Question

我想一次读取许多csv文件到一个大的哈希结构，其中键下面（将是csv文件的名称）可以访问特定的数据集。 AFAIK R没有哈希值，因此选择使用带有命名元素的列表（如果这不正确的方法请纠正我）。到目前为止我的代码：

csv_files <- list.files(pattern="*.csv");
datasets  <- vector("list", length(csv_files));
names(datasets) <- csv_files;

for (i in 1:length(datasets)){
  csv_file <- names(datasets[i])
  datasets[i] <- read.csv(file=csv_file, header=T, sep=",", skip=0, check.names=TRUE)
}

但是这段代码不起作用（datasets包含其他内容但不包含特定的csv data.frame）并返回以下警告：

Warning messages:
1: In datasets[i] <- read.csv(file = csv_file, header = T, sep = ",",  :
  number of items to replace is not a multiple of replacement length
2: In datasets[i] <- read.csv(file = csv_file, header = T, sep = ",",  :
  number of items to replace is not a multiple of replacement length
3: In datasets[i] <- read.csv(file = csv_file, header = T, sep = ",",  :
  number of items to replace is not a multiple of replacement length
4: In datasets[i] <- read.csv(file = csv_file, header = T, sep = ",",  :
  number of items to replace is not a multiple of replacement length
5: In datasets[i] <- read.csv(file = csv_file, header = T, sep = ",",  :
  number of items to replace is not a multiple of replacement length

以下是我的问题排查结果：

似乎从csv文件中读取文件正在运行：

> csv_file <- names(datasets[1])
> temp_dataset <- read.csv(file=csv_file, header=T, sep=",", skip=0, check.names=TRUE)
> temp_dataset
   ord orig pred as o.p
1    1    0    0  1   0
2    2    0    0  1   0
3    3    0    0  1   0
4    4    0    0  0   0
5    5    0    0  0   0
6    6    0    0  0   0
7    7    0    0  0   0
8    8    0    0  0   0
9    9    0    0  0   0
10  10    0    0  0   0
11  11    0    0  0   0
12  12    0    0  0   0
13  13    0    0  0   0
14  14    0    0  0   0
15  15    0    0  0   0
16  16    0    0  0   0
17  17    0    0  0   0
18  18    0    0  0   0
19  19    0    0  0   0
20  20    0    0  0   0
21  21    0    0  0   0
22  22    0    0  0   0
23  23    4    0  0   4
24  24  402    0  1 402
25  25    0    0  1   0
26  26    0    0  1   0
27  27    0    0  1   0
28  28    1    0  1   0

问题在于将这些数据分配给列表中的特定数据框

> datasets[1] <- temp_dataset[-1]
Warning message:
In datasets[1] <- temp_dataset[-1] :
  number of items to replace is not a multiple of replacement length

似乎只有第一列被分配给列表中的特定数据框：

> datasets[1]
$repeating.csv
repeating.csv
 [1]   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0
[17]   0   0   0   0   0   0   4 402   0   0   0   1

我缺少什么？

Answer 1

基于@RichardScriven，@ joran评论我最终得到了以下解决方案：

CSV_PATH="/home/wakatana/r/csv"
CSV_FILES <- list.files(pattern="*.csv");
DATASETS  <- vector("list", length(CSV_FILES))
names(DATASETS) <- CSV_FILES
for (i in 1:length(CSV_FILES)){
  message(CSV_FILES[i])
  full.csv.path = file.path(CSV_PATH, CSV_FILES[i])
  if (CSV_FILES[i] == "skip_first_four_lines.csv"){
    DATASETS[[i]] <- read.csv(file=full.csv.path, header=F, sep=",", skip=4, col.names = names(read.csv(file=full.csv.path, nrow = 0)))
  }
  else {
    DATASETS[[i]] <- read.csv(file=full.csv.path, header=T, sep=",", skip=0, check.names=TRUE)
  }
}

如果有人会表现出不同的方法并解释为什么会更好，我会接受他的问题。

从csv文件

1 个答案: