates input data as expressions. Compiled.
  • Command /expr - Execute input data as a command and output results. Compiled.
  • Input Data /data - Passes through data from first input without manipulation.
  • Formulae /formula - Passes through first input if there is no second input. Otherwise passes through second input. If the first input has more rows or columns than the second one, then the last row or column of the second is repeated to fill out the extra cells.


Output Table Size/outputsize - If the Output Table Size parameter is Strings, Expressions, or Commands, and there is a second input, you can choose the output table size to be either Input DAT or the Formula DAT. If the Formula DAT is chosen and its table size is greater than the input data table, then the last cell in each row or column will be used when evaluating the remaining formulas.

Monitor Data Dependencies /dependency - If the Output parameter is set to Strings or Expressions, the DAT will monitor any nodes used by the data, as well as check for time dependencies, and cook accordingly. This toggle is on by default. If you only want the DAT to cook based on input changes, you can turn this off to avoid unnecessary updates.

Convert Backslash Characters /backslash - Will convert things like \n to newlines, \t to tabs etc. Note that \n, \t will be converted to spaces if the input DAT is a table.

Parameters - Scope Page

Exclude First Row /xfirstrow - Forces the first row to be ignored even if it is not specified by the Select Rows settings.

Exclude First Column /xfirstcol - Forces the first column to be ignored even if it is not specified by the Select Cols settings.

Select Rows /extractrows - This parameter allows you to pick different ways of specifying the rows selected.

  • All - All rows selected.
  • by Name - Rows selected using Start Row Name and End Row Name parameters.
  • by Index - Rows selected using Start Row Index and End Row Index parameters.
  • by Start Name, End Index - Rows selected using Start Row Name and End Row Index parameters.
  • by Start Index, End Name - Rows selected using Start Row Index and End Row Name parameters.
  • by Values - Rows selected by specifying the row values explicitly.
  • by Condition - Rows selected by an expression to be evaluated for the from column.

Start Row Name /rownamestart - Specify the row name to start the selection range from.

Start Row Index /rowindexstart - Specify the row index to start the selection range from.

End Row Name /rownameend - Specify the row name to end the selection range.

End Row Index/rowindexend - Specify the row index to end the selection range.

Selected Row Values /rownames - Specify actual row names that you want to select. You can use pattern matching, for example row[1-4] will select all the rows names row1 thru row4.

Row Select Condition /rowexpr - Specify an expression that will be evaluated. If the expression evaluates to true, the row will be selected.

Expand the parameter and you will see that it is in expression mode.

SelectDAT rowselectexpr.png

By default, the Python expression is re.match('.*',me.inputCell.val) != None. '.*' means match any character multiple times, so this expression matches all values. If you want to match the parent's operator name followed by any numeric number you can use me.parent().name+'[0-9]*', where '[0-9]*' matches any numerical string. '.*'+parent().name+'.*' will match any cell that contains the operator's parent name. You can check Regular Expression Operations for additional information on how to use the Python Regular Expression module.

In Tscript, you can access the cell value with the local variable $V, and the row and column with $R and $C

From Column /fromcol - When selecting rows by values, this parameter selects which column to use when matching cell values to Selected Row Values to determine which rows are selected.


Select Cols /Select cols - This parameter allows you to pick different ways of specifying the columns selected.

  • All - All columns selected.
  • by Name - Columns selected using Start Col Name and End Col Name parameters.
  • by Index - Columns selected using Start Col Index and End Col Index parameters.
  • by Start Name, End Index - Columns selected using Start Col Name and End Col Index parameters.
  • by Start Index, End Name - Columns selected using Start Col Index and End Col Name parameters.
  • by Values - Columns selected by specifying the column values explicitly.
  • by Condition - Rows selected by an expression to be evaluated for the from row.

Start Col Name /colnamestart - Specify the column name to start the selection range from.

Start Col Index /colindexstart - Specify the column index to start the selection range from.

End Col Name /colnameend - Specify the column name to end the selection range.

End Col Index /colindexend - Specify the column index to end the selection range.

Selected Col Values /colnames - Specify actual column names that you want to select. You can use pattern matching, for example colvalue[1-4] will select all the columns named colvalue1 thru colvalue4.

Col Select Condition /colexpr - Specify an expression that will be evaluated. If the expression evaluates to true, the column will be selected. See Row Select Condition for more details.

From Row /fromrow - When extracting columns by Specified Names, this parameter selects which row to use when matching cell values to Selected Col Values to determine which columns are selected.


Variables

Local variables available are:

  • $V - input data value.
  • $R - input row being processed.
  • $C - input column being processed.
  • $FR - row of function used.
  • $FC - column of function used.
  • $NR - number of input rows.
  • $NC - number of input columns.

NOTE: if the second input DAT is omitted and no formula is specified, then only the $R, $C, $NR and $NC variables are available.