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

[H]

On 07/18/2020 11:54 AM, Rui Barradas wrote:
> Hello,
>
> I don't believe that what you are asking for is possible but like Bert suggested, you can do it after reading in the data.
> You could write a convenience function to read the data, then change what you need to change.
> Then the function would return this final object.
>
> Rui Barradas
>
> Às 16:43 de 18/07/2020, H escreveu:
>
>> 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()?
>>>
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>>>      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]]
>>
>> ______________________________________________
>> 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.
>
The documentation for read.csv.sql() suggests that colClasses() and/or field.types() should work but I may well have misunderstood the documentation, hence my question in this group.