Question

我试图弄清楚如何使用一些分隔符将多个列粘贴在一起，但我想将这些列组合在一起，比如说2.例如，我有一个数据帧{{1}如下：

df

我想分别合并df <- data.frame(matrix(ncol = 4, nrow = 3)) x <- c("a", "b", "c", "d") colnames(df) <- x df$a <- c("man", "bear", "pig") df$b <- c("chicken", "moose", "bear") df$c <- c("fish", "dog", "bear") df$d <- c("dog", "mouse", "moose") df # a b c d #1 man chicken fish dog #2 bear moose dog mouse #3 pig bear bear moose和a + b列。我可以通过以下步骤将它粘贴在一起来实现它：

c + d

但我真的想坚持DRY原则来获得更清晰的代码。我尝试用df$combined1 <- paste(df$a, df$b, sep = " + ") df$combined2 <- paste(df$c, df$d, sep = " + ")做，但没有运气。有什么想法吗？

感谢您的帮助！

Answer 1

首先，本着可读性的精神，让我们简化您的数据创建代码。绝对不需要所有这些中间变量：

df <- data.frame(
    a = c("man", "bear", "pig"),
    b = c("chicken", "moose", "bear"),
    c = c("fish", "dog", "bear"),
    d = c("dog", "mouse", "moose")
)

现在回答你的问题。这很一般。首先，我们定义要组合的列的列表，然后我们将它们组合在一起，创建组合列的名称，并仅通过引用数据和组合列表来组合它们：

cols_to_combine = list(c(1, 2), c(3, 4))

for (comb in cols_to_combine) {
    df[[paste0("combined_", paste(comb, collapse = "_"))]] =
        do.call(paste, args = c(df[comb], sep = " + "))
}

df
#      a       b    c     d  combined_1_2 combined_3_4
# 1  man chicken fish   dog man + chicken   fish + dog
# 2 bear   moose  dog mouse  bear + moose  dog + mouse
# 3  pig    bear bear moose    pig + bear bear + moose

如何批量粘贴列

1 个答案: