Changing month name and year to date or POSIXct

Question

I have a data frame

             date     df discharge cfs   green discharge cfs   north discharge cfs
1   December 2018        2520.1394           171.69667             


        

Answer 1

In base R, we can paste an arbitrary date , convert to date object and then format

format(as.Date(paste0('1', df$date), '%d %B %Y'), '%m-%Y')

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Another option with regex and using an inbuilt vector month.name can be

with(df, paste(match(sub('\\s\\d+', '', date), month.name), 
                     sub('.*\\s+', '', df$date), sep = '-'))