R dplyr.筛选包含一列数值向量的数据框 [英] R dplyr. Filter a dataframe that contains a column of numeric vectors

问题描述

我有一个数据框，其中一列包含数值向量.我想根据涉及该列的条件来过滤行.这是一个简化的示例.

I have a dataframe in which one column contains numeric vectors. I want to filter rows based on a condition involving that column. This is a simplified example.

df <- data.frame(id = LETTERS[1:3], name=c("Alice", "Bob", "Carol"))
mylist=list(c(1,2,3), c(4,5), c(1,3,4))  
df$numvecs <- mylist
df
#   id  name   numvecs
# 1  A  Alice  1, 2, 3
# 2  B  Bob    4, 5
# 3  C  Carol  1, 3, 4

我可以使用诸如mapply之类的东西

I can use something like mapply e.g.

mapply(function(x,y) x=="B" & 4 %in% y, df$id, df$numvecs)

第二行正确返回TRUE，第一行和第二行返回FALSE.

which correctly returns TRUE for the second row, and FALSE for rows 1 and 2.

但是，我有理由要使用dplyr过滤器而不是mapply，但是我无法使dplyr过滤器在numvecs列上正确运行.而不是返回两行，下面的命令不返回任何行.

However, I have reasons why I'd like to use dplyr filter instead of mapply, but I can't get dplyr filter to operate correctly on the numvecs column. Instead of returning two rows, the following returns no rows.

filter(df, 4 %in% numvecs)
# [1] id      numvecs
#    <0 rows> (or 0-length row.names)

我在这里想念什么?如何过滤涉及numvecs列的条件表达式?

What am I missing here? How can I filter on a conditional expression involving the numvecs column?

理想情况下，我也想使用非标准评估filter_，因此我可以将过滤条件作为参数传递.任何帮助表示赞赏.谢谢.

And ideally I'd like to use the non-standard evaluation filter_ as well, so I can pass the filter condition as an argument. Any help appreciated. Thanks.

推荐答案

我们仍然可以将 mapply 与 filter

filter(df, mapply(function(x,y) x == "B" & 4 %in% y, id, numvecs))
#  id name numvecs
#1  B  Bob    4, 5

---

或使用 purrr

library(purrr)
filter(df, unlist(map(numvecs, ~4 %in% .x)))
#  id  name numvecs
#1  B   Bob    4, 5
#2  C Carol 1, 3, 4

或者我们也可以连锁进行

Or we can also do this in chain

df %>%
    .$numvecs %>% 
     map( ~ 4 %in% .x) %>%
     unlist %>% 
     df[.,]
#  id  name numvecs
#2  B   Bob    4, 5
#3  C Carol 1, 3, 4

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