OREdplyr functions for selecting and ordering data in columns and rows of an ore.frame object.
Table 3-2 Selecting and Ordering Columns and Rows
| Function | Description |
|---|---|
|
|
Orders rows by the specified columns. |
|
|
Sorts an |
|
|
Selects unique rows from an input |
|
|
Filters rows by matching the specified condition. |
|
|
Adds new columns. |
|
|
Renames the specified columns and keeps all columns. |
|
|
Selects only the specified columns. |
|
|
Selects rows by position; ignores the grouping of the input ordered |
|
|
Adds new columns and drops the existing columns. |
Examples of the select and rename functions of the OREdplyr package.
Example 3-65 Selecting Columns
The following examples select columns from the IRIS ore.frame object that is created by using the ore.push function on the iris data.frame objects.
IRIS <- ore.push(iris) # Select the specified column names(select(IRIS, Petal.Length)) names(select(IRIS, petal_length = Petal.Length)) # Drop the specified column names(select(IRIS, -Petal.Length)) # rename() keeps all variables names(rename(IRIS, petal_length = Petal.Length))
Listing for This Example
R> IRIS <- ore.push(iris) R> # Select the specified column R> names(select(IRIS, Petal.Length)) [1] "Petal.Length" R> names(select(IRIS, petal_length = Petal.Length)) [1] "petal_length" R> R> # Drop the specified column R> names(select(IRIS, -Petal.Length)) [1] "Sepal.Length" "Sepal.Width" "Petal.Width" "Species" R> R> # rename() keeps all variables R> names(rename(IRIS, petal_length = Petal.Length)) [1] "Sepal.Length" "Sepal.Width" "petal_length" "Petal.Width" "Species"
Examples of the select_ function of the OREdplyr package.
Example 3-66 Programming with select
This example uses the select_ function to select columns from the IRIS ore.frame object that is created by using the ore.push function on the iris data.frame object.
IRIS <- ore.push(iris) # Use ~, double quote, or quote function to specify the column to select head(select_(IRIS, ~Petal.Length)) head(select_(IRIS, "Petal.Length")) head(select_(IRIS, quote(-Petal.Length), quote(-Petal.Width))) head(select_(IRIS, .dots = list(quote(-Petal.Length), quote(-Petal.Width))))
Listing for This Example
R> IRIS <- ore.push(iris) R> # Use ~, double quote, or quote function to specify the column to select R> head(select_(IRIS, ~Petal.Length)) Petal.Length 1 1.4 2 1.4 3 1.3 4 1.5 5 1.4 6 1.7 R> head(select_(IRIS, "Petal.Length")) Petal.Length 1 1.4 2 1.4 3 1.3 4 1.5 5 1.4 6 1.7 R> head(select_(IRIS, quote(-Petal.Length), quote(-Petal.Width))) Sepal.Length Sepal.Width Species 1 5.1 3.5 setosa 2 4.9 3.0 setosa 3 4.7 3.2 setosa 4 4.6 3.1 setosa 5 5.0 3.6 setosa 6 5.4 3.9 setosa R> head(select_(IRIS, .dots = list(quote(-Petal.Length), quote(-Petal.Width)))) Sepal.Length Sepal.Width Species 1 5.1 3.5 setosa 2 4.9 3.0 setosa 3 4.7 3.2 setosa 4 4.6 3.1 setosa 5 5.0 3.6 setosa 6 5.4 3.9 setosa
Examples of the distinct and arrange functions of the OREdplyr package.
Example 3-67 Selecting Distinct Columns
df <- data.frame( x = sample(10, 100, rep = TRUE), y = sample(10, 100, rep = TRUE) ) DF <- ore.push(df) nrow(DF) nrow(distinct(DF)) arrange(distinct(DF, x), x) arrange(distinct(DF, y), y) # Use distinct on computed variables arrange(distinct(DF, diff = abs(x - y)), diff)
Listing for This Example
R> df <- data.frame(
+ x = sample(10, 100, rep = TRUE),
+ y = sample(10, 100, rep = TRUE)
+ )
R> DF <- ore.push(df)
R> nrow(DF)
[1] 100
R> nrow(distinct(DF))
[1] 66
R> arrange(distinct(DF, x), x)
x
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
R> arrange(distinct(DF, y), y)
y
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
R>
R> # Use distinct on computed variables
R> arrange(distinct(DF, diff = abs(x - y)), diff)
diff
1 0
2 1
3 2
4 3
5 4
6 5
7 6
8 7
9 8
10 9
Examples of the slice and filter functions of the OREdplyr package.
