在整个数据框中查找多个字符串 [英] Find multiple strings in entire dataframe

问题描述

我正在尝试使用which函数在数据框中找到多个字符串。我正在尝试从在data.frame中查找字符串

I am trying to find multiple strings in my dataframe, using the which function. I am trying to extend the answer from Find string in data.frame

示例数据帧为：

df1 <-data.frame（animal = c（' a'，'b'，'c'，'两个'，'五个'，'c'），level = c（'五个'，'一个'，'三个'，30，'马'，'五个'） ，length = c（10，20，30，'horse'，'eight'，'c'））

1      a  five     10
2      b   one     20
3      c three     30
4    two    30  horse
5   five horse  eight
6      c  five      c 

我得到正确的输出，例如
which（df1 == c，arr.ind = T）; df1
给出：

on this dataframe when I apply the which function for one string, I get the correct output e.g. which(df1 =="c" , arr.ind = T);df1 gives:

  row col
[1,]   3   1
[2,]   6   1
[3,]   6   3

但是当我尝试搜索多个字符串时，我只会得到部分正确的输出，例如
which（df1 == c（ c， horse，五个），arr.ind = T）

But when I try to search for multiple strings, I get only a partially correct output e.g. which(df1 ==c("c", "horse", "five") , arr.ind = T)

  row col
[1,]   5   2
[2,]   6   2

预期输出应为：

     row col
[1,]   3   1
[2,]   5   1
[3,]   6   1
[4,]   1   2
[5,]   5   2
[6,]   6   2
[7,]   4   3
[8,]   6   3

因此我的问题：

1. 为什么用c（ c，马，五个）不起作用？

1. why does the solution with c("c", "horse", "five") not work?

我尝试过

which（df1 == c | df1 == horse | df1 == five，arr.ind = T）

这可以给我正确的输出，但是对于许多字符串来说，太长了，
如何使我的代码简洁？

that gives me the correct output, but for many strings is too lengthy, how can I make my code succinct?

推荐答案

我们可以使用 lapply 遍历向量，执行 == ，减少并用 | 并用 which

We can loop through the vector with lapply, do the ==, Reduce it to single logical matrix with | and wrap with which

which(Reduce(`|`, lapply(c("c", "horse", "five"), `==`, df1)), arr.ind = TRUE)
#     row col
#[1,]   3   1
#[2,]   5   1
#[3,]   6   1
#[4,]   1   2
#[5,]   5   2
#[6,]   6   2
#[7,]   4   3
#[8,]   6   3

---

或者另一个选择是使用 mutate_all 遍历数据集的列并使用<$包装c $ c>其中

---

Or another option would be to loop through the columns of dataset with mutate_all and wrap with which

library(dplyr)
df1 %>%
  mutate_all(list(~ . %in% c("c", "horse", "five"))) %>%
  as.matrix %>% 
  which(., arr.ind = TRUE)

注意：在这里，如果OP想要做一个完整的字符串，我们不需要任何正则表达式或部分匹配项比赛。通常应该比进行部分匹配要快

NOTE: Here, we don't need any regex or partial matches if the OP wanted to do a full string match. It should be faster than doing any partial matches

通常，对于多个元素％in％会很有用，但是它仅适用于向量而不适用于data.frame

Usually, for multiple elements %in% would be useful, but, it works only on a vector and not a data.frame

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