In paulponcet/tribe: Play with the Tribe of Attributes

knitr::opts_chunk$set(collapse = TRUE, comment = "#>")
library(dplyr)
library(tribe)
print.list <- function(x, ...) str(x)

Verbs for easy manipulation of attributes

The tribe package provides verbs for easy manipulation of attributes. These verbs are:

• at_mutate to create or modify attributes;
• at_select to select attributes (and NULLify the others);
• at_rename to rename attributes;
• at_slice to extract attributes.

The function tribe is a convenient synonym of attributes, with the slight difference that it always returns a named list.

df <- data.frame(x = 1:2, y = 2:3) %>%
  at_mutate(example="yes", package="dplyr")
tribe(df)

Use at_slice to extract attribute values:

at_slice(df, names)

Each verb has its standard evaluation version; for instance at_slice_ is the standard evaluation version of at_slice:

at_slice_(df, "class")
at_slice_(df, ~ package)

Similarly at_mutate_ is the standard evaluation version of at_mutate:

df <- df %>%
  at_mutate_(package = ~ NULL, # deletes the attribute called 'package'
             example = ~ "no")
tribe(df)

A new pipe that preserves attributes

The tribe package builds on the magrittr package and brings a new pipe %@>% similar to the pipe %>% that enables propagation of attributes.

df <- data.frame(x = 1:2, y = 2:3) %>%
 at_mutate(example="yes",
           package="tribe", 
           class = c("my_tbl", "data.frame"))

Attributes just created are often lost when the object passes through dplyr verbs, for instance:

tribe(df %>% mutate(z=3))

With the new pipe %@>%, most attributes propagate:

tribe(df %@>% mutate(z=3))

Behind the scene, the shield function operates:

# Attributes are lost when the object passes through dplyr verbs
df2 <- df %>% mutate(z = 3)
tribe(df2)

# Most attributes are kept
df3 <- shield(df2, tribe(df), propagate = "most")
tribe(df3)

# To keep the class, use 'keep_also'
df4 <- shield(df2, tribe(df), propagate = "most", keep_also = "class")
tribe(df4)

One can create a new pipe to adjust attributes propagation settings:

"%newpipe>%" <- make_pipe(propagate="none", keep_also = "example")
tribe(df %newpipe>% mutate(z=3))

paulponcet/tribe documentation built on Nov. 24, 2019, 10:08 p.m.