我有一个数据框＆＃34; mydf＆＃34;使用以下内容创建：
x <- rep(1,100)
y <- rnorm(100,1)
z <- rep("A",25)
z <- append(append(append(z, rep("B",25)), rep("C",25)), rep("D",25))
mydf <- as.data.frame(cbind(x,y,z))
正如您所注意到的，z有四个不同的值（A，B，C和D）。 现在我要做的是创建四个名为z_A，z_B，z_C和z_D的新字段，其中每个字段都填充0或1.如果mydf $ z == A，则z_A应为1.如果mydf $ z == B ，那么z_B应为1，否则为0，依此类推每个值。
虽然我现在只在mydf $ z中有四个不同的值，但是我试图使用通用函数，我可以使用它来对任何可以包含任意数量的不同值的列进行二值化。
我查看了StackOverflow上的另一个示例，例如：
a <- model.matrix( ~ z - 1, data=mydf)
当列只有字符值时效果很好。
> a
zA zB zC zD
1 1 0 0 0
2 1 0 0 0
3 1 0 0 0
4 1 0 0 0
5 1 0 0 0
6 1 0 0 0
7 1 0 0 0
8 1 0 0 0
9 1 0 0 0
10 1 0 0 0
当我尝试将z列作为数字变量时：
x <- rep(1,100)
y <- rnorm(100,1)
z <- rep(1,25)
z <- append(append(append(z, rep(2,25)), rep(3,25)), rep(4,25))
mydf <- as.data.frame(cbind(x,y,z))
c <- model.matrix( ~ z - 1, data=mydf)
c
我明白了：
> c
z
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 1
如果我尝试将所需的变量设置为字符，我会得到以下内容，除了字段名称都很复杂之外：
c <- model.matrix( ~ as.character(z) - 1, data=mydf)
> c
as.character(z)1 as.character(z)2 as.character(z)3 as.character(z)4
1 1 0 0 0
2 1 0 0 0
3 1 0 0 0
4 1 0 0 0
5 1 0 0 0
6 1 0 0 0
7 1 0 0 0
8 1 0 0 0
9 1 0 0 0
10 1 0 0 0
如果有其他信息有助于解决此问题，请与我们联系。
谢谢！
编辑： 这是Howard的反馈中一些实际数据的示例。
dput(head(df,100))
structure(list(datetime = structure(c(14975, 14975, 14975, 14975,
14975, 14975, 14975, 14975, 14975, 14975, 14975, 14975, 14975,
14975, 14975, 14975, 14975, 14975, 14975, 14975, 14975, 14975,
14975, 14975, 14976, 14976, 14976, 14976, 14976, 14976, 14976,
14976, 14976, 14976, 14976, 14976, 14976, 14976, 14976, 14976,
14976, 14976, 14976, 14976, 14976, 14976, 14976, 14977, 14977,
14977, 14977, 14977, 14977, 14977, 14977, 14977, 14977, 14977,
14977, 14977, 14977, 14977, 14977, 14977, 14977, 14977, 14977,
14977, 14977, 14978, 14978, 14978, 14978, 14978, 14978, 14978,
14978, 14978, 14978, 14978, 14978, 14978, 14978, 14978, 14978,
14978, 14978, 14978, 14978, 14978, 14978, 14978, 14979, 14979,
14979, 14979, 14979, 14979, 14979, 14979), class = "Date"), season = c(1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L), holiday = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), workingday = c(0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L), weather = c(1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 2L, 2L, 2L, 2L, 2L,
2L, 2L, 2L, 2L, 3L, 2L, 3L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 1L,
2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), temp = c(9.84, 9.02,
9.02, 9.84, 9.84, 9.84, 9.02, 8.2, 9.84, 13.12, 15.58, 14.76,
17.22, 18.86, 18.86, 18.04, 17.22, 18.04, 17.22, 17.22, 16.4,
16.4, 16.4, 18.86, 18.86, 18.04, 17.22, 18.86, 18.86, 17.22,
16.4, 16.4, 15.58, 14.76, 14.76, 14.76, 14.76, 14.76, 13.94,
13.94, 13.94, 14.76, 13.12, 12.3, 10.66, 9.84, 9.02, 9.02, 8.2,
6.56, 6.56, 5.74, 5.74, 5.74, 6.56, 7.38, 8.2, 9.02, 9.84, 10.66,
