The R package seplyr supplies improved standard evaluation interfaces for some common data data plying tasks.
To install this packing in R please either install from CRAN with:
install.packages('seplyr')or from GitHub:
devtools::install_github('WinVector/seplyr')In dplyr if you know the names of columns when you are writing code you can write code such as the following.
## [1] '1.0.5'## mpg cyl disp hp drat wt qsec vs am gear carb
## Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
## Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
## Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
## Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
## Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
## Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1In dplyr 0.7.* if the names of the columns are coming from a variable set elsewhere you would to need to use a tool to substitute those names in. One such tool is rlang/tidyeval (though we strongly prefer seplyr and wrapr::let())). rlang/tidyeval works as follows (for comparison only, this is not our suggested workflow).
# Assume this is set elsewhere,
# supplied by a user, function argument, or control file.
orderTerms <- c('cyl', 'desc(gear)')
# Now convert into splice-able types, the idea is the user
# supplies variable names that we later convert to "quosures"
# for use in `dplyr` 0.7.* generic code.
# This code is near the pipe under the rule:
# "If you are close enough to form a quosure,
# you are close enough to re-code the analysis"
orderQs <- lapply(orderTerms,
function(si) { rlang::parse_expr(si) })
# pipe
datasets::mtcars %>%
arrange(!!!orderQs) %>%
head()## mpg cyl disp hp drat wt qsec vs am gear carb
## Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
## Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
## Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
## Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
## Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
## Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1If you don’t want to try and digest entire theory of quasi-quoting and splicing (the !!! operator) then you can use seplyr which conveniently and legibly wraps the operations as follows:
## Loading required package: wrapr##
## Attaching package: 'wrapr'## The following object is masked from 'package:dplyr':
##
## coalesce
datasets::mtcars %.>%
arrange_se(., orderTerms) %>%
head(.)## mpg cyl disp hp drat wt qsec vs am gear carb
## Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
## Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
## Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
## Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
## Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
## Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1The idea is: the above code looks very much like simple dplyr code used running an analysis, and yet is very easy to parameterize and re-use in a script or package.
seplyr::arrange_se() performs the wrapping for you without you having to work through the details of rlang. If you are interested in the details seplyr itself is a good tutorial. For example you can examine seplyr’s implementation to see the necessary notations (using a command such as print(arrange_se)). And, of course, we try to supply some usable help entries, such as: help(arrange_se). Some more discussion of the ideas can be found here.
The current set of SE adapters includes (all commands of the form NAME_se() being adapters for a dplyr::NAME() method):
add_count_se()add_tally_se()arrange_se()count_se()distinct_se()filter_se()group_by_se()group_indices_se()mutate_se()rename_se()select_se()summarize_se()tally_se()transmute_se()Only two of the above are completely redundant. seplyr::group_by_se() essentially works as dplyr::group_by_at() and seplyr::select_se() essentially works as dplyr::select_at(). The others either have different semantics or currently (as of dplyr 0.7.1) no matching dplyr::*_at() method. Roughly all seplyr is trying to do is give a uniform first-class standard interface to all of the primary deprecated underscore suffixed verbs (such as dplyr::arrange_).
We also have a few methods that work around a few of the minor inconvenience of working with variable names as strings:
deselect()rename_mp()Here is a example using seplyr::summarize_se().
datasets::iris %.>%
group_by_se(., "Species") %.>%
summarize_se(., c("Mean.Sepal.Length" := "mean(Sepal.Length)",
"Mean.Sepal.Width" := "mean(Sepal.Width)"))## # A tibble: 3 x 3
## Species Mean.Sepal.Length Mean.Sepal.Width
## <fct> <dbl> <dbl>
## 1 setosa 5.01 3.43
## 2 versicolor 5.94 2.77
## 3 virginica 6.59 2.97In addition to the series of adapters we also supply a number of useful new verbs including:
group_summarize() Binds grouping, arrangement, and summarization together for clear documentation of intent.add_group_summaries() Adds per-group summaries to data.add_group_indices() Adds a column of per-group ids to data.add_group_sub_indices() Adds a column of in-group rank ids to data.add_rank_indices() Adds rank indices to data.partition_mutate_se(): vignette, and article.if_else_device(): article.seplyr is designed to be a thin package that passes work to dplyr. If you want a package that works around dplyr implementation differences on different data sources I suggest trying our own replyr package. Another alternative is using wrapr::let().
seplyr methods are short and have examples in their help, so always try both help and printing the method (for example: help(select_se) and print(select_se)). Printing methods can show you how to use dplyr directly with rlang/tidyeval methodology (allowing you to skip seplyr).
Some inspiration comes from Sebastian Kranz’s s_dplyr. Please see help("%.>%", package="wrapr") for details on “dot pipe.”