Re: ranges.chunks and map! does not work

[vit via Digitalmars-d-learn]

On Thursday, 5 July 2018 at 09:47:32 UTC, Andre Pany wrote:
Hi,
the purpose of this code is to generate CSV based on 3 double 
arrays.
I wonder why map cannot directly use the result of the chunks 
function.

import std.experimental.all;

void main()
{
    double[] timestamps = [1.1];
    double[] temperatures = [2.2];
    double[] pressures = [3.3];

    string content = roundRobin(timestamps, temperatures, 
pressures)
        .chunks(3)
        //.map!(c => c.array)
        .map!(c => "%.10g,%.10g,%.10g".format(c[0],c[1],c[2]))
        .join("\n");

    writeln(content);
}

The exact error message is (this line is 3 times repeated):
app1.d(12): Error: no [] operator overload for type 
Take!(Result)
app1.d(12): Error: no [] operator overload for type 
Take!(Result)
app1.d(12): Error: no [] operator overload for type 
Take!(Result)
C:\SAPDevelop\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(499):
        instantiated from here: MapResult!(__lambda1, Chunks!(Result))
app1.d(12):        instantiated from here: map!(Chunks!(Result))

Is it correct that I need to call ".map!(c => c.array)"?

Kind regards
André

roundRobin doesn't return RandomAccessRange => chunks doesn't 
return range of RandomAccessRange => Error: no [] operator 
overload

try this:

    string content = roundRobin(timestamps, temperatures, 
pressures)
        .array
        .chunks(3)
        //.map!(c => c.array)
        .map!(c => "%.10g,%.10g,%.10g".format(c[0],c[1],c[2]))
        .join("\n");