Assign Table variable name in Furncition · helpdesk (published)

function d(x,y)
        x=3
       y=8
end

d(dog,cat)

Brenhin Keller (May 30 2021 at 00:38):

dog, cat = 3, 8

Brenhin Keller (May 30 2021 at 00:39):

But whether or not that's something you want to to do maybe depends on what you're ultimately trying to accomplish

Mason Protter (May 30 2021 at 01:03):

It sounds like you're trying to run a function inside out. That's now how the data flows. When you write d(dog, cat), julia looks up what values are associate with the variables dog and cat and then passes those variables into the function d.

Inside the function, you then bind those values to the arguments, x and y, but then inside the function body you then rebind x and y to 3 and 8, completely ignoring whatever values were passed in

Mason Protter (May 30 2021 at 01:07):

If you want d to assign the values 3 and 8 to new variables dog and cat, then you can't do that with a function, but you can do it using a macro.

julia> macro d(x, y)
           ex = quote
               $x = 3
               $y = 8
           end
           esc(ex)
       end

@d (macro with 1 method)

julia> @d(dog, cat)
8

julia> dog + cat
11

brett knoss (May 30 2021 at 01:30):

That works, but apparently I can't do the same thing in a dataframes, or maybe I'm trying to send data both ways

macro transaction(newdate,newcredit,credit_amount,newdebit, debit_amount)
    if credit_amount != debit_amount
        "Error--Debit and Credit must match"
    else
        ex= quote

            newtransaction = DataFrame(
            $newdate=[newdate]
            $newcredit = [credit_amount],
            $newdebit = [debit_amount])
        end
        esc(ex)
    end
end

Mason Protter (May 30 2021 at 01:34):

brett knoss (May 30 2021 at 01:36):

Mason Protter (May 30 2021 at 01:38):

Mason Protter (May 30 2021 at 01:39):

new_transaction = transaction(newdate,newcredit,credit_amount,newdebit, debit_amount)

Mason Protter (May 30 2021 at 01:41):

julia> using DataFrames

julia> macro transaction(newdate,newcredit,credit_amount,newdebit, debit_amount)
           ex= quote
               if $credit_amount != $debit_amount
                   "Error--Debit and Credit must match"
               else
                   newtransaction = $DataFrame(
                       newdate=[$newdate],
                       newcredit = [$credit_amount],
                       newdebit = [$debit_amount]
                   )
               end
           end
           esc(ex)
       end
@transaction (macro with 1 method)

julia> @transaction(1, 2, 3, 4, 3)
1×3 DataFrame
 Row │ newdate  newcredit  newdebit
     │ Int64    Int64      Int64
─────┼──────────────────────────────
   1 │       1          3         3

brett knoss (May 30 2021 at 01:52):

macro transaction(newdate,newcredit,credit_amount,newdebit, debit_amount)
           ex= quote
               if $credit_amount != $debit_amount
                   "Error--Debit and Credit must match"
               else
                   newtransaction = $DataFrame(
                       Date=[$newdate],
                       $newcredit = [4],
                       $newdebit = [4]
                   )
               end
           end
           esc(ex)
       end
@transaction("Jan 1, 1900", chequing, 3, personal, 3)

Stream: helpdesk (published)

Topic: Assign Table variable name in Furncition

brett knoss (May 30 2021 at 00:32):