Example 3-68 Selecting Rows by Position
MTCARS <- ore.push(mtcars) # Display the names of the rows in MTCARS rownames(MTCARS) # Select the first row slice(MTCARS, 1L) # Arrange the rows by horsepower, then select the first row by position MTCARS <- arrange(MTCARS, hp) slice(MTCARS, 1L) by_cyl <- group_by(MTCARS, cyl) # Grouping is ignored by slice. slice(by_cyl, 1:2) # Use filter and row_number to obtain slices per group. filter(by_cyl, row_number(hp) < 3L)
Listing for This Example
R> MTCARS <- ore.push(mtcars)
R> # Display the names of the rows in MTCARS
R> rownames(MTCARS)
[1] "Mazda RX4" "Mazda RX4 Wag" "Datsun 710" "Hornet 4 Drive" "Hornet Sportabout"
[6] "Valiant" "Duster 360" "Merc 240D" "Merc 230" "Merc 280"
[11] "Merc 280C" "Merc 450SE" "Merc 450SL" "Merc 450SLC" "Cadillac Fleetwood"
[16] "Lincoln Continental" "Chrysler Imperial" "Fiat 128" "Honda Civic" "Toyota Corolla"
[21] "Toyota Corona" "Dodge Challenger" "AMC Javelin" "Camaro Z28" "Pontiac Firebird"
[26] "Fiat X1-9" "Porsche 914-2" "Lotus Europa" "Ford Pantera L" "Ferrari Dino"
[31] "Maserati Bora" "Volvo 142E"
R> # Select the first row
R> slice(MTCARS, 1L)
mpg cyl disp hp drat wt qsec vs am gear carb
Mazda RX4 21 6 160 110 3.9 2.62 16.46 0 1 4 4
R>
R> # Arrange the rows by horsepower, then select the first row by position
R> MTCARS <- arrange(MTCARS, hp)
R> slice(MTCARS, 1L)
mpg cyl disp hp drat wt qsec vs am gear carb
1 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
R>
R> by_cyl <- group_by(MTCARS, cyl)
R> # Grouping is ignored by slice
R> slice(by_cyl, 1:2)
mpg cyl disp hp drat wt qsec vs am gear carb
1 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
2 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
Warning message:
In slice_.ore.frame(.data, .dots = .ore.dplyr.exprall(..., env = parent.frame())) :
grouping is ignored
R> # Use filter and row_number to obtain slices per group
R> filter(by_cyl, row_number(hp) < 3L)
mpg cyl disp hp drat wt qsec vs am gear carb
1 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
2 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
3 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1
4 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4
5 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2
6 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2
Examples of the arrange and desc functions of the OREdplyr package.
Example 3-69 Arranging Columns
This example arranges columns from the ore.frame object MTCARS that is created by using the ore.push function on the mtcars data.frame object. The second arrange() invocation calls the desc() function to arrange the values in descending order.
MTCARS <- ore.push(mtcars) head(arrange(mtcars, cyl, disp)) head(arrange(MTCARS, desc(disp)))
Listing for This Example
R> MTCARS <- ore.push(mtcars) R> head(arrange(MTCARS, cyl, disp)) mpg cyl disp hp drat wt qsec vs am gear carb 1 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1 2 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 3 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 4 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1 5 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2 6 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 R> head(arrange(MTCARS, desc(disp))) mpg cyl disp hp drat wt qsec vs am gear carb 1 10.4 8 472 205 2.93 5.250 17.98 0 0 3 4 2 10.4 8 460 215 3.00 5.424 17.82 0 0 3 4 3 14.7 8 440 230 3.23 5.345 17.42 0 0 3 4 4 19.2 8 400 175 3.08 3.845 17.05 0 0 3 2 5 18.7 8 360 175 3.15 3.440 17.02 0 0 3 2 6 14.3 8 360 245 3.21 3.570 15.84 0 0 3 4
Examples of the filter function of the OREdplyr package.
Example 3-70 Filtering Columns
This example filters columns from the MTCARS ore.frame object that is created by using the ore.push function on the mtcars data.frame object.
