renjin

Renjin: How to clear context?

As I understand, Renjin context contains variables with their values.

Suppose, I invoked this once:

engine.eval("df <- data.frame(x=1:10, y=(1:10)+rnorm(n=10))");
engine.eval("print(df)");
engine.eval("print(lm(y ~ x, df))");

How can I clear context so that invoking engine.eval("print(df)"); produces exception about unknown variable after clearing context?

I want to eval different calculations without mixing context and recreating engine.

Solution

  • The "context" you mean is I think the R global environment. Each instance of RenjinScriptEngine has its own, independent global environment.

    You can inspect, modify, and clear the values set it in the global environment using R base functions, like so:

    engine.eval("print(ls())");  // print all symbols in the global environment
engine.eval("rm(ls())");     // remove all symbols in the global environment 
                             // (that don't start with a "." )

engine.eval("rm(ls(all.names=TRUE))"); // remove everything

    You can also use the javax.script API to do the same:

    engine.getBindings(ScriptContext.ENGINE).clear();

    Depending on your use case, clearing the global environment may be sufficient, but keep in mind that a RenjinScriptEngine contains additional state.

    If you load packages and/or their namespaces via library(), require() or mypackage::fun(), that will affect the internal state of the RenjinScriptEngine.

    Other things that affect the Session-level (RenjinScriptEngine) state: