CODEWITHSUNDEEP
rlistdataframelapplysample
antecessor
antecessor

Reputation: 2800

Sample a list of dataframes in R

I have a list composed of 16 dataframes (dientes). I would like to sample 80% of the rows with no replacement in each dataframe. I tried with these lapply() functions with no success:

index <- lapply(1:nrow(dientes), sample, round(0.8*nrow), replace = F)
index <- lapply(dientes, sample, round(0.8*nrow), replace = F)

Where am I wrong?

Upvotes: 0

Views: 185

Answers (2)

Chris
Chris

Reputation: 310

I would do the following:

index <- lapply(dientes, function(x){x[sample(x, round(0.8*nrow(x)), replace = F),]})

lapply takes the list dientes as input

function(x){..} applies the operation you want to each element

x is each element and you take rows from it with x[sample(...),]

Upvotes: 1

user12728748
user12728748

Reputation: 8506

If index should contain the list of sampled data.frames, you could do this:

## mock list of data.frames
dientes <- list(A=mtcars, B=iris, C=volcano)

## count input rows
lapply(dientes, nrow)
#> $A
#> [1] 32
#> 
#> $B
#> [1] 150
#> 
#> $C
#> [1] 87

index <- lapply(dientes, function(x) x[sample(nrow(x), round(0.8*nrow(x))), ])

## count output rows
lapply(index, nrow)
#> $A
#> [1] 26
#> 
#> $B
#> [1] 120
#> 
#> $C
#> [1] 70

Created on 2020-03-18 by the reprex package (v0.3.0)

Upvotes: 2

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