如何使用列表中的名称创建新列 [英] How to create a new column with names in a list

问题描述

我已经在网上搜索帖子，以找到解决方案.但是，我什么也找不到.因此，我决定寻求您的帮助.我有一个带有数据框的列表.我从每个数据框中选择了某些列，并将它们组合在一起.当我合并来自两个数据帧的数据时，我想添加一列，其中包括列表的名称.但是，我无法实现这一目标.这是示例数据以及我尝试过的内容.

I have searched posts on web to find a solution. But, I could not identify any. Therefore, I decided to ask your help. I have a list with data frames. I chose certain columns from each data frame and combine them. When I was combining data from two data frames, I wanted to add a column which includes the names of the list. But, I could not achieve this. Here are a sample data and what I have tried.

样本数据和我的尝试

### 1st dataframe
time <- seq(as.Date("2014-09-01"), by = "day", length.out = 12)
temperature <- sample(c(15:26), replace = TRUE)
weather <- sample(c("clear", "cloudy", "rain"), size = 12, replace = TRUE)

rome <- data.frame(time, temperature, weather, stringsAsFactors = F)

### 2nd dataframe
time <- seq(as.Date("2014-09-01"), by = "day", length.out = 12)
temperature <- sample(c(12:23), replace = TRUE)
weather <- sample(c("clear", "cloudy", "rain"), size = 12, replace = TRUE)

paris <- data.frame(time, temperature, weather, stringsAsFactors = F)


### Assign names to each data frame and create a list
ana <- list(rome = rome, paris = paris)

#Here are a bit of data.

#> ana
#$rome
#         time temperature weather
#1  2014-09-01          19  cloudy
#2  2014-09-02          21  cloudy
#3  2014-09-03          17   clear

#$paris
#         time temperature weather
#1  2014-09-01          18   clear
#2  2014-09-02          12  cloudy
#3  2014-09-03          17  cloudy

### Select 1st and 2nd column from each data frame in the list and 
### combine them.

rbind.fill(lapply(ana, `[`, 1:2))

我想在此处添加一些内容，以便使用新列(位置)创建以下理想结果.请注意，我修剪了理想的结果以节省空间.

I wanted to add something here to create the following ideal outcome with the new column, location. Please note that I trimmed the ideal outcome to save space.

         time temperature location
1  2014-09-01          19     rome
2  2014-09-02          21     rome
3  2014-09-03          17     rome
13 2014-09-01          18    paris
14 2014-09-02          12    paris
15 2014-09-03          17    paris

我尝试过的一件事是以下面的方式使用cbind()，尽管我知道这是行不通的.

One thing I tried was to use cbind() in the following way although I knew this would not work.

lapply(ana, function(x) cbind(x, new = names(ana)))

#$rome
#         time temperature   new
#1  2014-09-01          19  rome
#2  2014-09-02          21 paris
#3  2014-09-03          17  rome
#
#$paris
#         time temperature   new
#1  2014-09-01          18  rome
#2  2014-09-02          12 paris
#3  2014-09-03          17  rome

我觉得setNames()可以提供某些东西，并且可以通过简单的方式完成.我可能是错的.非常感谢您抽出宝贵的时间.

I have the feeling that setNames() may offer something, and that this can be done in a simple way. I could be wrong, though. Thank you very much for taking your time.

推荐答案

您可以

ana <- Map(cbind, ana, location = names(ana))

在调用rbind.fill之前附加location列.

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