Question

我开始学习R并且我得到了循环错误。

这是我得到的错误：

Error in names(data1)[5] <- "TR" : 
'names' attribute [5] must be the same length as the vector [4]

这是我的代码：

#read data
data1<-read.table("C_0.txt",header = T,sep=",")

#name the 5th col TR
names(data1)[5]<-"TR"

#calculate the length of data1
n<-nrow(data1)

#initialize first TR value to NA
data1[1,5]<-NA

for (i in 1:(n-1)){

if (data1[i,3]==data1[i+1,3]) {data1[i+1,5]<-data1[i,5]}

if (data1[i,3]< data1[i+1,3]) {data1[i+1,5]<- 1}

if(data1[i,3]> data1[i+1,3]) {data1[i+1,5]<- -1}
}

这是我想编写的算法：如果当前价格高于之前的价格，则在名为TR的列中标记+1 如果当前价格低于先前价格，则在名为TR的列中标记为-1 如果当前价格与之前的价格相同，则在名为TR

的列中标记与之前价格相同的价格

我将第一个TR行标记为NA，因为没有价格与之比较。

这里是来自C_0.txt的数据：

Date,Time,Price,Size
02/18/2014,05:06:13,49.6,200
02/18/2014,05:06:13,49.6,200
02/18/2014,05:06:13,49.6,200
02/18/2014,05:06:14,49.6,200
02/18/2014,05:06:14,49.6,193
02/18/2014,05:44:41,49.62,100
02/18/2014,06:26:36,49.52,100
02/18/2014,06:26:36,49.52,500
02/18/2014,07:09:29,49.6,100
02/18/2014,07:56:40,49.56,300
02/18/2014,07:56:40,49.55,400
02/18/2014,07:56:41,49.54,200
02/18/2014,07:56:43,49.55,100
02/18/2014,07:56:43,49.55,100
02/18/2014,07:56:50,49.55,100
02/18/2014,07:57:12,49.53,100
02/18/2014,07:57:12,49.51,2200
02/18/2014,07:57:12,49.51,100
02/18/2014,07:57:12,49.5,200

非常感谢！

Answer 1

向数据框添加列是相当基本的东西。这是一个总结了这个问题的问题。

您无法通过更改名称属性向量的长度来向数据框添加列。您必须通过this question中的方法创建它。

至于问题的其他部分，我们使用diff和rle代替for-loop。

d <-  read.table(sep = ",", text = 
"Date,Time,Price,Size
02/18/2014,05:06:13,49.6,200
02/18/2014,05:06:13,49.6,200
02/18/2014,05:06:13,49.6,200
02/18/2014,05:06:14,49.6,200
02/18/2014,05:06:14,49.6,193
02/18/2014,05:44:41,49.62,100
02/18/2014,06:26:36,49.52,100
02/18/2014,06:26:36,49.52,500
02/18/2014,07:09:29,49.6,100
02/18/2014,07:56:40,49.56,300
02/18/2014,07:56:40,49.55,400
02/18/2014,07:56:41,49.54,200
02/18/2014,07:56:43,49.55,100
02/18/2014,07:56:43,49.55,100
02/18/2014,07:56:50,49.55,100
02/18/2014,07:57:12,49.53,100
02/18/2014,07:57:12,49.51,2200
02/18/2014,07:57:12,49.51,100
02/18/2014,07:57:12,49.5,200", header = TRUE)

tmp <- c(NA, diff(d$Price))
tmp <- sign(tmp)
tmp <- rle(tmp)
l <- tmp$lengths
v <- tmp$values
idx <- which(v == 0L)
l[idx - 1] <- l[idx - 1] + l[idx]
l <- l[-idx]
v <- v[-idx]
d$TR <- inverse.rle(list(lengths = l, values = v))

#          Date     Time Price Size TR
# 1  02/18/2014 05:06:13 49.60  200 NA
# 2  02/18/2014 05:06:13 49.60  200 NA
# 3  02/18/2014 05:06:13 49.60  200 NA
# 4  02/18/2014 05:06:14 49.60  200 NA
# 5  02/18/2014 05:06:14 49.60  193 NA
# 6  02/18/2014 05:44:41 49.62  100  1
# 7  02/18/2014 06:26:36 49.52  100 -1
# 8  02/18/2014 06:26:36 49.52  500 -1
# 9  02/18/2014 07:09:29 49.60  100  1
# 10 02/18/2014 07:56:40 49.56  300 -1
# 11 02/18/2014 07:56:40 49.55  400 -1
# 12 02/18/2014 07:56:41 49.54  200 -1
# 13 02/18/2014 07:56:43 49.55  100  1
# 14 02/18/2014 07:56:43 49.55  100  1
# 15 02/18/2014 07:56:50 49.55  100  1
# 16 02/18/2014 07:57:12 49.53  100 -1
# 17 02/18/2014 07:57:12 49.51 2200 -1
# 18 02/18/2014 07:57:12 49.51  100 -1
# 19 02/18/2014 07:57:12 49.50  200 -1

R：错误：向量在for循环中的长度不同

1 个答案: