r - 如何计算数据框中的元素出现在另一个数据框中的次数

Question

我有 2 个数据框。一个是供应商列表:

      vendor
1     apple
2     samsung
3     whirlpool
etc
.
.
.

另一篇是关于特定供应商的文章:

nbr     title     content
1       title 1   This is an article about apple
2       title 2   This is an article about whirlpool
3       title 3   This is an article about samsung
4       title 4   This is an article about apple and samsung
5       title 5   This is an article about none of them
etc
.
.
.

我已经尝试使用 stringr 包中的许多函数，但我不想只计算一个术语，我想计算整个供应商列表。我试过使用 dplyr 进行分组和计数，但我也无法按照我想要的方式工作。

最后，我想得到 2 个输出:每个供应商在所有文章中被提及的次数。

apple       2
samsung     2
whirlpool   1
etc.
.
.
.

我还想查看每个供应商在一篇文章中被提及的次数:

title     apple     samsung     whirlpool    etc...
title 1       1
title 2                                 1
title 3                   1
title 4       1           1
title 5
etc.
.
.
.

Answer 1

这是一种解决方案:

mentions = stringr::str_extract_all(art$content, pattern = paste(v$vendor, collapse = "|"))
table(unlist(lapply(mentions, unique)))
# apple   samsung whirlpool 
#     2         2         1 

mentions = lapply(mentions, factor, levels = v$vendor)
t(sapply(mentions, table))
#         apple samsung whirlpool
# title 1     1       0         0
# title 2     0       0         1
# title 3     0       1         0
# title 4     1       1         0
# title 5     0       0         0

使用此数据:

v = read.table(text = "      vendor
1     apple
2     samsung
3     whirlpool", header = T, stringsAsFactors = F)

art = read.table(text = "nbr     title     content
1       'title 1'   'This is an article about apple'
2       'title 2'   'This is an article about whirlpool'
3       'title 3'   'This is an article about samsung'
4       'title 4'   'This is an article about apple and samsung'
5       'title 5'   'This is an article about none of them'", header = T, stringsAsFactors = F)

如果您的供应商名称可能与其他单词混合，您可能需要在它们之前和之后添加单词边界 "\\b"，然后再将它们用作正则表达式模式。