Factors
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2023-12-01
因素是数据对象,用于对数据进行分类并将其存储为级别。 它们可以存储字符串和整数。 它们在具有有限数量的唯一值的列中很有用。 像“男性”,“女性”和“真,假”等。它们在统计建模的数据分析中很有用。
通过将矢量作为输入,使用factor ()函数创建factor () 。
例子 (Example)
# Create a vector as input.
data <- c("East","West","East","North","North","East","West","West","West","East","North")
print(data)
print(is.factor(data))
# Apply the factor function.
factor_data <- factor(data)
print(factor_data)
print(is.factor(factor_data))
当我们执行上面的代码时,它会产生以下结果 -
[1] "East" "West" "East" "North" "North" "East" "West" "West" "West" "East" "North"
[1] FALSE
[1] East West East North North East West West West East North
Levels: East North West
[1] TRUE
数据框架中的因素
在使用一列文本数据创建任何数据框时,R将文本列视为分类数据并在其上创建因子。
# Create the vectors for data frame.
height <- c(132,151,162,139,166,147,122)
weight <- c(48,49,66,53,67,52,40)
gender <- c("male","male","female","female","male","female","male")
# Create the data frame.
input_data <- data.frame(height,weight,gender)
print(input_data)
# Test if the gender column is a factor.
print(is.factor(input_data$gender))
# Print the gender column so see the levels.
print(input_data$gender)
当我们执行上面的代码时,它会产生以下结果 -
height weight gender
1 132 48 male
2 151 49 male
3 162 66 female
4 139 53 female
5 166 67 male
6 147 52 female
7 122 40 male
[1] TRUE
[1] male male female female male female male
Levels: female male
改变级别顺序
通过使用新的级别顺序再次应用因子函数,可以改变因子中级别的顺序。
data <- c("East","West","East","North","North","East","West",
"West","West","East","North")
# Create the factors
factor_data <- factor(data)
print(factor_data)
# Apply the factor function with required order of the level.
new_order_data <- factor(factor_data,levels = c("East","West","North"))
print(new_order_data)
当我们执行上面的代码时,它会产生以下结果 -
[1] East West East North North East West West West East North
Levels: East North West
[1] East West East North North East West West West East North
Levels: East West North
生成因子水平
我们可以使用gl()函数生成因子级别。 它需要两个整数作为输入,表示每个级别有多少级别和多少次。
语法 (Syntax)
gl(n, k, labels)
以下是所用参数的说明 -
n是一个给出级别数的整数。
k是给出复制次数的整数。
labels是结果因子水平的标签矢量。
例子 (Example)
v <- gl(3, 4, labels = c("Tampa", "Seattle","Boston"))
print(v)
当我们执行上面的代码时,它会产生以下结果 -
Tampa Tampa Tampa Tampa Seattle Seattle Seattle Seattle Boston
[10] Boston Boston Boston
Levels: Tampa Seattle Boston