conditionalIterate

swordfish.function.conditionalIterate()

Supposing the iteration is based only on the previous result, for the k-th (k ∈ N+) record, the calculation logic is (where the column “factor” holds the results):

• cond[k] == true: factor[k] = trueValue

• cond[k] == false: factor[k] = falseIterFunc(factor)[k-1]

Note

If falseIterFunc is a window function, the iteration is based on multiple previous results.

Parameters:

• cond (Constant) – A conditional expression or a function with BOOLEAN return values. It must contain fields from the input table. Constants/constant expressions are not supported.

• trueValue (Constant) – The calculation formula.

• falseIterFunc (Constant) –

  The function for iteration, whose only parameter is the column from the output table. Currently, only the following functions are supported (use partial application to specify functions with multiple parameters):

  • Moving functions: tmove, tmavg, tmmax, tmmin, tmsum, mavg, mmax, mmin, mcount, msum;

  • Cumulative window functions: cumlastNot, cumfirstNot;

  • Order-sensitive functions: ffill, move.

  If cond returns true, the calculation of trueValue is triggered. If cond returns false, falseIterFunc is called for iteration.