后续跟踪：R中具有共享唯一行名称的匹配因子级别 [英] Follow-up: Matching factor levels in R with shared unique row names

问题描述

后续此帖。我们如何使用dplyr或data.table包来使因子级别与共享行名称相匹配？

In follow-up to this post. How do we use the dplyr or data.table package to match the factor levels appropriately with shared row names?

library(data.table)

(DT = data.table(a = LETTERS[c(1, 1:3, 8)], b = c(2, 4:7), 
                 c = as.factor(c("bob", "mary", "bob", "george", "alice")), key="a"))

#    a b      c
# 1: A 2    bob
# 2: A 4   mary
# 3: B 5    bob
# 4: C 6 george
# 5: H 7  alice

...并使用@frank的好答案：

...and using @frank 's great answer:

uc <- sort(unique(as.character(DT$c)))
( DT[,(uc):=lapply(uc,function(x)ifelse(c==x,b,NA))][,c('b','c'):=NULL] )

返回：

#   a alice bob george mary
# 1 A    NA   2     NA   NA
# 2 A    NA  NA     NA    4
# 3 B    NA   5     NA   NA
# 4 C    NA  NA      6   NA
# 5 H     7  NA     NA   NA

最后一个问题是，我们如何得到下面的输出，其中唯一的行名称共享级别值返回NA，保持？

And the final question here is, how do we get the below output, where unique row names share level values returning NAs where empty elements remain?

       alice bob george mary
# 1 A    NA   2      NA    4
# 2 B    NA   5      NA   NA
# 3 C    NA   NA      6   NA
# 4 H     7   NA     NA   NA

推荐答案

使用tidyr：

library(tidyr)
spread(DT, c, b)

这篇关于后续跟踪：R中具有共享唯一行名称的匹配因子级别的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！