Re: [Gnuplot-info] Access data value in file

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

with gnuplot 4.3 it's possible:

normalize to the maximum y-value:

max(a,b)=a>b?a:b
a=-99999999.
plot 'datafile' using 1:(a=max(a,$2),0/0) notitle, '' using 1:($2/a) with
linespoints

explanation:
1st you plot nothing ('0/0') but you determine the maximum value in
column '2', in the 2nd plot you use this maximum value.

instead of determining the maximum y-value you could also choose any
y-value (e.g. the one in line '4' of your datafile):

plot 'datafile' using 1:(a=$2,0/0) every 1:1:3:0:3:0 notitle, '' using
1:($2/a) with linespoints


uli80 wrote:
> 
> Dear all,
> 
> I've been using Gnuplot since years as my standard plotting tool. But
> there is one thing, that I still could not find out. Maybe there is anyone
> in this forum who can answer the following question:
> 
> I have a data file containing two columns: x and y values. 
> How can I get access to one value a = y(x)?
> 
> This value I need e.g. to normalize all values in a plot:
> 
> plot 'data.txt' using 1:($2/a)
> 
> 
> Thank you very much for any idea!!
> 

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