10.66, 10.66, 9.84, 9.84, 8.2, 8.2, 7.38, 5.74, 7.38, 6.56, 6.56,
5.74, 5.74, 4.92, 4.92, 4.92, 5.74, 6.56, 6.56, 9.02, 9.02, 9.84,
10.66, 11.48, 12.3, 11.48, 10.66, 9.84, 9.84, 9.02, 9.02, 8.2,
8.2, 6.56, 6.56, 9.84, 9.02, 8.2, 7.38, 8.2), atemp = c(14.395,
13.635, 13.635, 14.395, 14.395, 12.88, 13.635, 12.88, 14.395,
17.425, 19.695, 16.665, 21.21, 22.725, 22.725, 21.97, 21.21,
21.97, 21.21, 21.21, 20.455, 20.455, 20.455, 22.725, 22.725,
21.97, 21.21, 22.725, 22.725, 21.21, 20.455, 20.455, 19.695,
17.425, 16.665, 16.665, 17.425, 17.425, 16.665, 16.665, 16.665,
16.665, 14.395, 13.635, 11.365, 10.605, 11.365, 9.85, 8.335,
6.82, 6.82, 5.305, 6.82, 6.06, 6.82, 8.335, 9.09, 10.605, 10.605,
12.12, 12.12, 12.12, 11.365, 12.88, 12.88, 11.365, 9.85, 7.575,
10.605, 9.09, 9.09, 7.575, 9.09, 7.575, 7.575, 7.575, 7.575,
7.575, 6.82, 10.605, 11.365, 11.365, 12.88, 13.635, 14.395, 13.635,
12.88, 12.88, 12.88, 13.635, 12.88, 11.365, 12.88, 9.85, 9.85,
11.365, 11.365, 9.85, 9.09, 9.09), humidity = c(81L, 80L, 80L,
75L, 75L, 75L, 80L, 86L, 75L, 76L, 76L, 81L, 77L, 72L, 72L, 77L,
82L, 82L, 88L, 88L, 87L, 87L, 94L, 88L, 88L, 94L, 100L, 94L,
94L, 77L, 76L, 71L, 76L, 81L, 71L, 66L, 66L, 76L, 81L, 71L, 57L,
46L, 42L, 39L, 44L, 44L, 47L, 44L, 44L, 47L, 47L, 50L, 50L, 50L,
43L, 43L, 40L, 35L, 35L, 30L, 30L, 30L, 30L, 32L, 47L, 47L, 64L,
69L, 55L, 55L, 59L, 63L, 63L, 68L, 74L, 74L, 69L, 64L, 69L, 51L,
51L, 56L, 52L, 52L, 49L, 48L, 48L, 48L, 48L, 64L, 64L, 69L, 64L,
74L, 74L, 48L, 47L, 47L, 43L, 40L), windspeed = c(0, 0, 0, 0,
0, 6.0032, 0, 0, 0, 0, 16.9979, 19.0012, 19.0012, 19.9995, 19.0012,
19.9995, 19.9995, 19.0012, 16.9979, 16.9979, 16.9979, 12.998,
15.0013, 19.9995, 19.9995, 16.9979, 19.0012, 12.998, 12.998,
19.9995, 12.998, 15.0013, 15.0013, 15.0013, 16.9979, 19.9995,
8.9981, 12.998, 11.0014, 11.0014, 12.998, 22.0028, 30.0026, 23.9994,
22.0028, 19.9995, 11.0014, 23.9994, 27.9993, 26.0027, 19.0012,
26.0027, 12.998, 19.0012, 26.0027, 16.9979, 22.0028, 19.9995,
19.0012, 19.0012, 16.9979, 16.9979, 15.0013, 7.0015, 0, 7.0015,
8.9981, 8.9981, 7.0015, 7.0015, 7.0015, 8.9981, 6.0032, 7.0015,
7.0015, 8.9981, 11.0014, 15.0013, 22.0028, 19.9995, 11.0014,
12.998, 15.0013, 16.9979, 16.9979, 15.0013, 12.998, 7.0015, 7.0015,
0, 6.0032, 6.0032, 0, 6.0032, 6.0032, 15.0013, 11.0014, 15.0013,
12.998, 19.9995), casual = c(3L, 8L, 5L, 3L, 0L, 0L, 2L, 1L,
1L, 8L, 12L, 26L, 29L, 47L, 35L, 40L, 41L, 15L, 9L, 6L, 11L,
3L, 11L, 15L, 4L, 1L, 1L, 2L, 2L, 0L, 0L, 0L, 1L, 7L, 16L, 20L,
11L, 4L, 19L, 9L, 7L, 10L, 1L, 5L, 11L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 1L, 1L, 7L, 11L, 10L, 13L, 8L, 11L, 14L, 9L, 11L, 9L, 8L,
3L, 3L, 0L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 2L, 2L, 2L, 5L, 7L, 12L,
18L, 9L, 17L, 15L, 10L, 3L, 2L, 1L, 0L, 1L, 2L, 0L, 0L, 0L, 0L,
