rownames: Convert row names back and forth between columns

In DBI: R Database Interface

Description

These functions provide a reasonably automatic way of preserving the row names of data frame during back-and-forth translation to an SQL table. By default, row names will be converted to an explicit column called "row_names", and any query returning a column called "row_names" will have those automatically set as row names. These methods are mostly useful for backend implementers.

Usage

sqlRownamesToColumn(df, row.names = NA)

sqlColumnToRownames(df, row.names = NA)

Arguments

df	A data frame
row.names	Either TRUE, FALSE, NA or a string. If TRUE, always translate row names to a column called "row_names". If FALSE, never translate row names. If NA, translate rownames only if they're a character vector. A string is equivalent to TRUE, but allows you to override the default name. For backward compatibility, NULL is equivalent to FALSE.

Examples

# If have row names
sqlRownamesToColumn(head(mtcars))
sqlRownamesToColumn(head(mtcars), FALSE)
sqlRownamesToColumn(head(mtcars), "ROWNAMES")

# If don't have
sqlRownamesToColumn(head(iris))
sqlRownamesToColumn(head(iris), TRUE)
sqlRownamesToColumn(head(iris), "ROWNAMES")

Example output

          row_names  mpg cyl disp  hp drat    wt  qsec vs am gear carb
1         Mazda RX4 21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
2     Mazda RX4 Wag 21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
3        Datsun 710 22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
4    Hornet 4 Drive 21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
5 Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
6           Valiant 18.1   6  225 105 2.76 3.460 20.22  1  0    3    1
   mpg cyl disp  hp drat    wt  qsec vs am gear carb
1 21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
2 21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
3 22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
4 21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
5 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
6 18.1   6  225 105 2.76 3.460 20.22  1  0    3    1
           ROWNAMES  mpg cyl disp  hp drat    wt  qsec vs am gear carb
1         Mazda RX4 21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
2     Mazda RX4 Wag 21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
3        Datsun 710 22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
4    Hornet 4 Drive 21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
5 Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
6           Valiant 18.1   6  225 105 2.76 3.460 20.22  1  0    3    1
  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.1         3.5          1.4         0.2  setosa
2          4.9         3.0          1.4         0.2  setosa
3          4.7         3.2          1.3         0.2  setosa
4          4.6         3.1          1.5         0.2  setosa
5          5.0         3.6          1.4         0.2  setosa
6          5.4         3.9          1.7         0.4  setosa
  row_names Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1         1          5.1         3.5          1.4         0.2  setosa
2         2          4.9         3.0          1.4         0.2  setosa
3         3          4.7         3.2          1.3         0.2  setosa
4         4          4.6         3.1          1.5         0.2  setosa
5         5          5.0         3.6          1.4         0.2  setosa
6         6          5.4         3.9          1.7         0.4  setosa
  ROWNAMES Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1        1          5.1         3.5          1.4         0.2  setosa
2        2          4.9         3.0          1.4         0.2  setosa
3        3          4.7         3.2          1.3         0.2  setosa
4        4          4.6         3.1          1.5         0.2  setosa
5        5          5.0         3.6          1.4         0.2  setosa
6        6          5.4         3.9          1.7         0.4  setosa

DBI documentation built on Dec. 20, 2021, 9:07 a.m.