使用货币列作为数字读取R中的csv文件 [英] Read csv file in R with currency column as numeric

问题描述

我正在尝试将包含政治捐款信息的csv文件读入R。据我了解，默认情况下这些列是作为因素导入的，但是我需要将数量列（数据集中的 CTRIB_AMT）作为数值列导入，以便我可以运行各种不适用于的功能因素。该列的格式为货币，前缀为 $。

I'm trying to read into R a csv file that contains information on political contributions. From what I understand, the columns by default are imported as factors, but I need the the amount column ('CTRIB_AMT' in the dataset) to be imported as a numeric column so I can run a variety of functions that wouldn't work for factors. The column is formatted as a currency with a "$" as prefix.

我最初使用简单的读取命令导入文件：

I used a simple read command to import the file initially:

contribs <- read.csv('path/to/file')

，然后尝试将CTRIB_AMT从货币转换为数字：

And then tried to convert the CTRIB_AMT from currency to numeric:

as.numeric(as.character(sub("$","",contribs$CTRIB_AMT, fixed=TRUE)))

但是那没有用。我要用于CTRIB_AMT列的函数是：

But that didn't work. The functions I'm trying to use for the CTRIB_AMT columns are:

vals<-sort(unique(dfr$CTRIB_AMT))
sums<-tapply( dfr$CTRIB_AMT, dfr$CTRIB_AMT, sum)
counts<-tapply( dfr$CTRIB_AMT, dfr$CTRIB_AMT, length)

请参阅相关问题此处。

是否有任何关于如何最初导入文件，列为数字或在导入后如何转换的想法？

Any thoughts on how to import file initially so column is numeric or how to convert it after importing?

推荐答案

我不确定如何直接读取它，但是一旦它位于其中就可以对其进行修改：

I'm not sure how to read it in directly, but you can modify it once it's in:

> A <- read.csv("~/Desktop/data.csv")
> A
  id   desc price
1  0  apple $1.00
2  1 banana $2.25
3  2 grapes $1.97
> A$price <- as.numeric(sub("\\$","", A$price))
> A
  id   desc price
1  0  apple  1.00
2  1 banana  2.25
3  2 grapes  1.97
> str(A)
'data.frame':   3 obs. of  3 variables:
 $ id   : int  0 1 2
 $ desc : Factor w/ 3 levels "apple","banana",..: 1 2 3
 $ price: num  1 2.25 1.97

我认为这可能只是您的子程序中缺少的转义符。 $表示正则表达式中的行尾。 \ $是美元符号。但是然后您必须逃脱……

I think it might just have been a missing escape in your sub. $ indicates the end of a line in regular expressions. \$ is a dollar sign. But then you have to escape the escape...

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