I want to generate a character vector with 20 elements, each has a random string.
So I generate a random string with the following code:
sample(x = c(letters, LETTERS), size = sample.int(100, 1), replace = T) %>% paste0(collapse = "")
and I generate the vector with this:
replicate(n = 20, expr = sample(x = c(letters, LETTERS), size = sample.int(100, 1), replace = T) %>% paste0(collapse = ""))
(I am basically putting the first code chunk in replicate as an argument.)
and the output is the following (which is exactly what I want):
[1] "DyHpcnruLfKHOsvy"
[2] "lQqwOkKD"
[3] "XddKDCtOJqZHxAgHqreDwWSBQkDCBdwFclHMFhuCzXXwb"
[4] "bmuiUUdsnHJsxIEyeLClvbLGBbfEgXFVsScrWxiTcZxPNTTwAJGZDVgJzDKUG"
[5] "yBDZYKxPXXGFwmlPWNMQuUJsfRXsBoQhuVXnYfMNkHFpmAgSRafGBzkKu"
[6] "LLuNdUoayRwtLqRJKrnxERpMmlntghfkjUqPkxMMubUozsLbPOFESOqtAWKoojOrttVCQlIYkyGRglr"
[7] "KuydhJOVZNNDrrMLDeWda"
[8] "ItwNtPGIQDsqCRBoVUCkClgHzCUiYRAiHIQRqpGBpfzRXgmWFArRtmnWhtciPgLlqrVs"
[9] "BqqEjCpUHLzOlsmqiAOchAKysbtUCzce"
[10] "JJzdyoFqFnZOeLAABK"
[11] "bakCawEaOkMspowlFUsAMjAbMxNxguHAHLomiGtenMuENNuPElGwqdqNdVS"
[12] "OEtuDejCDVfDwGjKbjWSCsicrRmqGGpWyqMfaGGPNkJhJMbgUtkjbcwitLqVojCERLxTWaCNFRltxgiwdJAbUtoksW"
[13] "crVVVzIyWbAlfyFndgipAZZJLcMqtEtZtBpbisbyAUWsKTJLiwyNvyVPPuoxOkafEeLARYDEOqEoh"
[14] "QgAZkacEMBbGebUCToXFTLSqqlYhqpbdsPYvIrwJhfpgDcPiJlfiATEEDrYahyXgxLEVXvsbQ"
[15] "jHSYxhskNMxYnnbGQLQgTJKsuRXEeDpiPlonDABrXxivwepNNvZGrugSfHoMi"
[16] "CdCDpUjlUyLwiujvcLcxpNZjtxUMTMVYxnjCEQqbJQOXZJeTLHXQRbHaIsOIDmKeyNainhphvwEAHscCAhOjUsqQe"
[17] "XvoelRDEYrxMfffBjRzmFPrLRjayCLRFVpWxzjcIxkRZQiPutModt"
[18] "FNjvlFdyrRTVDWvnXVWjckCDFUkxnbUfkqYDNIPZVMOfjUejEKiuhhTXdi"
[19] "qsQDQtaVyoNVHtNNltPqLEuNGDxiscsOsXZfhaUNdBCoSwcouhhpwFhfCcqYPPFXrnjKqnlEknuKsaWVizaIacMiT"
[20] "ykGqCILONPhzEABAuNjtEjzXxeFLnybwZdVEbDdzDQoDKmIiLvZNhoEEEvYJS"
But here is the problem. When I try to pipe the first code chuck into replicate using magrittr's pipe (%>%), I get an output with similar strings!
This is how I do it:
sample(x = c(letters, LETTERS), size = sample.int(100, 1), replace = T) %>% paste0(collapse = "") %>% replicate(n = 20, expr = ., simplify = "array")
also, I tried to wrap them into parentheses:
(sample(x = c(letters, LETTERS), size = sample.int(100, 1), replace = T) %>% paste0(collapse = "")) %>% replicate(n = 20, expr = ., simplify = "array")
But, in both cases, this is the undesirable output:
[1] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[2] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[3] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[4] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[5] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[6] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[7] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[8] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[9] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[10] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[11] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[12] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[13] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[14] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[15] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[16] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[17] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[18] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[19] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
[20] "yNLJofKIlodQuFVzseeYOmjcxJRxFzgSXWCFoBhCFyJplcgVrrIEhoSSDJXHWhlkWkDHdtKexZFEvIHFokUNg"
What do you think the problem is here?
Both calls differ in number of operations. Essentially, magrittr's %>% simply passes the result of one operation into another operation.
In first call, only one operation is run where replicate runs its defined expression here being random sample + paste0 20 times. In other words, replicate directly runs sample 20 times.
replicate(
n = 20,
expr = sample(
x = c(letters, LETTERS), size = sample.int(100, 1), replace = T
) %>% paste0(collapse = "")
)
In second call, there are two operations where a random sample is run once and then its result is passed into replicate that simply repeats (i.e., replicates) this expression 20 times. Specifically, replicate never directly runs sample.
sample(
x = c(letters, LETTERS),
size = sample.int(100, 1),
replace = T
) %>% replicate(n = 20, expr = ., simplify = "array")
Interestingly, this above behavior differs from base R's new pipe |> introduced in 4.1.0 and its RHS placeholder _ in 4.2.0:
sample(
x = c(letters, LETTERS),
size = sample.int(100, 1),
replace = T
) |> replicate(n = 20, expr = _, simplify = "array")
where per deparse(substitute(...)) as shown by @Dirk is a handy re-write of nested calls which resembles your first call:
deparse(
substitute(
sample(x = c(letters, LETTERS), size = sample.int(100, 1), replace = T) |>
replicate(n = 20, expr = _, simplify = "array")
)
)
[1] "replicate(n = 20, expr = sample(x = c(letters, LETTERS), size = sample.int(100, "
[2] " 1), replace = T), simplify = \"array\")"