Month name to value in Julia? - julia

Question

I need to convert a peculiar format of textual dates into dates in Julia. I found out about the MONTHTOVALUE dictionary in the Dates documentation, but this object is missing from the Dates namespace, gives no results in the help, and only appears in the Github source code in the documentation. I used Date.format() with formatting "U" to define my own MONTHTOVALUE:
# Build dictionary from month names to integers
MONTHTOVALUE = Dict{String, Integer}()
for i in 1:12
month = Dates.format(Date(1990, i, 1), "U")
MONTHTOVALUE[month] = i
end;
# Regular expression for date in the format [Month Year(Quarter)]
date_regex = r"(^[A-Z][a-z]*) ?(\d{4}) ?\((I*V?)\)";
function string_to_date(date_string)
month = MONTHTOVALUE[replace(date_string, date_regex, s"\1")]
year = parse(Int, replace(date_string, date_regex, s"\2"))
return Dates.Date(year, month, 1)
end;
#assert Dates.Date(1860, 10, 1) == string_to_date("October 1860(III)")
Does the MONTHTOVALUE dictionary exist already, or do you suggest a cleaner way?

Answer 1

If I understand the question correctly, you wish to access the dictionary inside the Dates module that maps month names to their number ("March"=>3, etc.), is that correct?
If so, Dates.LOCALES["english"].month_value seems to be the one you're looking for:
julia> Dates.LOCALES["english"].month_value
Dict{String,Int64} with 24 entries:
"January" => 1
"august" => 8
"May" => 5
"may" => 5
"December" => 12
"january" => 1
"August" => 8
"november" => 11
"december" => 12
"September" => 9
"july" => 7
"september" => 9
"October" => 10
"june" => 6
"November" => 11
"April" => 4
"February" => 2
"october" => 10
"March" => 3
"June" => 6
"april" => 4
"march" => 3
"february" => 2
"July" => 7
(There's also a Dates.LOCALES["english"].month_abbr_value if you need it.)
I'm guessing that part of the documentation is outdated, and MONTHTOVALUE used to be month_value dict's older name.
There's also the function Dates.monthname_to_value, used like Dates.monthname_to_value("September",Dates.LOCALES["english"]), providing an interface into the above dict.

Answer 2

I've not heard of Julia, but passage seems relevant:
Support for text-form month parsing is also supported through the u
and U characters, for abbreviated and full-length month names,
respectively. By default, only English month names are supported, so u
corresponds to "Jan", "Feb", "Mar", etc. And U corresponds to
"January", "February", "March", etc. Similar to other name=>value
mapping functions dayname() and monthname(), custom locales can be
loaded by passing in the locale=>Dict{String,Int} mapping to the
MONTHTOVALUEABBR and MONTHTOVALUE dicts for abbreviated and full-name
month names, respectively.
https://docs.julialang.org/en/v0.6.2/manual/dates/
Edit: I think you can make the dictionary like this:
monthtovalue = Dict{UTF8String, Int}()
for (value, name) in VALUETOMONTH[locale::AbstractString="english"]
monthtovalue[lowercase(name)] = value
end