0L, 0L, 1L, 3L), registered = c(13L, 32L, 27L, 10L, 1L, 1L, 0L,
2L, 7L, 6L, 24L, 30L, 55L, 47L, 71L, 70L, 52L, 52L, 26L, 31L,
25L, 31L, 17L, 24L, 13L, 16L, 8L, 4L, 1L, 2L, 1L, 8L, 19L, 46L,
54L, 73L, 64L, 55L, 55L, 67L, 58L, 43L, 29L, 17L, 20L, 9L, 8L,
5L, 2L, 1L, 3L, 30L, 63L, 153L, 81L, 33L, 41L, 48L, 53L, 66L,
58L, 67L, 146L, 148L, 102L, 49L, 49L, 20L, 11L, 5L, 2L, 1L, 2L,
4L, 36L, 92L, 177L, 98L, 37L, 50L, 66L, 79L, 54L, 48L, 68L, 202L,
179L, 110L, 53L, 48L, 34L, 9L, 6L, 6L, 2L, 2L, 3L, 33L, 87L,
192L), count = c(16L, 40L, 32L, 13L, 1L, 1L, 2L, 3L, 8L, 14L,
36L, 56L, 84L, 94L, 106L, 110L, 93L, 67L, 35L, 37L, 36L, 34L,
28L, 39L, 17L, 17L, 9L, 6L, 3L, 2L, 1L, 8L, 20L, 53L, 70L, 93L,
75L, 59L, 74L, 76L, 65L, 53L, 30L, 22L, 31L, 9L, 8L, 5L, 2L,
1L, 3L, 30L, 64L, 154L, 88L, 44L, 51L, 61L, 61L, 77L, 72L, 76L,
157L, 157L, 110L, 52L, 52L, 20L, 12L, 5L, 2L, 1L, 2L, 4L, 36L,
94L, 179L, 100L, 42L, 57L, 78L, 97L, 63L, 65L, 83L, 212L, 182L,
112L, 54L, 48L, 35L, 11L, 6L, 6L, 2L, 2L, 3L, 33L, 88L, 195L)), .Names = c("datetime",
"season", "holiday", "workingday", "weather", "temp", "atemp",
"humidity", "windspeed", "casual", "registered", "count"), row.names = c("1",
"2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13",
"14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24",
"25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35",
"36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46",
"47", "48", "49", "50", "51", "52", "53", "54", "55", "56", "57",
"58", "59", "60", "61", "62", "63", "64", "65", "66", "67", "68",
"69", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79",
"80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "90",
"91", "92", "93", "94", "95", "96", "97", "98", "99", "100"), class = "data.frame")
在这种情况下，我想创建df $ season1，df $ season2，df $ season3和df $ season4。 我在这种情况下的问题是，我是否必须输入数据集中的每一列（请参阅下面的dcast），只是为了添加season1，season2，season3和season4字段？ AND，有没有办法将它们命名为season1，season2，season3，season4而不是1,2,3,4？
library(reshape2)
result <- dcast(df,datetime + holiday + workingday + weather +
temp + atemp + humidity + windspeed + casual +
registered + count ~ season,length)
答案 0 :(得分：3)
您可以尝试：
cbind(mydf,sapply(levels(mydf$z), function(x) as.numeric(mydf$z==x)))
# x y z A B C D
#1 1 1.68876859502969 A 1 0 0 0
#2 1 0.408336901490438 A 1 0 0 0
#3 1 -0.115258225333019 A 1 0 0 0
#4 1 1.64286711975319 A 1 0 0 0
#5 1 0.393874649038152 A 1 0 0 0
#6 1 1.55492320680662 A 1 0 0 0
答案 1 :(得分：2)
喜欢这个吗？
library(reshape2)
result <- dcast(mydf,x+y~z,length)
head(result)
# x y A B C D
# 1 1 -0.000774423151445491 0 0 1 0
# 2 1 -0.0206607799566461 1 0 0 0
# 3 1 -0.0374524778732928 1 0 0 0
# 4 1 -0.155943108886233 0 0 1 0
# 5 1 -0.174550152789981 0 0 0 1
# 6 1 -0.183201143770777 0 0 1 0
这是按x和y排序，这可能是不可取的。