合并R中的x - 将字符转换为NA

Question

我有3个xts对象

logged <- xts::xts(x = loggedInUsers$loggedInUsers, order.by = Sys.time())
loadValue <- xts::xts(x = loadAvg, order.by = Sys.time())
hostname <- xts::xts(x = loadHost, order.by = Sys.time())

dput(hostname)
dput(loadValue)
dput(logged)

dput给出以下结果

 structure("deliverforgoodportal", .Dim = c(1L, 1L), index = structure(1551088127.27724, tzone = "", tclass = c("POSIXct",
    "POSIXt")), class = c("xts", "zoo"), .indexCLASS = c("POSIXct",
    "POSIXt"), tclass = c("POSIXct", "POSIXt"), .indexTZ = "", tzone = "")

structure(0, .Dim = c(1L, 1L), .Dimnames = list(NULL, "load"), index = structure(1551088127.27676, tzone = "", tclass = c("POSIXct",
"POSIXt")), .indexCLASS = c("POSIXct", "POSIXt"), tclass = c("POSIXct",
"POSIXt"), .indexTZ = "", tzone = "", class = c("xts", "zoo"))

structure(1, .Dim = c(1L, 1L), index = structure(1551088127.27637, tzone = "", tclass = c("POSIXct",
"POSIXt")), class = c("xts", "zoo"), .indexCLASS = c("POSIXct",
"POSIXt"), tclass = c("POSIXct", "POSIXt"), .indexTZ = "", tzone = "")

当我合并这三个并打印时，主机名将转换为NA

  tmp <- merge.xts(hostname, logged, loadValue, all = TRUE)
    print(tmp)

输出为:(主机名为NA）

                    hostname logged  load
2019-02-25 09:48:47       NA      1    NA
2019-02-25 09:48:47       NA     NA    0
2019-02-25 09:48:47       NA     NA    NA

为什么这会成为NA？

Answer 1

您应该意识到xts对象是时间序列和矩阵。现在矩阵只能包含一种类型的值，无论是字符还是数字。但不是两个。您的合并尝试将字符值矩阵（主机名）与数值（已记录和加载）组合在一起。这导致主机名值被强制转换为NA。

如果要加入此数据，则必须使用data.frame（或data.table）。另请注意，您的时间值不相等，它们是毫秒。因此，如果你想在几分钟内加入，首先使用来自lubridate包的floor_date。见下面两个有和没有lubridate的例子。我使用包timetk将xts对象转换为tibble，但取决于您可能不需要的源数据。

with full_join，no lubridate

library(timetk)
library(dplyr)
hostname <- tk_tbl(hostname)
loadValue <- tk_tbl(loadValue)
logged <- tk_tbl(logged)

hostname %>% 
  full_join(loadValue) %>% 
  full_join(logged, 
            by = "index", 
            suffix = c("_hostname", "_logged"))

Joining, by = "index"
# A tibble: 3 x 4
  index               value_hostname        load value_logged
  <dttm>              <chr>                <dbl>        <dbl>
1 2019-02-25 10:48:47 deliverforgoodportal    NA           NA
2 2019-02-25 10:48:47 NA                       0           NA
3 2019-02-25 10:48:47 NA                      NA            1

与lubridate和左连接：

hostname %>% 
  mutate(index = lubridate::floor_date(index, unit = "seconds")) %>% 
  left_join(loadValue %>% mutate(index = lubridate::floor_date(index, unit = "seconds"))) %>% 
  left_join(logged %>% mutate(index = lubridate::floor_date(index, unit = "seconds")), 
            by = "index", 
            suffix = c("_hostname", "_logged"))    

Joining, by = "index"
# A tibble: 1 x 4
  index               value_hostname        load value_logged
  <dttm>              <chr>                <dbl>        <dbl>
1 2019-02-25 10:48:47 deliverforgoodportal     0            1