r语言 - 重构和格式化数据框列

Question

dfin <- 
ID   SEQ   GRP   C1   C2   C3   T1   T2   T3
1     1     1    0     5    8   0     1   2
1     2     1    5     10   15  5     6   7
2     1     2    20    25   30  0     1   2

C1是T1(TIME(处的浓度(CONC(等等。这是我想要的输出：

dfout <- 
ID   SEQ   GRP  CONC  TIME
1     1     1    0     0
1     1     1    5     1
1     1     1    8     2
1     2     1    5     5
1     2     1    10    6
1     2     1    15    7
2     1     2    20    0
2     1     2    25    1
2     1     2    30    2

dfin有更多的列用于Cx和Tx其中x是浓度读数的数量。

Answer 1

您可以使用data.table::melt来执行此操作，因为它能够根据列模式将表合并为多个列：

library(data.table)
melt(
setDT(df), 
id.vars=c("ID", "SEQ", "GRP"), 
# columns starts with C and T should be melted into two separate columns
measure.vars=patterns("^C", "^T"),     
value.name=c('CONC', 'TIME')
)[order(ID, SEQ)][, variable := NULL][]
#   ID SEQ GRP CONC TIME
#1:  1   1   1    0    0
#2:  1   1   1    5    1
#3:  1   1   1    8    2
#4:  1   2   1    5    5
#5:  1   2   1   10    6
#6:  1   2   1   15    7
#7:  2   1   2   20    0
#8:  2   1   2   25    1
#9:  2   1   2   30    2

---

或者，如果值列名称遵循模式[CT][0-9]，则可以通过指定sep=""来使用基 R 中的reshape，该由于此默认设置(来自 ？reshape(将通过字母/数字分隔来拆分值列名称：

split = if (sep == "") {
list(regexp = "[A-Za-z][0-9]", include = TRUE)
} else {
list(regexp = sep, include = FALSE, fixed = TRUE)}

reshape(df, varying=-(1:3), idvar=c("ID", "SEQ", "GRP"), 
dir="long", sep="", v.names=c("CONC", "TIME"))
#   ID SEQ GRP time CONC TIME
#1:  1   1   1    1    0    5
#2:  1   2   1    1    5   10
#3:  2   1   2    1   20   25
#4:  1   1   1    2    8    0
#5:  1   2   1    2   15    5
#6:  2   1   2    2   30    0
#7:  1   1   1    3    1    2
#8:  1   2   1    3    6    7
#9:  2   1   2    3    1    2