R-通过遍历向量中的元素将列添加到列表中的数据框 [英] R - Add columns to dataframes in list by looping through elements in a vector

问题描述

我正在使用多个数据集，这些数据集多年来测量了相同的变量.我正在尝试为每个数据集添加year变量，但更一般而言，我想遍历向量中的元素，并将每个元素添加为数据帧列表中的新列.这个问题类似于我的问题，但我想将向量中的每个元素作为新列迭代添加到相应的数据帧中: R-跨多个数据帧的新变量循环

I am working with several datasets that measure the same variables over many years. I am trying to add a year variable to each dataset, but more generally I want to loop through elements in a vector and add each as a new column in a list of dataframes. This question was similar to mine but I want to iteratively add each element in a vector to the corresponding dataframe as a new column: R - New variables over several data frames in a loop

以下是示例数据:

year <- c(1:3)
data1 <- data.frame(var1 = c(1:5))
data2 <- data.frame(var1 = c(11:15))
data3 <- data.frame(var1 = c(21:25))
data_list <- list(data1 = data1, data2 = data2, data3 = data3)

我想这样做，但是认为可能还有一些我还无法弄清楚的循环方式(或不适当地适用):

I want to do this but think there's probably some way to loop (or lapply) that I haven't been able to figure out yet:

data1$year <- year[1]
data2$year <- year[2]
data3$year <- year[3]

由于我有多年的工作经验和数据集，因此拥有一个更有效的解决方案将是很棒的.谢谢！

Since I have many years and datasets to work with, it'd be great to have a more efficient solution. Thanks!

推荐答案

基于@@ thelatemail评论的完整答案:

The full answer based on @@thelatemail comment:

函数 Map(cbind，data_list，year = year)应该可以完成这项工作.逐步:

The function Map(cbind, data_list, year=year) should do the job. Step by step:

• Map 函数指示列表中元素的循环
• cbind 附加新创建的列
• year = years 根据向量 years
中的元素创建一个名为 year 的新列.

• Map function indicates a loop through elements in a list
• cbind attaches newly created column
• year = years creates new column named year based on elements in a vector years

有一个虚拟的例子:

# vector of values you wish to add
years <- c(1:3)     # changed to plural to indicate vector of values rather than single value

# make dummy list of dataframes
data1 <- data.frame(var1 = c(1:5))
data2 <- data.frame(var1 = c(11:15))
data3 <- data.frame(var1 = c(21:25))
data_list <- list(data1 = data1, data2 = data2, data3 = data3)

# Loop through list of dataframes and to each dataframe add a new column
Map(cbind, data_list, year=years)

您想要的输出:

$`data1`
  var1 year
1    1    1
2    2    1
3    3    1
4    4    1
5    5    1

$data2
  var1 year
1   11    2
2   12    2
3   13    2
4   14    2
5   15    2

$data3
  var1 year
1   21    3
2   22    3
3   23    3
4   24    3
5   25    3

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