R語言中因子相關知識點詳解

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因子是用於對數據進行分類並將其存儲為級別的數據對象。 它們可以存儲字符串和整數。 它們在具有有限數量的唯一值的列中很有用。 像“男性”，“女性”和True，False等。它們在統計建模的數據分析中很有用。

使用factor()函數通過將向量作為輸入創建因子。

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))

當我們執行上面的代碼，它產生以下結果 –

 [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

數據幀的因子

在創建具有文本數據列的任何數據框時，R語言將文本列視為分類數據並在其上創建因子。

# 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)

當我們執行上面的代碼，它產生以下結果 –

  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

更改級別順序

可以通過使用新的等級次序再次應用因子函數來改變因子中的等級的順序。

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)

當我們執行上面的代碼，它產生以下結果 –

 [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

生成因子級別

我們可以使用gl()函數生成因子級別。 它需要兩個整數作為輸入，指示每個級別有多少級別和多少次。

語法

gl(n, k, labels)

以下是所使用的參數的說明 –

  • n是給出級數的整數。
  • k是給出復制數目的整數。
  • labels是所得因子水平的標簽向量。

例

v <- gl(3, 4, labels = c("Tampa", "Seattle","Boston"))
print(v)

當我們執行上面的代碼，它產生以下結果 –

Tampa   Tampa   Tampa   Tampa   Seattle Seattle Seattle Seattle Boston 
[10] Boston  Boston  Boston 
Levels: Tampa Seattle Boston

以上就是R語言中因子相關知識點詳解的詳細內容，更多關於R語言因子的資料請關註WalkonNet其它相關文章！

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