合并多列，排除空值 [英] Combine multiple columns, excluding null values

问题描述

我正在尝试找出如何组合多列（不包括NA值）。

I'm trying to figure out how to combine multiple columns, excluding NA values.

输入数据框：

data <- data.frame(
  id = c(1:3),
  Item1 = c("Egg", "", ""),
  Item2 = c("Chicken", "Flour", ""),
  Item3 = c("", "", "Bread"),
  Item4 = c("", "Milk", "")
)

所需数据框：

desired <- data.frame(
  id = c(1:3),
  Item1 = c("Egg", "", ""),
  Item2 = c("Chicken", "Flour", ""),
  Item3 = c("", "", "Bread"),
  Item4 = c("", "Milk", ""),
  Combine = c("Egg, Chicken", "Flour, Milk", "Bread")
)

我尝试使用以下代码组合值：

I have tried combining the values using the following code:

data$Combine = paste(data$Item1, data$Item2, data$Item3, data$Item4, sep=",")

问题是我得到这样的结果：

The issue is that I'm getting results like this:

蛋icken ,,

，面粉,,牛奶

,,面包

Egg,Chicken,,
,Flour,,Milk
,,Bread,

推荐答案

如果我们使用与OP中类似的方法，请用 替换前导/滞后空格，并重复不止一个空格，和单个，使用 gsub

If we use the similar approach as in the OP's post, replace the leading/lagging spaces with "" and those having more than one repeating , with a single , using gsub

data$Combine <- gsub(",{2,}", ",", 
       gsub("^,+|,+$", "", do.call(paste, c(data[-1], sep=","))))
data$Combine
#[1] "Egg,Chicken" "Flour,Milk"  "Bread"

---

或者另一种选择是使用粘贴，删除前导/滞后空格（修剪），然后替换一个或多个空格（ \\s + ）和，使用 gsub

---

Or another option is to use paste, remove the leading/lagging spaces (trimws) and then replace one or more spaces (\\s+) with a , using gsub

gsub("\\s+", ",", trimws(do.call(paste,  data[-1])))
#[1] "Egg,Chicken" "Flour,Milk"  "Bread"  

data

data

data <- structure(list(ID = 1:3, Item1 = c("Egg", "", ""), Item2 = c("Chicken", 
"Flour", ""), Item3 = c("", "", "Bread"), Item4 = c("", "Milk", 
"")), .Names = c("ID", "Item1", "Item2", "Item3", "Item4"),
class = "data.frame", row.names = c(NA, -3L))

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