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hyginn 2021-10-05 23:48:34 +02:00
parent ce78612a3b
commit c9b939b096
1 changed files with 9 additions and 9 deletions
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18
RPR-Pipe.R
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@ -50,19 +50,19 @@
# On the unix command line, pipes were used from the very beginning, implemented # On the unix command line, pipes were used from the very beginning, implemented
# with the "|" pipe character. # with the "|" pipe character.
# #
# In R, the magrittr package provided the %>% operator, and recently the %|>% # In R, the magrittr package provided the %>% operator, and recently the |>
# operator has been introduced into base R. # operator has been introduced into base R.
# #
# However there are alternatives: intermediate assignment, and nested functions # However there are alternatives: intermediate assignment, and nested functions
# that have always existed in bas R anyway. # that have always existed in base R anyway.
# #
# Let us look at an example. In writing this, I found out that virtually # Let us look at an example. In writing this, I found out that virtually
# ALL non-trivial examples I cvame up with don't translate well into this idiom # ALL non-trivial examples I came up with don't translate well into this idiom
# at all. It is actually quite limited to simple filtering operations on # at all. It is actually quite limited to simple filtering operations on
# data. A more intersting example might be added in the future, let me know if # data. A more interesting example might be added in the future, let me know if
# you have a good idea. # you have a good idea.
# #
# A somwhat contrived example is to soart a list of files by the # A somewhat contrived example is to sort a list of files by the
# length of the file names: # length of the file names:
myFiles <- list.files(pattern = "\\.R$") myFiles <- list.files(pattern = "\\.R$")
@ -88,7 +88,7 @@ if (! requireNamespace("magrittr", quietly = TRUE)) {
library(magrittr) library(magrittr)
nchar(myFiles) %>% order %>% myFiles[.] myFiles %>% nchar %>% order %>% myFiles[.]
# = 4 Base R Pipe ========================================================= # = 4 Base R Pipe =========================================================
@ -97,12 +97,12 @@ nchar(myFiles) %>% order %>% myFiles[.]
# into the language is very rare. # into the language is very rare.
# #
# Unfortunately it won't (yet) work with the '[' function, so we need to write # Unfortunately it won't (yet) work with the '[' function, so we need to write
# an intermediate fucntion for this example # an intermediate function for this example
extract <- function(x, v) { extract <- function(x, v) {
return(v[x]) return(v[x])
} }
nchar(myFiles) |> order() |> extract(myFiles) myFiles |> nchar() |> order() |> extract(myFiles)
# = 5 Intermediate Assignment ============================================= # = 5 Intermediate Assignment =============================================
@ -114,7 +114,7 @@ nchar(myFiles) |> order() |> extract(myFiles)
# replacing it with the pipe makes things much better. My preferred idiom is # replacing it with the pipe makes things much better. My preferred idiom is
# to use intermediate assignments. Only then is it convenient to examine # to use intermediate assignments. Only then is it convenient to examine
# the code step by step and validate every single step. And that is the most # the code step by step and validate every single step. And that is the most
# important objective at all: no code is good if it doe not compute # important objective at all: no code is good if it does not compute
# correctly. # correctly.