  id =  sample(1e5, 1e6, TRUE),                      \n         v =  sample(5, 1e6, TRUE)                        \n    )\ndf1 &lt;- df %&gt;% group_by(id)\nsystem.time(summarize(df1,  mean(v)))\n# user  system elapsed \n#  0.041   0.001   0.056 \nsystem.time(summarize(df1,  quantile(v, 0.50, type = 1)))\n#   user  system elapsed \n#15.080   0.060  15.157 \n```\n\nSince quantile has so many options, maybe a function called `qtile` which implements only one kind (the kind used for `ntile`).\n</span>
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