如何使用 tidyr::unite 函数删除 NA? [英] How do I remove NAs with the tidyr::unite function?

问题描述

在将几列与 tidyr::unite() 合并后，丢失数据中的 NA 保留在我不想要的字符向量中.

After combining several columns with tidyr::unite(), NAs from missing data remain in my character vector, which I do not want.

我每行有一系列医疗诊断(每列 1 个)，并希望对一系列代码进行基准搜索via. %in% 和 grepl().

I have a series of medical diagnoses per row (1 per column) and would like to benchmark searching for a series of codes via. %in% and grepl().

Github 上有一个关于这个问题的公开问题，有没有动静- 或变通?我想保持矢量逗号分隔.

There is an open issue on Github on this problem, is there any movement - or work arounds? I would like to keep the vector comma-separated.

这是一个代表性的例子:

Here is a representative example:

library(dplyr)
library(tidyr)

df <- data_frame(a = paste0("A.", rep(1, 3)), b = " ", c = c("C.1", "C.3", " "), d = "D.4", e = "E.5")

cols <- letters[2:4]
df[, cols] <- gsub(" ", NA_character_, as.matrix(df[, cols]))
tidyr::unite(df, new, cols, sep = ",")

当前输出:

# # A tibble: 3 x 3
#   a     new        e    
#   <chr> <chr>      <chr>
# 1 A.1   NA,C.1,D.4 E.5  
# 2 A.1   NA,C.3,D.4 E.5  
# 3 A.1   NA,NA,D.4  E.5 

所需的输出:

# # A tibble: 3 x 3
#   a     new        e    
#   <chr> <chr>      <chr>
# 1 A.1   C.1,D.4    E.5  
# 2 A.1   C.3,D.4    E.5  
# 3 A.1   D.4        E.5 

推荐答案

您可以在创建 NA 后使用正则表达式删除它们:

You could use regex to remove the NAs after they are created:

library(dplyr)
library(tidyr)

df <- data_frame(a = paste0("A.", rep(1, 3)), 
                 b = " ", 
                 c = c("C.1", "C.3", " "), 
                 d = "D.4", e = "E.5")

cols <- letters[2:4]
df[, cols] <- gsub(" ", NA_character_, as.matrix(df[, cols]))
tidyr::unite(df, new, cols, sep = ",") %>% 
     dplyr::mutate(new = stringr::str_replace_all(new, 'NA,?', ''))  # New line

输出:

# A tibble: 3 x 3
  a     new     e    
  <chr> <chr>   <chr>
1 A.1   C.1,D.4 E.5  
2 A.1   C.3,D.4 E.5  
3 A.1   D.4     E.5  

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