Importing csv file into R - numeric values read as characters

Question

I am aware that there are similar questions on this site, however, none of them seem to answer my question sufficiently.

This is what I have done so far:

I have a csv file which I open in excel. I manipulate the columns algebraically to obtain a new column "A". I import the file into R using read.csv() and the entries in column A are stored as factors - I want them to be stored as numeric. I find this question on the topic:

Imported a csv-dataset to R but the values becomes factors

Following the advice, I include stringsAsFactors = FALSE as an argument in read.csv(), however, as Hong Ooi suggested in the page linked above, this doesn't cause the entries in column A to be stored as numeric values.

A possible solution is to use the advice given in the following page:

How to convert a factor to an integer umeric without a loss of information?

however, I would like a cleaner solution i.e. a way to import the file so that the entries of column entries are stored as numeric values.

Cheers for any help!

Answer 1

Whatever algebra you are doing in Excel to create the new column could probably be done more effectively in R.

Please try the following: Read the raw file (before any excel manipulation) into R using read.csv(... stringsAsFactors=FALSE). [If that does not work, please take a look at ?read.table (which read.csv wraps), however there may be some other underlying issue].

For example:

   delim = ","  # or is it "" ?
   dec = "."    # or is it "," ?
   myDataFrame <- read.csv("path/to/file.csv", header=TRUE, sep=delim, dec=dec, stringsAsFactors=FALSE)

Then, let's say your numeric columns is column 4

   myDataFrame[, 4]  <- as.numeric(myDataFrame[, 4])  # you can also refer to the column by "itsName"

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Lastly, if you need any help with accomplishing in R the same tasks that you've done in Excel, there are plenty of folks here who would be happy to help you out