子集数据

Question

我只需要快速帮助。 这是容易的任务，但我被困住了...

只是使用一个例子：

mtcars
                     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
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
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
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
Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8
Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

所以我只想保留在其他矩阵中可以找到名称的行：

> dput(list_names)
structure(c("Mazda RX4", "Mazda RX4 Wag", "Datsun 710", "Hornet 4 Drive", 
"Hornet Sportabout", "Duster 360", "Merc 240D", "Merc 230", 
"Merc 280", "Merc 280C", "Merc 450SE", "Merc 450SLC", 
"Cadillac Fleetwood", "Chrysler Imperial", 
"Fiat 128", "Honda Civic", "Toyota Corolla", "Toyota Corona", 
"Dodge Challenger", "AMC Javelin", "Camaro Z28", "Pontiac Firebird", 
"Fiat X1-9", "Lotus Europa", "Ford Pantera L", 
"Ferrari Dino", "Maserati Bora", "Volvo 142E"), .Dim = c(32L, 
1L))

如何有效地对其进行子集化？

Answer 1

使用%in%函数：

subset <- mtcars[row.names(mtcars) %in% list_names[,1],]

Answer 2

或者，您可以尝试：

mtcars[grep(paste(list_names, collapse="|"), row.names(mtcars)),]

假设数据集的row.name有多余的空格（前导/尾随空格）

mtcars1 <- mtcars
row.names(mtcars1)[9] <- "Merc  230 "
list_names <- c("Duster 360", "Merc 230", "Merc 280C", "Merc 280")
mtcars1[grep(paste(list_names, collapse="|"), row.names(mtcars1)),]
#            mpg cyl  disp  hp drat   wt  qsec vs am gear carb
#Duster 360 14.3   8 360.0 245 3.21 3.57 15.84  0  0    3    4
#Merc 230   22.8   4 140.8  95 3.92 3.15 22.90  1  0    4    2
#Merc 280   19.2   6 167.6 123 3.92 3.44 18.30  1  0    4    4
#Merc 280C  17.8   6 167.6 123 3.92 3.44 18.90  1  0    4    4