$, [], [[]]

$:リスト要素にアクセスする。
[]:ベクトル要素にアクセスする。
[[]]:リスト要素にアクセスする。

mpg <- mtcars$mpg
mtcars[1]
##                      mpg
## Mazda RX4           21.0
## Mazda RX4 Wag       21.0
## Datsun 710          22.8
## Hornet 4 Drive      21.4
## Hornet Sportabout   18.7
## Valiant             18.1
## Duster 360          14.3
## Merc 240D           24.4
## Merc 230            22.8
## Merc 280            19.2
## Merc 280C           17.8
## Merc 450SE          16.4
## Merc 450SL          17.3
## Merc 450SLC         15.2
## Cadillac Fleetwood  10.4
## Lincoln Continental 10.4
## Chrysler Imperial   14.7
## Fiat 128            32.4
## Honda Civic         30.4
## Toyota Corolla      33.9
## Toyota Corona       21.5
## Dodge Challenger    15.5
## AMC Javelin         15.2
## Camaro Z28          13.3
## Pontiac Firebird    19.2
## Fiat X1-9           27.3
## Porsche 914-2       26.0
## Lotus Europa        30.4
## Ford Pantera L      15.8
## Ferrari Dino        19.7
## Maserati Bora       15.0
## Volvo 142E          21.4
mtcars[c(2,4)]
##                     cyl  hp
## Mazda RX4             6 110
## Mazda RX4 Wag         6 110
## Datsun 710            4  93
## Hornet 4 Drive        6 110
## Hornet Sportabout     8 175
## Valiant               6 105
## Duster 360            8 245
## Merc 240D             4  62
## Merc 230              4  95
## Merc 280              6 123
## Merc 280C             6 123
## Merc 450SE            8 180
## Merc 450SL            8 180
## Merc 450SLC           8 180
## Cadillac Fleetwood    8 205
## Lincoln Continental   8 215
## Chrysler Imperial     8 230
## Fiat 128              4  66
## Honda Civic           4  52
## Toyota Corolla        4  65
## Toyota Corona         4  97
## Dodge Challenger      8 150
## AMC Javelin           8 150
## Camaro Z28            8 245
## Pontiac Firebird      8 175
## Fiat X1-9             4  66
## Porsche 914-2         4  91
## Lotus Europa          4 113
## Ford Pantera L        8 264
## Ferrari Dino          6 175
## Maserati Bora         8 335
## Volvo 142E            4 109
#mtcars[,c(2,4)]
mtcars[,c(2:4)]
##                     cyl  disp  hp
## Mazda RX4             6 160.0 110
## Mazda RX4 Wag         6 160.0 110
## Datsun 710            4 108.0  93
## Hornet 4 Drive        6 258.0 110
## Hornet Sportabout     8 360.0 175
## Valiant               6 225.0 105
## Duster 360            8 360.0 245
## Merc 240D             4 146.7  62
## Merc 230              4 140.8  95
## Merc 280              6 167.6 123
## Merc 280C             6 167.6 123
## Merc 450SE            8 275.8 180
## Merc 450SL            8 275.8 180
## Merc 450SLC           8 275.8 180
## Cadillac Fleetwood    8 472.0 205
## Lincoln Continental   8 460.0 215
## Chrysler Imperial     8 440.0 230
## Fiat 128              4  78.7  66
## Honda Civic           4  75.7  52
## Toyota Corolla        4  71.1  65
## Toyota Corona         4 120.1  97
## Dodge Challenger      8 318.0 150
## AMC Javelin           8 304.0 150
## Camaro Z28            8 350.0 245
## Pontiac Firebird      8 400.0 175
## Fiat X1-9             4  79.0  66
## Porsche 914-2         4 120.3  91
## Lotus Europa          4  95.1 113
## Ford Pantera L        8 351.0 264
## Ferrari Dino          6 145.0 175
## Maserati Bora         8 301.0 335
## Volvo 142E            4 121.0 109
mtcars[0]
##  0 列 32 行のデータフレーム
mtcars[-c(2:11)]
##                      mpg
## Mazda RX4           21.0
## Mazda RX4 Wag       21.0
## Datsun 710          22.8
## Hornet 4 Drive      21.4
## Hornet Sportabout   18.7
## Valiant             18.1
## Duster 360          14.3
## Merc 240D           24.4
## Merc 230            22.8
## Merc 280            19.2
## Merc 280C           17.8
## Merc 450SE          16.4
## Merc 450SL          17.3
## Merc 450SLC         15.2
## Cadillac Fleetwood  10.4
## Lincoln Continental 10.4
## Chrysler Imperial   14.7
## Fiat 128            32.4
## Honda Civic         30.4
## Toyota Corolla      33.9
## Toyota Corona       21.5
## Dodge Challenger    15.5
## AMC Javelin         15.2
## Camaro Z28          13.3
## Pontiac Firebird    19.2
## Fiat X1-9           27.3
## Porsche 914-2       26.0
## Lotus Europa        30.4
## Ford Pantera L      15.8
## Ferrari Dino        19.7
## Maserati Bora       15.0
## Volvo 142E          21.4
mtcars["cyl"]
##                     cyl
## Mazda RX4             6
## Mazda RX4 Wag         6
## Datsun 710            4
## Hornet 4 Drive        6
## Hornet Sportabout     8
## Valiant               6
## Duster 360            8
## Merc 240D             4
## Merc 230              4
## Merc 280              6
## Merc 280C             6
## Merc 450SE            8
## Merc 450SL            8
## Merc 450SLC           8
## Cadillac Fleetwood    8
## Lincoln Continental   8
## Chrysler Imperial     8
## Fiat 128              4
## Honda Civic           4
## Toyota Corolla        4
## Toyota Corona         4
## Dodge Challenger      8
## AMC Javelin           8
## Camaro Z28            8
## Pontiac Firebird      8
## Fiat X1-9             4
## Porsche 914-2         4
## Lotus Europa          4
## Ford Pantera L        8
## Ferrari Dino          6
## Maserati Bora         8
## Volvo 142E            4
# 1番目の列
mtcars[[1]]
##  [1] 21.0 21.0 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 15.2
## [15] 10.4 10.4 14.7 32.4 30.4 33.9 21.5 15.5 15.2 13.3 19.2 27.3 26.0 30.4
## [29] 15.8 19.7 15.0 21.4
# 'cyl'の列
mtcars[["cyl"]]
##  [1] 6 6 4 6 8 6 8 4 4 6 6 8 8 8 8 8 8 4 4 4 4 8 8 8 8 4 4 4 8 6 8 4
# 'Datson 170'の'wt'にアクセス
mtcars[[2,"wt"]]
## [1] 2.875

