## ŒEVAL Evaluate external expression

Implemented (as a system method) for the R external class only.

Syntax:

result „ objref.ŒEVAL string

The monadic ŒEVAL system method allows an arbitrary expression to be evaluated in the external environment (currently R only). It is provided as a more convenient form of the system function of the same name. The object reference must be an R session object.

The right argument is a text vector containing the expression. The result is the explicit result (if any) of evaluating the expression in the external environment. For example:

          r„'r' Œnew 'r'
          r.x„2 3½¼6         © x is an R variable
          r.x
    1 2 3
    4 5 6

          r.Œeval 'x[2,]'
    4 5 6
          r.Œeval 'mean(x[2,])'
    5

Note that the last line could be executed using the alternative syntax:

          'r' Œeval 'mean(x[2,])'
    5

Topic: APLX Help : Help on APL language : System Methods : ŒEVAL Evaluate external expression

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