Make a number of dataframes by using loop

Question

I have data frame "df" following:

df=data.frame(time=as.factor(rep(c(0.01*(1:100)),each=49)),
          roi=rep(1:49,100),
          area=runif(4900, 5.0, 7.5),hours=(rep(1:10,each=490)))

The df is split into 10 smaller data frames based on column "hours"

x=split(df,df$hours)

In each sub-data frame one new data frame "br[i] is made following:

br1=data.frame(x$`1`[c(1,round(nrow(x$`1`)*(1:4)/4)),])
br1$Min=c(0,15,30,45,60)
br2=data.frame(x$`2`[c(1,round(nrow(x$`2`)*(1:4)/4)),])
br2$Min=c(0,15,30,45,60)
...
br10=data.frame(x$`10`[c(1,round(nrow(x$`10`)*(1:4)/4)),])
br10$Min=c(0,15,30,45,60)

The question is how to made 10 data frames "br" automatically without repeat such above commands in many time?

Thanks so much for any response!

perhaps lapply(x, function(x) x[c(1,round(nrow(x)*(1:4)/4)),]) — mtoto
– mtoto, Commented Aug 8, 2016 at 13:00

Abdou · Accepted Answer · 2016-08-08 13:03:39Z

4

Try:

lapply(split(df,df$hours), function(x) {
    br=data.frame(x[c(1,round(nrow(x)*(1:4)/4)),])
    br$Min=c(0,15,30,45,60)
    return(br)
})

answered Aug 8, 2016 at 13:03

Abdou

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1 Comment

Hoang Le Over a year ago

@ Abdou: Thank you so much!

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