Fast Reordering of Data Frame Rows

A fast substitute for dplyr::arrange, based on radixorder(v) and inspired by data.table::setorder(v). It returns a sorted copy of the data frame, unless the data is already sorted in which case no copy is made. In addition, rows can be manually re-ordered. roworderv is a programmers version that takes vectors/variables as input.

Use data.table::setorder(v) to sort a data frame without creating a copy.

Usage

roworder(X, ..., na.last = TRUE, verbose = .op[["verbose"]])

roworderv(X, cols = NULL, neworder = NULL, decreasing = FALSE,
          na.last = TRUE, pos = "front", verbose = .op[["verbose"]])

Arguments

X

a data frame or list of equal-length columns.

...

comma-separated columns of X to sort by e.g. var1, var2. Negatives i.e. -var1, var2 can be used to sort in decreasing order of var1. Internally all expressions are turned into strings and startsWith(expr, "-") is used to detect this, thus it does not negate the actual values (which may as well be strings), and you cannot apply any other functions to columns inside roworder() to induce different sorting behavior.

cols

select columns to sort by using a function, column names, indices or a logical vector. The default NULL sorts by all columns in order of occurrence (from left to right).

na.last

logical. If TRUE, missing values in the sorting columns are placed last; if FALSE, they are placed first; if NA they are removed (argument passed to radixorder).

decreasing

logical. Should the sort order be increasing or decreasing? Can also be a vector of length equal to the number of arguments in cols (argument passed to radixorder).

neworder

an ordering vector, can be < nrow(X). if pos = "front" or pos = "end", a logical vector can also be supplied. This argument overwrites cols.

pos

integer or character. Different arrangement options if !is.null(neworder) && length(neworder) < nrow(X).

Int.	String	Description
1	"front"	move rows in `neworder` to the front (top) of `X` (the default).
2	"end"	move rows in `neworder` to the end (bottom) of `X`.
3	"exchange"	just exchange the order of rows in `neworder`, other rows remain in the same position.
4	"after"	place all further selected rows behind the first selected row.

verbose

logical. 1L (default) prints a message when ordering a grouped or indexed frame, indicating that this is not efficient and encouraging reordering the data prior to the grouping/indexing step. Users can also set verbose = 2L to also toggle a message if x is already sorted, implying that no copy was made and the call to roworder(v) is redundant.

Value

A copy of X with rows reordered. If X is already sorted, X is simply returned.

Note

If you don't require a copy of the data, use data.table::setorder (you can also use it in a piped call as it invisibly returns the data).

roworder(v) has internal facilities to deal with grouped and indexed data. This is however inefficient (since in most cases data could be reordered before grouping/indexing), and therefore issues a message if verbose > 0L.

Examples

head(roworder(airquality, Month, -Ozone))
#>   Ozone Solar.R Wind Temp Month Day
#> 1   115     223  5.7   79     5  30
#> 2    45     252 14.9   81     5  29
#> 3    41     190  7.4   67     5   1
#> 4    37     279  7.4   76     5  31
#> 5    36     118  8.0   72     5   2
#> 6    34     307 12.0   66     5  17
head(roworder(airquality, Month, -Ozone, na.last = NA))  # Removes the missing values in Ozone
#>   Ozone Solar.R Wind Temp Month Day
#> 1   115     223  5.7   79     5  30
#> 2    45     252 14.9   81     5  29
#> 3    41     190  7.4   67     5   1
#> 4    37     279  7.4   76     5  31
#> 5    36     118  8.0   72     5   2
#> 6    34     307 12.0   66     5  17

## Same in standard evaluation
head(roworderv(airquality, c("Month", "Ozone"), decreasing = c(FALSE, TRUE)))
#>   Ozone Solar.R Wind Temp Month Day
#> 1   115     223  5.7   79     5  30
#> 2    45     252 14.9   81     5  29
#> 3    41     190  7.4   67     5   1
#> 4    37     279  7.4   76     5  31
#> 5    36     118  8.0   72     5   2
#> 6    34     307 12.0   66     5  17
head(roworderv(airquality, c("Month", "Ozone"), decreasing = c(FALSE, TRUE), na.last = NA))
#>   Ozone Solar.R Wind Temp Month Day
#> 1   115     223  5.7   79     5  30
#> 2    45     252 14.9   81     5  29
#> 3    41     190  7.4   67     5   1
#> 4    37     279  7.4   76     5  31
#> 5    36     118  8.0   72     5   2
#> 6    34     307 12.0   66     5  17

## Custom reordering
head(roworderv(mtcars, neworder = 3:4))               # Bring rows 3 and 4 to the front
#>                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
#> Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
#> Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
#> Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
#> Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1
head(roworderv(mtcars, neworder = 3:4, pos = "end"))  # Bring them to the end
#>                    mpg cyl  disp  hp drat    wt  qsec vs am gear carb
#> Mazda RX4         21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
#> Mazda RX4 Wag     21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
#> Hornet Sportabout 18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
#> Valiant           18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
#> Duster 360        14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
#> Merc 240D         24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
head(roworderv(mtcars, neworder = mtcars$vs == 1))    # Bring rows with vs == 1 to the top
#>                 mpg cyl  disp  hp drat    wt  qsec vs am gear carb
#> Datsun 710     22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive 21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
#> Valiant        18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    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
#> Merc 280       19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4

Usage

Arguments

Value

Note

See also

Examples