Re: [Gnuplot-info] Gnuplot: How to convert STRINGS in DOUBLE? (with AWK)

[Thomas S. <t.s...@fz...>]

the 'system' command returns a string which used as the first argument in
a plot command will be interpreted as a filename - that's the way gnuplot
is instructed to read data from a file.
just tell gnuplot that 'GewMW' doesn't contain a filename but a numerical
value:
plot 1.*GewMW


AstroPhysik wrote:
> 
> Hi Folks!
> How can i convert in gnuplot strings to double?
> 
> I use AWK for calculating in a data file some weighted means. The result
> should be displayed in gnuplot.
> 
> GewMW = system("gawk '{total+=$7; Nges+=1; Mean =
> total/Nges;PhysikalischeWerte[$7] = $7;for(i=1; i<=Nges;i++) Gewichtung[i]
> =  100.00 -((100.00/Nges) * (i-1));for(i=1; i<=Nges;i++) SummeGewichtung
> += Gewichtung[i];for(i=1; i<=Nges;i++) SummeMW += (Mean *
> Gewichtung[i]);GewichteterMittelwert =SummeMW /SummeGewichtung; } END
> {print GewichteterMittelwert }' Stern.dat");
> 
> 
> print GewMW
> 
> print GewMW shows the correct result but AWK or Gnuplot convert here the
> result to a string: "GewMW = system(..)"  which is saved in GewMW.
> This string i cannot process with plot..
> 
> plot "Stern.dat"   using 7,  f(x) t "mean <x>" ,  GewMW t "w.mean" w l
> 
> .. shows only the first mean but not the weighted mean from the value
> GewMW (because it is a string here..)
> 
> i've also written a small  C++ Programm "stringToDouble(.. string )" which
> returns a double, but i cannot call it in the correct way from gnuplot?
> 
> GewMW = system(  stringtodouble(GewMW) );
> GewMW = system("./stringtodouble(GewMW)");
> 
> The Listnings above bring  the errormessages:
> "Star.dat", line 93: undefined function: stringtodouble
> and:
> sh: Syntax error: word unexpected (expecting ")")
> 
> I also tried to save the output to a file..
> 
> save '|grep GewMW >temp.dat';
> 
> and try to re-read it in gnuplot, hoping it will be interpreted as a
> numeric value (double)..
> 
> Ähhhmmm, yes.. so faar.. nothing is working..
> 
> Does anyone have a tip which is more elegant/beautiful as mine are?
> 
> Thank you, :-)
> AstroPhysik
> 

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