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POReturning a function in a list, from a function
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  1. POReturning a function in a list, from a function
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    copied!<p>I searched for this question, but found answers that weren't specific enough.</p> <p>I'm cleaning up old code and I'm trying to make sure that the following is relatively clean, and hoping that it won't bite me on the rear later on.</p> <p>My question is about passing a function through a function. Look at the "y" part of the following plot statement. The <code>goo(df)[[1]](x)</code> thing works, but am I asking for trouble in any way? If so, is there a cleaner way? </p> <p>Also, if the <code>goo()</code> function is called many many times, for instance in a Monte Carlo analysis, will this load up R's internals or possibly cause some type of environment issues?</p> <p>Edit (02/21/2011) --- The following code is just an example. The real function "goo" has a lot of code before it gets to the approxfun() statement.</p> <pre><code>#Build a dataframe df &lt;- data.frame(a=c(1, 2, 3, 4, 5), b=c(4, 3, 1, 2, 6)) #Build a function that passes a function goo &lt;- function(inp.df) { out.fun &lt;- approxfun(x=inp.df$a, y=inp.df$b, yright=max(inp.df$b), method="linear", f=1) list(out.fun, inp.df$a[5], inp.df$b[5]) } #Set up the plot range x &lt;- seq(1, 4.3, 0.01) #Plot the function plot(x, goo(df)[[1]](x), type="l", xlim=c(0, goo(df)[[2]]), ylim=c(0, goo(df)[[3]]), lwd=2, col="red") grid() goo(df) [[1]] function (v) .C("R_approxfun", as.double(x), as.double(y), as.integer(n), xout = as.double(v), as.integer(length(v)), as.integer(method), as.double(yleft), as.double(yright), as.double(f), NAOK = TRUE, PACKAGE = "stats")$xout &lt;environment: 0219d56c&gt; [[2]] [1] 5 [[3]] [1] 6 </code></pre>
 

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