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Re: [naive] hash assingment

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From:
Clifton Wood
Date:
July 14, 2021 18:55
Subject:
Re: [naive] hash assingment
Message ID:
CADaz7Gk8XZaYW9XYdD9N8hbZERvXQ6yJ71hhqyuEmy0pQPExLA@mail.gmail.com
Unfortunately, given this:

my %a = 'column1' => [1...5], 'column2' => ['a'...'e']
>

column1 and column2 cannot yet be referenced to create column3.

You need to do that on another line:

%a<column3> = %a<column1>.map: { .sqrt };

Which gives the following:

> %a.gist.say
# {column1 => [1 2 3 4 5], column2 => [a b c d e], column3 => (1
1.4142135623730951 1.7320508075688772 2 2.23606797749979)}

Does this help?

- X

On Wed, Jul 14, 2021 at 2:32 PM Aureliano Guedes <guedes.aureliano@gmail.com>
wrote:

> Thanks JJ, Marcel, Matthew
>
> That's help me a lot to understand how Raku hashes work;
> Little bit complex compared to Perl5.
>
> But now I got another question
>
> given
> my %a = 'column1' => [1...5], 'column2' => ['a'...'e']
>
> I want to calculate sqrt and store in column3
> > %a{'column1'}.map({ .sqrt })
> (1 1.4142135623730951 1.7320508075688772 2 2.23606797749979)
> > %a{'column3'} = %a{'column1'}.map({ .sqrt })
> > %a{'column3'}
> (1 1.4142135623730951 1.7320508075688772 2 2.23606797749979)
> > %a.keys
> (column1 column3 column2)
>
> But...
> > %a{'column1'} ==> map( { .sqrt } )
> (2.23606797749979)
>
> How I access the array's values within the hash?
>
>
> On Wed, Jul 14, 2021 at 2:55 PM Marcel Timmerman <mt1957@gmail.com> wrote:
>
>> On 7/14/21 7:43 PM, Aureliano Guedes wrote:
>>
>> Hi all,
>>
>> Trying to knowing a little bit more about Raku lang, I decided to write a
>> simple (as possible) lib to became similar to R/dplyr or Python/Pandas
>> method to data wrangle.
>>
>> So, Raku gives us the possibility to deal with data in a functional way,
>> given the native pipe operator, which is wonderful for newbies.
>> > @a = 1..100
>> > @a ==> map( { .sqrt } )
>> > @a ==> HYPER( { .sqrt } ) # faster map
>> Even it is being *too verbose*, is good enough for the first moment to a
>> data scientist.
>>
>> So I'm trying to decide the best way to abstract columns.
>> First, I decide to use a hash where the key is the column name and the
>> value is the oriented list ou array.
>>
>> > my %a = {'column1' => [1...5], 'column2' => ['a'...'e']}
>> Potential difficulties:
>>     Useless use of hash composer on right side of hash assignment; did
>> you mean := instead?
>>     at line 2
>>     ------> <BOL>⏏<EOL>
>> {column1 => [1 2 3 4 5], column2 => [a b c d e]}
>>
>> It is a warning, not an error!
>>
>> But let's obey the warning.
>> > my %a = {'column1' := [1...5], 'column2' := ['a'...'e']}
>> ===SORRY!=== Error while compiling:
>> Cannot use bind operator with this left-hand side
>> ------> n1' := [1...5], 'column2' := ['a'...'e']⏏}
>>
>>
>> ':=' in the error is meant to replace the assignment so you are binding
>> directly to the hash.
>> So write,
>>
>> my %a := {'column1' => [1...5], 'column2' => ['a'...'e']}
>>
>> Without the binding you could write instead
>>
>> my %a = 'column1' => [1...5], 'column2' => ['a'...'e']
>>
>> See also https://docs.raku.org/type/Hash and
>> https://docs.raku.org/routine/:=
>>
>>
>> Now we got an error.
>>
>> Someone may explain me why I got this error??
>>
>> Thanks in advance
>>
>>
>>
>>
>> --
>> Aureliano Guedes
>> skype: aureliano.guedes
>> contato:  (11) 94292-6110
>> whatsapp +5511942926110
>>
>>
>>
>
> --
> Aureliano Guedes
> skype: aureliano.guedes
> contato:  (11) 94292-6110
> whatsapp +5511942926110
>

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