创建此功能时，我希望将用户filedata和cat_name的输入作为参数传递，但问题是这些输入存储在filedata和cat_name中不要传递函数内部。我无法理解为什么会这样。我该怎么办？
代码：
filename = file.choose()
filedata = read.csv(filename, stringsAsFactors = F)
cat_name = readline(prompt="Enter the categorical name to create its dummy variables: ")
function(filedata, cat_name)
{
data_cat=filedata[,cat_name]
if(class(data_cat)=="character")
{
freq=sort(table(data_cat))
freq=freq[-1]
for( i in names(freq))
{
colName = paste(cat_name,i,sep="_")
filedata[,colName] = ifelse(data_cat==freq[i],1,0)
}
filedata[,cat_name]=NULL
print("Successfully created dummy variables...")
} else
{
print("Please enter a categorical variable with character as its datatype")
}
return(filedata)
}
答案 0 :(得分：1)
您的代码存在两个问题。
很多指出的主要问题是虚拟创建功能没有名称。
要解决这个问题，只需将声明分配给变量即可。在这种情况下，我选择了make_dummies。
此帖子的主要问题是使用freq[i]为您提供计数，而不是要匹配的字符串。
# Make some data
n = 10
set.seed(112)
d = data.frame(id = 1:n,
cat_var = sample(letters,n, replace = T),
num_var = runif(n),
stringsAsFactors = F
)
tempcsv = tempfile()
write.csv(d, file=tempcsv, row.names = F)
id cat_var num_var
1 j 0.2359040
2 x 0.3471606
3 z 0.9049400
4 z 0.6322996
5 g 0.6743289
6 c 0.9700548
7 b 0.5604765
8 s 0.5553125
9 d 0.7432414
10 k 0.3701336
# Read that data in
filename = tempcsv # file.choose()
filedata = read.csv(filename, stringsAsFactors = F)
cat_name = "cat_var" #readline(prompt="Enter the categorical name to create its dummy variables: ")
make_dummies = function(filedata,cat_name)
{
data_cat=filedata[,cat_name]
if(class(data_cat)=="character")
{
freq=sort(table(data_cat))
freq=freq[-1]
for( i in names(freq))
{
colName = paste(cat_name,i,sep="_")
filedata[,colName] = ifelse(data_cat==i,1,0) # Note the change here
}
filedata[,cat_name]=NULL
print("Successfully created dummy variables...")
}else
{
print("Please enter a categorical variable with character as its datatype")
}
return(filedata)
}
(filedata = make_dummies(filedata, cat_name))
id num_var cat_var_c cat_var_d cat_var_g cat_var_j cat_var_k cat_var_s cat_var_x cat_var_z
1 1 0.2359040 0 0 0 1 0 0 0 0
2 2 0.3471606 0 0 0 0 0 0 1 0
3 3 0.9049400 0 0 0 0 0 0 0 1
4 4 0.6322996 0 0 0 0 0 0 0 1
5 5 0.6743289 0 0 1 0 0 0 0 0
6 6 0.9700548 1 0 0 0 0 0 0 0
7 7 0.5604765 0 0 0 0 0 0 0 0
8 8 0.5553125 0 0 0 0 0 1 0 0
9 9 0.7432414 0 1 0 0 0 0 0 0
10 10 0.3701336 0 0 0 0 1 0 0 0
此外，我强烈建议您使用 R 中的内置model.matrix()函数，并使用适当的转换factor代替string类型的数据。< / p>
例如：
model.matrix(~ cat_var - 1, filedata)
输出：
cat_vara cat_varg cat_varm cat_varo cat_vart cat_varu cat_varw cat_varz
1 1 0 0 0 0 0 0 0
2 1 0 0 0 0 0 0 0
3 0 0 0 0 0 0 1 0
4 0 0 1 0 0 0 0 0
5 0 1 0 0 0 0 0 0
6 0 0 0 0 1 0 0 0
7 0 0 0 0 1 0 0 0
8 0 0 0 0 0 1 0 0
9 0 0 0 0 0 0 0 1
10 0 0 0 1 0 0 0 0
答案 1 :(得分：0)
我注释掉的代码行仅被注释掉，因为它们阻止它成为可重现的示例。相反，我加载了一个内置数据集并使用它（而不是我的文件系统中的未知文件）。
#filename = file.choose()
#filedata = read.csv(filename, stringsAsFactors = F)
data("mtcars")
mtcars$cn <- row.names(mtcars)
filedata <- mtcars
#cat_name = readline(prompt="Enter the categorical name to create its dummy variables: ")
cat_name <- "cn"
colnames(filedata)
[1] "mpg" "cyl" "disp" "hp" "drat" "wt" "qsec" "vs" "am" "gear" "carb" "cn"
f<-
function(filedata, cat_name)
{
data_cat=filedata[,cat_name]
if(class(data_cat)=="character")
{
freq=sort(table(data_cat))
freq=freq[-1]
for( i in names(freq))
{
colName = paste(cat_name,i,sep="_")
filedata[,colName] = ifelse(data_cat==freq[i],1,0)
}
filedata[,cat_name]=NULL
print("Successfully created dummy variables...")
} else
{
print("Please enter a categorical variable with character as its datatype")
}
return(filedata)
}
filedata <- f(filedata,cat_name)
colnames(filedata)
[1] "mpg" "cyl" "disp" "hp" "drat" "wt" "qsec"
[8] "vs" "am" "gear" "carb" "cn_Cadillac Fleetwood" "cn_Camaro Z28" "cn_Chrysler Imperial"
[15] "cn_Datsun 710" "cn_Dodge Challenger" "cn_Duster 360" "cn_Ferrari Dino" "cn_Fiat 128" "cn_Fiat X1-9" "cn_Ford Pantera L"
[22] "cn_Honda Civic" "cn_Hornet 4 Drive" "cn_Hornet Sportabout" "cn_Lincoln Continental" "cn_Lotus Europa" "cn_Maserati Bora" "cn_Mazda RX4"
[29] "cn_Mazda RX4 Wag" "cn_Merc 230" "cn_Merc 240D" "cn_Merc 280" "cn_Merc 280C" "cn_Merc 450SE" "cn_Merc 450SL"
[36] "cn_Merc 450SLC" "cn_Pontiac Firebird" "cn_Porsche 914-2" "cn_Toyota Corolla" "cn_Toyota Corona" "cn_Valiant" "cn_Volvo 142E"