head, tail

head:データの先頭行をn行抽出する。
tail:データの最終行からn行抽出する。

head(mtcars,3)
##                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
tail(mtcars,5)
##                 mpg cyl  disp  hp drat    wt qsec vs am gear carb
## Lotus Europa   30.4   4  95.1 113 3.77 1.513 16.9  1  1    5    2
## Ford Pantera L 15.8   8 351.0 264 4.22 3.170 14.5  0  1    5    4
## Ferrari Dino   19.7   6 145.0 175 3.62 2.770 15.5  0  1    5    6
## Maserati Bora  15.0   8 301.0 335 3.54 3.570 14.6  0  1    5    8
## Volvo 142E     21.4   4 121.0 109 4.11 2.780 18.6  1  1    4    2

subset

データを条件で検索する。

subset(mtcars,cyl <= 4)
##                 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
## 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
## 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
## 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
## Volvo 142E     21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2
# am:a=automatic and max(mpg)
subset(mtcars, am == 1 & mpg == max(mpg))
##                 mpg cyl disp hp drat    wt qsec vs am gear carb
## Toyota Corolla 33.9   4 71.1 65 4.22 1.835 19.9  1  1    4    1

複数条件では、& (AND条件), | (OR条件)を使う。

with

データフレームで列にアクセスする場合、列名を省略できる関数。

# 燃費(mpg)のZ値を求める
z <- (mtcars$mpg - mean(mtcars$mpg)) / sd(mtcars$mpg)
z
##  [1]  0.15088482  0.15088482  0.44954345  0.21725341 -0.23073453
##  [6] -0.33028740 -0.96078893  0.71501778  0.44954345 -0.14777380
## [11] -0.38006384 -0.61235388 -0.46302456 -0.81145962 -1.60788262
## [16] -1.60788262 -0.89442035  2.04238943  1.71054652  2.29127162
## [21]  0.23384555 -0.76168319 -0.81145962 -1.12671039 -0.14777380
## [26]  1.19619000  0.98049211  1.71054652 -0.71190675 -0.06481307
## [31] -0.84464392  0.21725341
z1 <- with(mtcars, (mpg - mean(mpg)) / sd(mpg))
z1
##  [1]  0.15088482  0.15088482  0.44954345  0.21725341 -0.23073453
##  [6] -0.33028740 -0.96078893  0.71501778  0.44954345 -0.14777380
## [11] -0.38006384 -0.61235388 -0.46302456 -0.81145962 -1.60788262
## [16] -1.60788262 -0.89442035  2.04238943  1.71054652  2.29127162
## [21]  0.23384555 -0.76168319 -0.81145962 -1.12671039 -0.14777380
## [26]  1.19619000  0.98049211  1.71054652 -0.71190675 -0.06481307
## [31] -0.84464392  0.21725341

assign

名前xに、オブジェクト値Valueを割り当てる。

# 'file3'に33を割り当てる
assign(paste("file", 3, sep=""), 33)
file3
## [1] 33

get

オブジェクトの名前を指定すると、そのオブジェクトを取得する。

m <- mtcars
get("m")
##                      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
最終更新日:2016/04/27

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