[R] Check for date variable in a arbitrary dataset

[Harsh]

Thank you Gabor for your prompt reply.

I had tried checking for class, but it returns three types of my
dataset, which are numeric, integer and character.
The problem with that is, I need to classify some columns as
categorical and in doing so I have a cut off of 100 or less unique
values in the column/variable.

In case of dates, I cannot consider it to be categorical, since in a
100,000 row dataset, dates will take more than 100 unique values, and
checking for its class will return character.
If i could somehow know it was a date, then I could provide a Time
Series analysis for it.
The same may hold true for, example serial number.

I tried using regexpr to check for the presence of "/" OR "-" to check
for it being a date column, but it returns the presence of the first
"/" which if is at the position 3, could mean a date format of
dd/mm/yyyy or mm/dd/yyyy.

This would be a long winded approach, and I am looking for something
more efficient.

Thank you for your time.


Harsh Singhal


On Mon, Nov 24, 2008 at 7:06 PM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> The classes of the columns are:
>
> sapply(DF, class)
>
>
> On Mon, Nov 24, 2008 at 3:39 AM, Harsh <singhalblr at gmail.com> wrote:
>> Hello,
>> This is my first time posting to the R-help list and I apologize for
>> the apparent triviality of my query.
>> I am creating an R script to create Univariate Exploratory Analysis of
>> a input dataset (No meta-data to provide extra information about each
>> column)
>> .
>> Providing summary statistics is possible in case of numeric data and
>> using all.is.numeric() from the Hmisc package allows me to filter out
>> those columns with alpha-numeric content.
>>
>> I have tried to check if a column is a date field or not, but have not
>> been able to do so. Are Regular Expressions the only answer? I've also
>> looked for CRAN packages but haven't found any.
>> Bering a newbie user of R, I do not possess the requisite knowledge to
>> write my own function for the above objective.
>>
>> Thank you for your time
>> Harsh
>> Decisions Systems Group
>> Mu Sigma Inc.
>> Chicago, IL
>>
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>>
>