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    <p>If you don't need names and your list is one level deep, then if you can beat</p> <pre><code>.Internal(unlist(your_list, FALSE, FALSE)) </code></pre> <p>I will vote up everything you do on SO for the next 1 year!!!</p> <p>[Update: if non-unique names are needed and the list is not recursive, here is a version which improves over the unlist 100 times</p> <pre><code> myunlist &lt;- function(l){ names &lt;- names(l) vec &lt;- unlist(l, F, F) reps &lt;- unlist(lapply(l, length), F, F) names(vec) &lt;- rep(names, reps) vec } myunlist(list(a=1:3, b=2)) a a a b 1 2 3 2 &gt; tl &lt;- list(a = 1:20000, b = 1:5000, c = 2:30) &gt; system.time(for(i in 1:200) unlist(tl)) user system elapsed 22.97 0.00 23.00 &gt; system.time(for(i in 1:200) myunlist(tl)) user system elapsed 0.2 0.0 0.2 &gt; system.time(for(i in 1:200) unlist(tl, F, F)) user system elapsed 0.02 0.00 0.02 </code></pre> <p>]</p> <p>[Update2: Responce to challenge Nr3 from Richie Cotton. </p> <pre><code>bigList3 &lt;- replicate(500, rnorm(1e3), simplify = F) unlist_vit &lt;- function(l){ names(l) &lt;- NULL do.call(c, l) } library(rbenchmark) benchmark(unlist = unlist(bigList3, FALSE, FALSE), rjc = unlist_rjc(bigList3), vit = unlist_vit(bigList3), order = "elapsed", replications = 100, columns = c("test", "relative", "elapsed") ) test relative elapsed 1 unlist 1.0000 2.06 3 vit 1.4369 2.96 2 rjc 3.5146 7.24 </code></pre> <p>]</p> <p>PS: I assume a "big fish" is the one with more reputation than you. So I am pretty much small here :). </p>
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    1. CO+1 It is probably not significant, but in my test your version was a bit faster than @ucfagls'. Yet the biggest speedup is gathered from use.names=F.
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    2. COI understood from Roman's question that his desire was to replace the build-in "unlist" with something smarter. As far as I am concerned this is not possible when names are not required.
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    3. CONow that's an offer a person can't refuse! If I write 6 items a day I may have marginal chance of catching Dirk. FWIW, I consider big fishes people with several 1000 points.
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