Factor (factor) and ordered factor (ordered factor)
Factors are used to store categorical variables (categorical variables) and ordered variables, which cannot be used to calculate but only to classify or count. Factors represent categorical variables, and ordered factors represent ordered variables.
The function that generates the factor data object is factor (), the syntax is factor (data, levels, labels, ...), where data is the parameter, levels is the factor horizontal vector, and labels is the label vector of the factor.
1. Create a factor.
Example 1:colour <-C (' G ', ' g ', ' r ', ' Y ', ' g ', ' y ', ' y ', ' r ', ' Y ')
Col <-factor (colour)
Col1 <-factor (colour, levels = C (' G ', ' R ', ' Y '), labels = c (' Green ', ' Red ', ' Yellow '))
#labels的内容替换colour相应位置对应levels的内容 col1
[1] Green green red Yellow green Yellow Yellow Red Yellow
Levels:green Red Yellow
Col2 <-factor (colour, levels = C (' G ', ' R ', ' Y '), labels = c (' 1 ', ' 2 ', ' 3 '))
Col_vec <-as.vector (col2) #转换成字符向量 "1" "1" "2" "3" "1" "3" "3" "2" "3"
Col_num <-as.numeric (col2) #转换成数字向量 1 1 2 3 1 3 3 2 3
Col3 <-factor (colour, levels = C (' G ', ' R '))
[1] G G r <NA> G <NA> <NA> R <NA>
Levels:g R
2. Create an ordered factor
Example 1:score <-C (' A ', ' B ', ' A ', ' C ', ' B ')
Score1 <-ordered (score, levels = C (' C ', ' B ', ' A ')); Score1
[1] A B a C b
Levels:c < B < A
3. Use the Cut () function to convert the general data to the cause or order factor.
Example 1:exam <-C (98, 97, 52, 88, 85, 75, 97, 92, 77, 74, 70, 63, 97, 71, 98,
65, 79, 74, 58, 59, 60, 63, 87, 82, 95, 75, 79, 96, 50, 88)
EXAM1 <-cut (exam, breaks = 3) #切分成3组
EXAM2 <-cut (exam, breaks = C (0, D, D, D,)) #切分成自己设置的组
attr (exam1, ' levels '); attr (exam2, ' levels '); attr (exam2, ' class ')
Ordered (exam2, labels = c (' bad ', ' OK ', ' average ', ' good ', ' excellent ')) #一个有序因子
Factors in the R language
