[R] Help with read.csv.sql()

[H]

On 07/17/2020 09:49 PM, Bert Gunter wrote:
> Is there some reason that you can't make the changes to the data frame (column names, as.date(), ...) *after* you have read all your data in?
>
> Do all your csv files use the same names and date formats?
>
>
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along and sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>
>
> On Fri, Jul 17, 2020 at 6:28 PM H <agents using meddatainc.com <mailto:agents using meddatainc.com>> wrote:
>
>     I have created a dataframe with columns that are characters, integers and numeric and with column names assigned by me. I am using read.csv.sql() to read portions of a number of large csv files into this dataframe, each csv file having a header row with columb names.
>
>     The problem I am having is that the csv files have header rows with column names that are slightly different from the column names I have assigned in the dataframe and it seems that when I read the csv data into the dataframe, the column names from the csv file replace the column names I chose when creating the dataframe.
>
>     I have been unable to figure out if it is possible to assign column names of my choosing in the read.csv.sql() function? I have tried various variations but none seem to work. I tried colClasses = c(....) but that did not work, I tried field.types = c(...) but could not get that to work either.
>
>     It seems that the above should be feasible but I am missing something? Does anyone know?
>
>     A secondary issue is that the csv files have a column with a date in mm/dd/yyyy format that I would like to make into a Date type column in my dataframe. Again, I have been unable to find a way - if at all possible - to force a conversion into a Date format when importing into the dataframe. The best I have so far is to import is a character column and then use as.Date() to later force the conversion of the dataframe column.
>
>     Is it possible to do this when importing using read.csv.sql()?
>
>     ______________________________________________
>     R-help using r-project.org <mailto:R-help using r-project.org> mailing list -- To UNSUBSCRIBE and more, see
>     https://stat.ethz.ch/mailman/listinfo/r-help
>     PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>     and provide commented, minimal, self-contained, reproducible code.
>
Yes, the files use the same column names and date format (at least as far as I know now.) I agree I could do it as you suggest above but from a purist perspective I would rather do it when importing the data using read.csv.sql(), particularly if column names and/or date format might change, or be different between different files. I am indeed selecting rows from a large number of csv files so this is entirely plausible.

Has anyone been able to name columns in the read.csv.sql() call and/or force date format conversion in the call itself? The first refers to naming columns differently from what a header in the csv file may have.


	[[alternative HTML version deleted]]