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keyholder

keyholder is a package for storing information (keys) about rows of data frame like objects. The common use cases are to track rows of data without modifying it and to backup and restore information about rows. This is done with creating a class keyed_df which has special attribute "keys". Keys are updated according to changes in rows of reference data frame.

keyholder is designed to work tightly with dplyr package. All its one- and two-table verbs update keys properly.

Installation

You can install keyholder from github with:

# install.packages("devtools")
devtools::install_github("echasnovski/keyholder")

Usage

keyholder provides a set of functions to work with keys:

  • Set keys with assign_keys() and key_by().
  • Get all keys with keys(). Get one specific key with pull_key().
  • Restore information stored in certain keys with restore_keys() and its scoped variants (*_all(), *_if() and *_at()).
  • Rename certain keys with rename_keys() and its scoped variants.
  • Remove certain keys with remove_keys() and its scoped variants. Completely unkey object with unkey().
  • Track rows with use_id() and special .id key.

For more detailed explanations and examples see package vignettes and documentation.

Common use cases

library(dplyr)
library(keyholder)
mtcars_tbl <- mtcars %>% as_tibble()
  • Track rows without modifying data:
mtcars_tbl_id <- mtcars_tbl %>%
  # Creates a key '.id' with row index
  use_id() %>%
  filter(vs == 1, gear == 4)

mtcars_tbl_id
#> # A keyed object. Keys: .id 
#> # A tibble: 10 x 11
#>     mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1  22.8     4 108.0    93  3.85  2.32 18.61     1     1     4     1
#> 2  24.4     4 146.7    62  3.69  3.19 20.00     1     0     4     2
#> 3  22.8     4 140.8    95  3.92  3.15 22.90     1     0     4     2
#> # ... with 7 more rows

mtcars_tbl_id %>% pull_key(.id)
#>  [1]  3  8  9 10 11 18 19 20 26 32
  • Backup and restore information:
mtcars_tbl_keyed <- mtcars_tbl %>%
  # Backup
  key_by(vs, am, gear) %>%
  # Modify
  mutate(vs = am) %>%
  group_by(vs) %>%
  mutate(gear = max(gear))

# Restore with recomputing groups
mtcars_tbl_keyed %>%
  restore_keys_all() %>%
  all.equal(mtcars_tbl)
#> [1] TRUE

# Restore with renaming
mtcars_tbl_keyed %>%
  restore_keys_at("vs", .funs = funs(paste0(., "_old")))
#> # A keyed object. Keys: vs, am, gear 
#> # A tibble: 32 x 12
#> # Groups:   vs [2]
#>     mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb vs_old
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>  <dbl>
#> 1  21.0     6   160   110  3.90 2.620 16.46     1     1     5     4      0
#> 2  21.0     6   160   110  3.90 2.875 17.02     1     1     5     4      0
#> 3  22.8     4   108    93  3.85 2.320 18.61     1     1     5     1      1
#> # ... with 29 more rows
  • As a special case of previous usage one can also hide columns for convenient use of dplyr's *_if scoped variants of verbs:
# Restored key goes to the end of the tibble
mtcars_tbl %>%
  key_by(mpg, .exclude = TRUE) %>%
  mutate_if(is.numeric, round, digits = 0) %>%
  restore_keys_all()
#> # A keyed object. Keys: mpg 
#> # A tibble: 32 x 11
#>     cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb   mpg
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1     6   160   110     4     3    16     0     1     4     4  21.0
#> 2     6   160   110     4     3    17     0     1     4     4  21.0
#> 3     4   108    93     4     2    19     1     1     4     1  22.8
#> # ... with 29 more rows

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