MTCARS <- ore.push(mtcars) head(filter(MTCARS, cyl == 8)) # Using multiple criteria head(filter(MTCARS, cyl < 6 & vs == 1)) # Using multiple arguments is the equivalent to using & head(filter(MTCARS, cyl < 6, vs == 1))
Listing for This Example
R> MTCARS <- ore.push(mtcars) R> head(filter(MTCARS, cyl == 8)) mpg cyl disp hp drat wt qsec vs am gear carb 1 18.7 8 360.0 175 3.15 3.44 17.02 0 0 3 2 2 14.3 8 360.0 245 3.21 3.57 15.84 0 0 3 4 3 16.4 8 275.8 180 3.07 4.07 17.40 0 0 3 3 4 17.3 8 275.8 180 3.07 3.73 17.60 0 0 3 3 5 15.2 8 275.8 180 3.07 3.78 18.00 0 0 3 3 6 10.4 8 472.0 205 2.93 5.25 17.98 0 0 3 4 R> head(filter(MTCARS, cyl < 6 & vs == 1)) mpg cyl disp hp drat wt qsec vs am gear carb 1 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 2 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 3 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 4 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 5 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 6 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1 R> R> # Using multiple arguments is the equivalent to using & R> head(filter(MTCARS, cyl < 6, vs == 1)) mpg cyl disp hp drat wt qsec vs am gear carb 1 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 2 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 3 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 4 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 5 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 6 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
Examples of the mutate and transmute functions of the OREdplyr package.
Example 3-71 Mutating Columns
This example uses the MTCARS ore.frame object that is created by using the ore.push function on the mtcars data.frame object.
The mutate function adds the extra column displ_1 with the value derived from that of column disp. Setting the column to NULL removes the column.
MTCARS <- ore.push(mtcars) head(mutate(MTCARS, displ_l = disp / 61.0237)) head(transmute(MTCARS, displ_l = disp / 61.0237)) head(mutate(MTCARS, cyl = NULL)) head(mutate(MTCARS, cyl = NULL, hp = NULL, displ_l = disp / 61.0237))
Listing for This Example
R> MTCARS <- ore.push(mtcars) R> head(mutate(MTCARS, displ_l = disp / 61.0237)) mpg cyl disp hp drat wt qsec vs am gear carb displ_l 1 21.0 6 160 110 3.90 2.620 16.46 0 1 4 4 2.621932 2 21.0 6 160 110 3.90 2.875 17.02 0 1 4 4 2.621932 3 22.8 4 108 93 3.85 2.320 18.61 1 1 4 1 1.769804 4 21.4 6 258 110 3.08 3.215 19.44 1 0 3 1 4.227866 5 18.7 8 360 175 3.15 3.440 17.02 0 0 3 2 5.899347 6 18.1 6 225 105 2.76 3.460 20.22 1 0 3 1 3.687092 R> head(transmute(MTCARS, displ_l = disp / 61.0237)) displ_l 1 2.621932 2 2.621932 3 1.769804 4 4.227866 5 5.899347 6 3.687092 R> head(mutate(mtcars, cyl = NULL)) mpg disp hp drat wt qsec vs am gear carb 1 21.0 160 110 3.90 2.620 16.46 0 1 4 4 2 21.0 160 110 3.90 2.875 17.02 0 1 4 4 3 22.8 108 93 3.85 2.320 18.61 1 1 4 1 4 21.4 258 110 3.08 3.215 19.44 1 0 3 1 5 18.7 360 175 3.15 3.440 17.02 0 0 3 2 6 18.1 225 105 2.76 3.460 20.22 1 0 3 1 R> head(mutate(mtcars, cyl = NULL, hp = NULL, displ_l = disp / 61.0237)) mpg disp drat wt qsec vs am gear carb displ_l 1 21.0 160 3.90 2.620 16.46 0 1 4 4 2.621932 2 21.0 160 3.90 2.875 17.02 0 1 4 4 2.621932 3 22.8 108 3.85 2.320 18.61 1 1 4 1 1.769804 4 21.4 258 3.08 3.215 19.44 1 0 3 1 4.227866 5 18.7 360 3.15 3.440 17.02 0 0 3 2 5.899347 6 18.1 225 2.76 3.460 20.22 1 0 3 1 3.687092