因素是用于对数据进行分类并将其存储为级别的数据对象.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.
使用 factor()函数创建因子通过将矢量作为输入.
示例
# 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 NorthLevels: East North West[1] TRUE
数据框中的因素
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 gender1 132 48 male2 151 49 male3 162 66 female4 139 53 female5 166 67 male6 147 52 female7 122 40 male[1] TRUE[1] male male female female male female male Levels: female male
更改级别顺序
因子的级别顺序可以通过应用因子函数再次使用新的水平顺序.
data <- c("East","West","East","North","North","East","West", "West","West","East","North")# Create the factorsfactor_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,它产生以下结果 :
[1] East West East North North East West West West East NorthLevels: East North West [1] East West East North North East West West West East NorthLevels: East West North
生成因子水平
我们可以使用 gl()函数生成因子水平.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
gl(n,k,labels)
以下是所用参数的说明及减号;
n 是一个给出级别数的整数.
k 是一个给出复制次数的整数.
标签是结果因素的标签向量等级.
示例
v <- gl(3, 4, labels = c("Tampa", "Seattle","Boston"))print(v)
当我们执行上面的代码时,它产生以下结果 :
Tampa Tampa Tampa Tampa Seattle Seattle Seattle Seattle Boston [10] Boston Boston Boston Levels: Tampa Seattle Boston