因子是用于對(duì)數(shù)據(jù)進(jìn)行分類并將其存儲(chǔ)為級(jí)別的數(shù)據(jù)對(duì)象。它們可以存儲(chǔ)字符串和整數(shù)。 它們?cè)诰哂杏邢迶?shù)量的唯一值的列中很有用。 像“男”,“女”,“真”,“假”等。它們?cè)诮y(tǒng)計(jì)建模的數(shù)據(jù)分析中很有用。
因子可通過factor()
函數(shù)使用向量作為輸入來創(chuàng)建。
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))
當(dāng)我們執(zhí)行上述代碼時(shí),會(huì)產(chǎn)生以下結(jié)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
在使用一列文本數(shù)據(jù)創(chuàng)建數(shù)據(jù)幀時(shí),R將文本列視為分類數(shù)據(jù)并在其上創(chuàng)建因子。參考以下示例代碼 -
# 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)
當(dāng)我們執(zhí)行上述代碼時(shí),會(huì)產(chǎn)生以下結(jié)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
可以通過用新的級(jí)別順序再次應(yīng)用因子函數(shù)來改變因子中級(jí)別的順序。參考以下實(shí)現(xiàn)代碼 -
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)
當(dāng)我們執(zhí)行上述代碼時(shí),會(huì)產(chǎn)生以下結(jié)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
可以通過使用gl()
函數(shù)來生成因子級(jí)別。它需要兩個(gè)整數(shù)作為輸入,它表示每個(gè)級(jí)別有多少級(jí)別和多少次。
語法
gl(n, k, labels)
以下是使用的參數(shù)的描述 -
例子
v <- gl(3, 4, labels = c("Tampa", "Seattle","Boston"))
print(v)
當(dāng)我們執(zhí)行上述代碼時(shí),會(huì)產(chǎn)生以下結(jié)果 -
Tampa Tampa Tampa Tampa Seattle Seattle Seattle Seattle Boston
[10] Boston Boston Boston
Levels: Tampa Seattle Boston