将长字符串转换为data.frame

Question

这是一个noob问题，但我对此感到疯狂。我有一个名为bars.list的角色矢量，我从FTP服务器下载。矢量看起来是这样的：

"\"\",\"times\",\"open\",\"high\",\"low\",\"close\",\"numEvents\",\"volume\"\r\n\"1\",2015-05-18 06:50:00,23.98,23.98,23.5,23.77,421,0\r\n\"2\",2015-05-18 07:50:00,23.77,23.9,23.34,23.6,720,0\r\n\"3\",2015-05-18 08:50:00,23.6,23.6,23.32,23.42,720,0\r\n\"4\",2015-05-18 09:50:00,23.44,23.91,23.43,23.66,720,0\r\n\"5\",2015-05-18 10:50:00,23.67,24.06,23.59,24.02,720,0\r\n\"6\",2015-05-18 11:50:00,24.02,24.04,23.32,23.33,720,0\r\n\"7\",2015-05-18 12:50:00,23.33,23.42,22.74,22.81,720,0\r\n\"8\",2015-05-18 13:50:00,22.79,22.92,22.49,22.69,720,0\r\n\"9\",2015-05-18 14:50:00,22.69,22.7,22.14,22.14,481,0\r\n\"10\",2015-05-19 06:50:00,21.09,21.49,20.82,21.47,421,0\r\n\"11\",2015-05-19 07:50:00,21.48,21.68,21.46,21.51,720,0\r\n\"12\",2015-05-19 08:50:00,21.51,21.93,21.45,21.92,720,0\r\n\"13\",2015-05-19 09:50:00,21.92,21.92,21.55,21.55,720,0\r\n\" 

我需要这个载体转换成可用的格式，但

> read.table(bars.list, header = TRUE, sep = ",", quote = "", dec = ".") 
Error in file(file, "rt") : cannot open the connection 
In addition: Warning message: 
In file(file, "rt") : 
    cannot open file '"","times","open","high","low","close","numEvents","volume" 
"1",2015-05-18 06:50:00,23.98,23.98,23.5,23.77,421,0 
"2",2015-05-18 07:50:00,23.77,23.9,23.34,23.6,720,0 
"3",2015-05-18 08:50:00,23.6,23.6,23.32,23.42,720,0 
"4",2015-05-18 09:50:00,23.44,23.91,23.43,23.66,720,0 

为什么[R告诉我，一些连接无法打开的对象，是我不太清楚已经被粘贴为该函数的参数。输出R显示我的警告标志已经非常接近我所需...

Answer 1

这里有两个选项。第一个提供了一个修复你当前的代码，第二个看起来更简单更有效的选择。

选项1：read.table()的第一个参数是file。您正在从矢量中读取而不是从文件读取，因此您需要使用text参数，并使用text = bars.list。

另外，我们可以摆脱所有的报价与gsub()，然后再使用 read.csv()代替read.table()因为header = TRUE和sep = ","是默认值出现。

read.csv(text = gsub("\"", "", bars.list), row.names = 1) 
#     times open high low close numEvents volume 
# 1 2015-05-18 06:50:00 23.98 23.98 23.50 23.77  421  0 
# 2 2015-05-18 07:50:00 23.77 23.90 23.34 23.60  720  0 
# 3 2015-05-18 08:50:00 23.60 23.60 23.32 23.42  720  0 
# 4 2015-05-18 09:50:00 23.44 23.91 23.43 23.66  720  0 
# 5 2015-05-18 10:50:00 23.67 24.06 23.59 24.02  720  0 
# 6 2015-05-18 11:50:00 24.02 24.04 23.32 23.33  720  0 
# 7 2015-05-18 12:50:00 23.33 23.42 22.74 22.81  720  0 
# 8 2015-05-18 13:50:00 22.79 22.92 22.49 22.69  720  0 
# 9 2015-05-18 14:50:00 22.69 22.70 22.14 22.14  481  0 
# 10 2015-05-19 06:50:00 21.09 21.49 20.82 21.47  421  0 
# 11 2015-05-19 07:50:00 21.48 21.68 21.46 21.51  720  0 
# 12 2015-05-19 08:50:00 21.51 21.93 21.45 21.92  720  0 
# 13 2015-05-19 09:50:00 21.92 21.92 21.55 21.55  720  0 

对我来说，这个工作比read.csv()使用quote参数更好。

选项2：从data.table包fread()很好地工作过。它速度更快，代码更干净。无需使用gsub()。我们可以直接放入bars.list并放置第一列。

data.table::fread(bars.list, drop = 1) 

现在，由于最终的\"报价，您将收到此方法的警告。您可以通过移除最后一个引号来获得无警告的结果。

data.table::fread(sub("\"$", "", bars.list), drop = 1) 

数据：

bars.list <- "\"\",\"times\",\"open\",\"high\",\"low\",\"close\",\"numEvents\",\"volume\"\r\n\"1\",2015-05-18 06:50:00,23.98,23.98,23.5,23.77,421,0\r\n\"2\",2015-05-18 07:50:00,23.77,23.9,23.34,23.6,720,0\r\n\"3\",2015-05-18 08:50:00,23.6,23.6,23.32,23.42,720,0\r\n\"4\",2015-05-18 09:50:00,23.44,23.91,23.43,23.66,720,0\r\n\"5\",2015-05-18 10:50:00,23.67,24.06,23.59,24.02,720,0\r\n\"6\",2015-05-18 11:50:00,24.02,24.04,23.32,23.33,720,0\r\n\"7\",2015-05-18 12:50:00,23.33,23.42,22.74,22.81,720,0\r\n\"8\",2015-05-18 13:50:00,22.79,22.92,22.49,22.69,720,0\r\n\"9\",2015-05-18 14:50:00,22.69,22.7,22.14,22.14,481,0\r\n\"10\",2015-05-19 06:50:00,21.09,21.49,20.82,21.47,421,0\r\n\"11\",2015-05-19 07:50:00,21.48,21.68,21.46,21.51,720,0\r\n\"12\",2015-05-19 08:50:00,21.51,21.93,21.45,21.92,720,0\r\n\"13\",2015-05-19 09:50:00,21.92,21.92,21.55,21.55,720,0\r\n\""