r - 在一个数据框中找到字符串，然后在第二个数据框中替换它

一般来说，我有两个数据框:

主要一:

structure(list(mpg = c(21, 21, 22.8, 21.4, 18.7, 18.1, 14.3,
24.4, 22.8, 19.2, 17.8, 16.4, 17.3, 15.2, 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, 30.4, 15.8,
19.7, 15, 21.4), cyl = c(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),
    disp = c(160, 160, 108, 258, 360, 225, 360, 146.7, 140.8,
    167.6, 167.6, 275.8, 275.8, 275.8, 472, 460, 440, 78.7, 75.7,
    71.1, 120.1, 318, 304, 350, 400, 79, 120.3, 95.1, 351, 145,
    301, 121), hp = c(110, 110, 93, 110, 175, 105, 245, 62, 95,
    123, 123, 180, 180, 180, 205, 215, 230, 66, 52, 65, 97, 150,
    150, 245, 175, 66, 91, 113, 264, 175, 335, 109), drat = c(3.9,
    3.9, 3.85, 3.08, 3.15, 2.76, 3.21, 3.69, 3.92, 3.92, 3.92,
    3.07, 3.07, 3.07, 2.93, 3, 3.23, 4.08, 4.93, 4.22, 3.7, 2.76,
    3.15, 3.73, 3.08, 4.08, 4.43, 3.77, 4.22, 3.62, 3.54, 4.11
    ), wt = c(2.62, 2.875, 2.32, 3.215, 3.44, 3.46, 3.57, 3.19,
    3.15, 3.44, 3.44, 4.07, 3.73, 3.78, 5.25, 5.424, 5.345, 2.2,
    1.615, 1.835, 2.465, 3.52, 3.435, 3.84, 3.845, 1.935, 2.14,
    1.513, 3.17, 2.77, 3.57, 2.78), qsec = c(16.46, 17.02, 18.61,
    19.44, 17.02, 20.22, 15.84, 20, 22.9, 18.3, 18.9, 17.4, 17.6,
    18, 17.98, 17.82, 17.42, 19.47, 18.52, 19.9, 20.01, 16.87,
    17.3, 15.41, 17.05, 18.9, 16.7, 16.9, 14.5, 15.5, 14.6, 18.6
    ), vs = c(0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0,
    0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1), am = c(1,
    1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
    0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1), gear = c("a", "b", "c",
    "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o",
    "p", "r", "s", "t", "u", "w", "z", "a1", "b1", "c1", "d1",
    "e1", "f1", "g1", "h1", "i1"), carb = c("Mazda RX4", "Mazda RX4 Wag",
    "Datsun 710", "Hornet 4 Drive", "Hornet Sportabout", "Valiant",
    "Duster 360", "Merc 240D", "Merc 230", "Merc 280", "Merc 280C",
    "Merc 450SE", "Merc 450SL", "Merc 450SLC", "Cadillac Fleetwood",
    "Lincoln Continental", "Chrysler Imperial", "Fiat 128", "Honda Civic",
    "Toyota Corolla", "Toyota Corona", "Dodge Challenger", "AMC Javelin",
    "Camaro Z28", "Pontiac Firebird", "Fiat X1-9", "Porsche 914-2",
    "Lotus Europa", "Ford Pantera L", "Ferrari Dino", "Maserati Bora",
    "Volvo 142E")), .Names = c("mpg", "cyl", "disp", "hp", "drat",
"wt", "qsec", "vs", "am", "gear", "carb"), row.names = c(NA,
-32L), class = "data.frame")

名称表:

    structure(list(car = structure(c(18L, 18L, 19L, 19L, 5L, 13L,
14L, 31L, 7L, 21L, 20L, 22L, 23L, 24L, 25L, 26L, 2L, 15L, 4L,
9L, 12L, 29L, 30L, 6L, 1L, 3L, 27L, 10L, 28L, 16L, 11L, 11L,
8L, 17L, 32L, 32L), .Label = c("AMC Javelin", "Cadillac Fleetwood",
"Camaro Z28", "Chrysler Imperial", "Datsun 710", "Dodge Challenger",
"Duster 360", "Ferrari Dino", "Fiat 128", "Fiat X1-9", "Ford Pantera L",
"Honda Civic", "Hornet 4 Drive", "Hornet Sportabout", "Lincoln Continental",
"Lotus Europa", "Maserati Bora", "Mazda RX4", "Mazda RX4 Wag",
"Merc 230", "Merc 240D", "Merc 280", "Merc 280C", "Merc 450SE",
"Merc 450SL", "Merc 450SLC", "Pontiac Firebird", "Porsche 914-2",
"Toyota Corolla", "Toyota Corona", "Valiant", "Volvo 142E"), class = "factor"),
    owner = structure(c(15L, 25L, 9L, 8L, 4L, 7L, 31L, 22L, 17L,
    6L, 12L, 32L, 12L, 19L, 1L, 3L, 11L, 20L, 26L, 27L, 24L,
    29L, 16L, 1L, 2L, 13L, 9L, 26L, 23L, 10L, 18L, 14L, 30L,
    28L, 5L, 21L), .Label = c("Amid", "Armin", "Crane", "Dietmar",
    "Gared", "Gratea", "Hank", "Hannea", "Hans", "Heta", "Horse_with_no_name",
    "Jeff", "Krea", "Marea", "Mark", "Mattheus", "Micha", "Miko",
    "Myrcella", "Neil", "Nina", "Peter", "Rene", "Robert", "Steffan",
    "Tim", "Timon", "Timothy", "Uwe", "Vincent", "Wolfram", "Yena"
    ), class = "factor")), .Names = c("car", "owner"), row.names = c(NA,
-36L), class = "data.frame")

因此，我想使用owner的名称在主数据框中添加其他列。您可以在第二个数据中找到的每辆车的owners。

但:

正如您已经注意到的，有些汽车可能拥有不同的所有者。我不想在主数据框中创建其他行，因此我想将两个/三个或三个以上的所有者放在同一行中，但以逗号分隔。

最佳答案

尝试

library(data.table)
res <- setDT(df1, key='car')[df2][,c(.SD[1L],
           list(ownerN=toString(owner))), car][,owner:=NULL]
head(res,2)
#             car mpg cyl disp  hp drat    wt  qsec vs am gear carb
#1:     Mazda RX4  21   6  160 110  3.9 2.620 16.46  0  1    4    4
#2: Mazda RX4 Wag  21   6  160 110  3.9 2.875 17.02  0  1    4    4
#          ownerN
#1: Mark, Steffan
#2:  Hans, Hannea

或者，也可以对df2中的car的所有者进行paste编码，然后与df1联接

 dt2 <- setDT(df2)[, .(owner=toString(owner)), by= car]
 setkey(setDT(df1), car)[dt2]

数据

df1 <- cbind(mtcars, car=row.names(mtcars))
row.names(df1) <- NULL
df2[] <- lapply(df2, as.character)