R 每隔一列 reshape 数据框

Question

这个问题已经有答案了:

Reshaping multiple sets of measurement columns (wide format) into single columns (long format) (8 个回答)

Gather multiple sets of columns (5 个回答)

已关闭 5 年前。

我很难整理一些以奇怪的方式获取的数据......它有一些患者标识符，然后是带有测试日期的列，然后是带有相应测量值的列。但随着时间的推移，它会重复进行相同的测试，并且数据位于后续列中。

数据框是这样的:

df1 <- data.frame(id = c("A","B"),
                 test1 = c("10-12-16", "12-10-17"),
                 test1_result = c("20", "3"),
                 test2 = c("10-01-17", "11-12-17"),
                 test2_result = c("18", "4"),
                 test3 = c("12-03-18", "NA"),
                 test3_result = c("300", "NA"))

我想获得这样的东西:

df2 <- data.frame(id = c("A", "A", "A", "B", "B", "B"),
                 tests = c("10-12-16", "10-01-17", "12-03-18", "12-10-17", "11-12-17", "NA"),
                 results = c("20", "18", "300", "3", "4", "NA")
                 )

我无法找到一种方法来改变它，任何帮助将非常感激。

谢谢!

Answer 1

您可以尝试从data.table中melt:

library(data.table)
setDT(df1)

df2 <- melt(df1, id = 'id', measure = patterns('test\\d$', '_result'))[
    , .(id, tests = value1, results = value2)]

#    id    tests results
# 1:  A 10-12-16      20
# 2:  B 12-10-17       3
# 3:  A 10-01-17      18
# 4:  B 11-12-17       4
# 5:  A 12-03-18     300
# 6:  B       NA      NA