Le dimanche 29 mars 2015 à 09:46 -0700, Philip Tellis a écrit :
> On Sunday, March 29, 2015 at 6:47:32 AM UTC-4, Milan Bouchet-Valat
> wrote:
>
> Le samedi 28 mars 2015 à 21:35 -0700, Philip Tellis a écrit :
>
> > I've written the following code:
> >
> >
> > import Base.convert
> > function convert(::Type{UTF8String}, x::Int64)
> > return utf8(string(x))
> > end
> > println(convert(UTF8String, 10))
> > println(convert(Array{UTF8String, 1}, [10]))
> >
> >
> >
> > The intent is to convert an Array of Int64 into an Array of
> > UTF8String.
> >
> >
> > The first println works correctly and converts 10 into "10"
> >
> >
> > The second println should print an array of ["10"], but
> > instead gives me the following error:
> >
> >
> >
> > type: arrayset: expected UTF8String, got ASCIIString
> > while loading In[41], in expression starting on line 6
> >
> > in copy! at abstractarray.jl:149
> > in convert at array.jl:220
> >
> >
> >
> > I'm using Julia 0.3.6
> >
> >
> > Any idea on what I'm doing wrong?
>
> This works perfectly fine for me with 0.3.6 on Linux. Could
> you try at the Julia-REPL instead of IJulia (as you appear to
> be using). Can you post the output of versioninfo()?
>
>
> (FWIW, I'm not sure what you're trying to do is a great idea.
> convert is not defined that way because moving between numbers
> and strings is not considered a mere conversion, i.e. it
> should never happen automatically. Better give that function a
> different name, or use map() or a comprehension.)
>
>
>
>
>
>
>
> You're right, it does work on the julia REPL, so there could be
> something else in my running IJulia session that's interfering with
> it.
>
>
> As to my actual problem, what I have is a DataFrame with two columns,
> one a DataArray{UTF8String, 1} and the other a DataArray{Int64, 1},
> and I need to concatenate the two columns, but I can't do this because
> the * operator does not work with UTF8String & Int64. I suppose one
> option is for me to just cast the Int64 to a string in my SQL query
> that produces the dataframe.
Well, you don't need to overload convert to do that. One of the many
solutions, assuming a and b are the two columns:
df[:c] = ASCIIString[string(r[:a]) * r[:b] for r in eachrow(df)]
Regards
> I could also just concatenate the columns in SQL, but that would
> significantly increase the amount of data sent over the network
> between my db node and my julia compute node.
