Subset an object based on logical criteria

These methods can be used to subset objects based on a logical vector.

Usage

keep_bool(x, bool, invert = FALSE, ...)

drop_bool(x, bool, ...)

# S3 method for fnames
drop_bool(x, bool, ...)

# S3 method for fnames
keep_bool(x, bool, invert = FALSE, ...)

# S3 method for freqlist
drop_bool(x, bool, ...)

# S3 method for freqlist
keep_bool(x, bool, invert = FALSE, ...)

# S3 method for tokens
drop_bool(x, bool, ...)

# S3 method for tokens
keep_bool(x, bool, invert = FALSE, ...)

# S3 method for types
drop_bool(x, bool, ...)

# S3 method for types
keep_bool(x, bool, invert = FALSE, ...)

Arguments

x

An object of any of the classes for which the method is implemented.

bool

A logical vector of the same length as x. If bool is not of the correct length, it is recycled. Assuming invert is FALSE, those items are selected for which bool is TRUE.

invert

Logical. Whether the matches should be selected rather than the non-matches.

...

Additional arguments.

Value

Object of the same class as x with the selected elements only.

Details

The methods keep_pos() and drop_pos() are part of a family of methods of the mclm package used to subset different objects. The methods starting with keep_ extract the items in x based on the criterion specified by the second argument. In contrast, the methods starting with drop_ exclude the items that match the criterion in the same argument.

Calling a drop_ method is equivalent to calling its keep_ counterpart when the invert argument is TRUE.

See also

Other subsetters: brackets, keep_pos(), keep_re(), keep_types()

Examples

# For a 'freqlist' object---------------------
(flist <- freqlist("The man and the mouse.", as_text = TRUE))
#> Frequency list (types in list: 4, tokens in list: 5)
#> rank  type abs_freq nrm_freq
#> ---- ----- -------- --------
#>    1   the        2     4000
#>    2   and        1     2000
#>    3   man        1     2000
#>    4 mouse        1     2000

keep_bool(flist, type_freqs(flist) < 2)
#> Frequency list (types in list: 3, tokens in list: 3)
#> <total number of tokens: 5>
#> rank orig_rank  type abs_freq nrm_freq
#> ---- --------- ----- -------- --------
#>    1         2   and        1     2000
#>    2         3   man        1     2000
#>    3         4 mouse        1     2000
drop_bool(flist, type_freqs(flist) >= 2)
#> Frequency list (types in list: 3, tokens in list: 3)
#> <total number of tokens: 5>
#> rank orig_rank  type abs_freq nrm_freq
#> ---- --------- ----- -------- --------
#>    1         2   and        1     2000
#>    2         3   man        1     2000
#>    3         4 mouse        1     2000
keep_bool(flist, ranks(flist) <= 3)
#> Frequency list (types in list: 3, tokens in list: 4)
#> <total number of tokens: 5>
#> rank orig_rank type abs_freq nrm_freq
#> ---- --------- ---- -------- --------
#>    1         1  the        2     4000
#>    2         2  and        1     2000
#>    3         3  man        1     2000

keep_bool(flist, c(FALSE, TRUE, TRUE, FALSE)) 
#> Frequency list (types in list: 2, tokens in list: 2)
#> <total number of tokens: 5>
#> rank orig_rank type abs_freq nrm_freq
#> ---- --------- ---- -------- --------
#>    1         2  and        1     2000
#>    2         3  man        1     2000

(flist2 <- keep_bool(flist, type_freqs(flist) < 2))
#> Frequency list (types in list: 3, tokens in list: 3)
#> <total number of tokens: 5>
#> rank orig_rank  type abs_freq nrm_freq
#> ---- --------- ----- -------- --------
#>    1         2   and        1     2000
#>    2         3   man        1     2000
#>    3         4 mouse        1     2000
keep_bool(flist2, orig_ranks(flist2) > 2)
#> Frequency list (types in list: 2, tokens in list: 2)
#> <total number of tokens: 5>
#> rank orig_rank  type abs_freq nrm_freq
#> ---- --------- ----- -------- --------
#>    1         3   man        1     2000
#>    2         4 mouse        1     2000

# For a 'types' object ----------------------
(tps <- as_types(letters[1:10]))
#> Type collection of length 10
#>    type
#>    ----
#>  1    a
#>  2    b
#>  3    c
#>  4    d
#>  5    e
#>  6    f
#>  7    g
#>  8    h
#>  9    i
#> 10    j

keep_bool(tps, c(TRUE, FALSE))
#> Type collection of length 5
#>   type
#>   ----
#> 1    a
#> 2    c
#> 3    e
#> 4    g
#> 5    i
drop_bool(tps, c(TRUE, FALSE))
#> Type collection of length 5
#>   type
#>   ----
#> 1    b
#> 2    d
#> 3    f
#> 4    h
#> 5    j

# For a 'tokens' object ----------------------
(tks <- as_tokens(letters[1:10]))
#> Token sequence of length 10
#> idx token
#> --- -----
#>   1     a
#>   2     b
#>   3     c
#>   4     d
#>   5     e
#>   6     f
#>   7     g
#>   8     h
#>   9     i
#>  10     j

keep_bool(tks, c(TRUE, FALSE))
#> Token sequence of length 5
#> idx token
#> --- -----
#>   1     a
#>   2     c
#>   3     e
#>   4     g
#>   5     i
drop_bool(tks, c(TRUE, FALSE))
#> Token sequence of length 5
#> idx token
#> --- -----
#>   1     b
#>   2     d
#>   3     f
#>   4     h
#>   5     j