Re: [Gnuplot-info] explanation to a short script

[Jon <dev...@gm...>]

Dear Thomas,

I actually specifically checked whether the first script could capture a
minimum hidden in the data except for the first line. The sample data I used
is

1  0.9
2  0.45
3  0.1
4  0.94
5  0.44
6  0.12
7  0.36

and it seems a single pass corrected identified 0.1 as the minimum. As to
your sample data, the missing of y range is a 2nd mysterious to me as if I
change the data to float, it works fine, and even if I interpret the data to
be integer, it should still give the right answer instead of giving constant
1 for each dataline.

Sincerely,
Jon


On Tue, Feb 15, 2011 at 2:31 AM, Thomas Sefzick <t.s...@fz...>wrote:

>
> strictly  speaking, nunzio's script only works if the smallest number is in
> the
> 1st data line.
>
> an example:
>
> #ts.dat:
> 1 10
> 2 9
> 3 8
> 4 7
> 5 6
> 6 5
> 7 4
> 8 3
> 9 2
> 10 1
>
> #script:
> min=10**10
> grab(x)=x<min?min=x:min=min
> plot 'ts.dat' using 1:($2/grab($2))
>
> gives a horizontal line and a warning about the empty y-range.
> this means that gnuplot behaves like other programming languages
> and there is no magic behind it.
>
> a 2nd plot gives the correct result, as you have pointed out,
> because then 'min' already contains the smallest value.
>
> #script:
> min=10**10
> grab(x)=x<min?min=x:min=min
> plot "ts.dat" using 1:($2/grab($2)), "" using 1:($2/grab($2))
>
> ... , "" using 1:($2/grab($2))
> is equivalent to
> ... , "" using 1:($2/min)
>
>
> bsmile wrote:
> >
> > Dear Thomas,
> >
> > Nunzio Losacco wrote a short script to get each number divided by the
> > smallest number in a specific column, as
> > min=10**10
> > grab(x)=x<min?min=x:min=min
> > plot 'disy.100' u 1:($3/grab($3))
> >
> > I don't quite understand the logic behind although I checked that it
> works
> > fine. If I were to do this, I would write something like
> >
> > set term dumb
> > min=10**10
> > plot 'disy.100' u ($3<min?min=$3:min=min,$1):3
> >
> > set term x11
> > plot 'disy.100' u 1:($3/min)
> >
> > and you easily see the idea I wrote it this way. I think this reflects a
> > big
> > problem for me to understand deeply how gnuplot deals with datafile and
> > how
> > it plots, which is obviously different from the standard programming
> > languages. Thanks for your in-depth explanation or references,
> >
> > Sincerely,
> > Jon
> >
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>
>
>
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