[R] Count number of Fridays in a month

[Duncan Murdoch]

On 10/10/2014 8:10 AM, Abhinaba Roy wrote:
> Hi Duncan,
>
> I have converted the string to a POSIXIt object using
>
> > strptime('31-may-2014',format="%d-%b-%Y")
>
> But could not figure out the way forward.
>
> Could you please elaborate a bit?

Try this:

?POSIXlt

Duncan Murdoch

>
> On Fri, Oct 10, 2014 at 5:14 PM, Duncan Murdoch 
> <murdoch.duncan at gmail.com <mailto:murdoch.duncan at gmail.com>> wrote:
>
>     On 10/10/2014, 7:28 AM, Abhinaba Roy wrote:
>     > Hi R helpers,
>     >
>     > I want to write a function which will
>     >
>     > 1. Count the number of fridays in the current month ( to extract
>     month from
>     > given date) and also the number of fridays in the preceeding month
>     >
>     > 2. Calculate the ratio of the number of fridays in current month
>     to the
>     > number of fridays in the precceding month
>     >
>     > 3. Return a integer value calculated as
>     >     ifelse(ratio>1,1,ifesle(ration<1,-1),0)
>     >
>     > The date which is passed is in the format *'31-may-2014'*
>     >
>     > So, given the date '31-may-2014'
>     >
>     > Number of fridays in May2014 = 5
>     > Number of fridays in Apr2014 = 4
>     >
>     > Ratio = 5/4 >1
>     > Hence, the function will return a value 1
>     >
>     > I want to call the function by passing '31-may-2014' as an argument
>     >
>     > How can this be done in R?
>     >
>     > Any help will be appreciated
>
>     Convert your string to a POSIXlt object using as.POSIXlt.  Then
>     you can
>     extract year, month and weekday from the result, and go from there.
>     (The only unobvious part is figuring out how many days are in each
>     month, but there are questions online giving various ways to do this.)
>
>     Duncan Murdoch
>
>