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我想从长格式数据框中的所有标记项中减去具有标签“baseline”的行中的值。使用带“基线”子集的left_join分两步完成此操作非常简单。然而,我不知道如何将vas_1
和vas_diff
合并成一个链。dplyr自动加入过滤器
library(dplyr)
# Create test data
n_users = 5
vas = data_frame(
user = rep(letters[1:n_users], each = 3),
group = rep(c("baseline", "early", "late"),n_users),
vas = round(rgamma(n_users*3, 10,1.4))
)
# The above data are given
# Assume some other operations are required
vas_1 = vas %>%
mutate(
vas = vas * 2
)
# I want to put the following into one
# chain with the above
# Use self-join to subtract baseline
vas_diff = vas_1 %>%
filter(group != "baseline") %>%
# Problem is vas_1 here. Using . gives error here
# Adding copy = TRUE does not help
# left_join(. %>% filter(group == "baseline") , by = c("user")) %>%
left_join(vas_1 %>% filter(group == "baseline") , by = c("user")) %>%
mutate(vas = vas.x - vas.y) %>% # compute offset
select(user, group.x, vas) # remove temporary variables
vas_diff
那么期望的结果是什么?你的代码有效。你只是想简化它,或者你想要一个不同的结果? –
不,结果很好。我对dplyr的内部工作感兴趣,特别是点的魔力。并试图了解错误消息,请求复制,甚至与“复制”失败 –
不太确定我理解你的问题,但问题似乎是,你过滤掉所有观察'组==“基线”,然后,稍后在管道中,您想要再次访问这些行,但它们不再处于数据中。也许你想要像'vas_1%>%left_join(filter(。,group!=“baseline”),filter(。,group ==“baseline”),by = c(“user”))''? –