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How to filter rows that contain a certain string in R?
We can do this by using filter and grepl function of dplyr package.
Example
Consider the mtcars data set.
> data(mtcars)
> head(mtcars)
mpg cyl disp hp drat wt qsec vs am gear carb
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
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
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
type
Mazda RX4 Mazda RX4
Mazda RX4 Wag Mazda RX4 Wag
Datsun 710 Datsun 710
Hornet 4 Drive Hornet 4 Drive
Hornet Sportabout Hornet Sportabout
Valiant Valiant
mtcars$type
[1] "Mazda RX4" "Mazda RX4 Wag" "Datsun 710"
[4] "Hornet 4 Drive" "Hornet Sportabout" "Valiant"
[7] "Duster 360" "Merc 240D" "Merc 230"
[10] "Merc 280" "Merc 280C" "Merc 450SE"
[13] "Merc 450SL" "Merc 450SLC" "Cadillac Fleetwood"
[16] "Lincoln Continental" "Chrysler Imperial" "Fiat 128"
[19] "Honda Civic" "Toyota Corolla" "Toyota Corona"
[22] "Dodge Challenger" "AMC Javelin" "Camaro Z28"
[25] "Pontiac Firebird" "Fiat X1-9" "Porsche 914-2"
[28] "Lotus Europa" "Ford Pantera L" "Ferrari Dino"
[31] "Maserati Bora" "Volvo 142E"let’s say we want to filter rows where we have type Ferrari then it can be done as follows −
> dplyr::filter(mtcars, grepl('Ferrari', type))
mpg cyl disp hp drat wt qsec vs am gear carb type
1 19.7 6 145 175 3.62 2.77 15.5 0 1 5 6 Ferrari DinoNow if we want to filter rows where we have type Merc or Datsun then it can be done as follows −
> dplyr::filter(mtcars, grepl('Merc|Datsun', type))
mpg cyl disp hp drat wt qsec vs am gear carb type
1 22.8 4 108.0 93 3.85 2.32 18.61 1 1 4 1 Datsun 710
2 24.4 4 146.7 62 3.69 3.19 20.00 1 0 4 2 Merc 240D
3 22.8 4 140.8 95 3.92 3.15 22.90 1 0 4 2 Merc 230
4 19.2 6 167.6 123 3.92 3.44 18.30 1 0 4 4 Merc 280
5 17.8 6 167.6 123 3.92 3.44 18.90 1 0 4 4 Merc 280C
6 16.4 8 275.8 180 3.07 4.07 17.40 0 0 3 3 Merc 450SE
7 17.3 8 275.8 180 3.07 3.73 17.60 0 0 3 3 Merc 450SL
8 15.2 8 275.8 180 3.07 3.78 18.00 0 0 3 3 Merc 450SLCSuppose if we want to filter rows where we don’t have type Mazda or Merc or Toyota then it can be done as follows −
> dplyr::filter(mtcars, !grepl('Mazda|Merc|Toyota', type))
mpg cyl disp hp drat wt qsec vs am gear carb type
1 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 Datsun 710
2 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 Hornet 4 Drive
3 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 Hornet Sportabout
4 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 Valiant
5 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 Duster 360
6 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4 Cadillac Fleetwood
7 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4 Lincoln Continental
8 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4 Chrysler Imperial
9 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 Fiat 128
10 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 Honda Civic
11 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2 Dodge Challenger
12 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2 AMC Javelin
13 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4 Camaro Z28
14 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2 Pontiac Firebird
15 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1 Fiat X1-9
16 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2 Porsche 914-2
17 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2 Lotus Europa
18 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4 Ford Pantera L
19 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6 Ferrari Dino
20 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8 Maserati Bora
21 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2 Volvo 142E
Updated on: 06-Jul-2020
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