[R] Is there an easier way to iterate over multiple data frames in R?

[Jeff Newmiller]

Whenever similar objects are to be handled with similar code, having the data frames stored in lists or even as one big data frame is preferred. If you can load them as such, half the complexity is addressed right there.
The for loop processing is usually wrapped up using base apply functions or "plyr" package functions. Those  idioms are not necessarily faster than for loops, but they can wrap up some common split and assemble steps cleanly.
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Sent from my phone. Please excuse my brevity.

Kaiyin Zhong <kindlychung at gmail.com> wrote:

>> for (d in paste('df', 1:3, sep='')) {
>+  assign(d, as.data.frame(replicate(3, rnorm(4))))
>+ }
>> dats = list(df1,df2,df3)
>> for (i in 1:length(dats)) {
>+  names(dats[[i]]) = c('w', 'l', 'h')
>+ }
>> dats
>[[1]]
>            w           l           h
>1  1.24319239 -0.05543649  0.05409178
>2  0.05124331 -1.89346950  0.33896273
>3 -1.69686777 -0.35963008 -0.91720034
>4  1.30786112 -0.23953238  0.94139356
>
>[[2]]
>          w           l          h
>1 -1.238519 -0.12352187 -1.2577607
>2  1.180469  2.38836107  2.9139199
>3  1.494369 -0.07088712  0.2372746
>4  1.942535  1.47911615  1.1431675
>
>[[3]]
>           w          l          h
>1  1.0198692 -1.4222194  1.9486072
>2  0.3057461  1.7630326 -0.6501801
>3 -0.5576854 -1.1637263 -0.1782680
>4  0.6625268  0.6913202  0.9588915
>> i = 1
>> for (n in paste('df', 1:3, sep='')) {
>+  assign(n, dats[[i]])
>+  i = i+1
>+ }
>> df1
>            w           l           h
>1  1.24319239 -0.05543649  0.05409178
>2  0.05124331 -1.89346950  0.33896273
>3 -1.69686777 -0.35963008 -0.91720034
>4  1.30786112 -0.23953238  0.94139356
>
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>
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