Print y-values at (local) extremes

[LukasP]

Hello,

is there a way GNUplot to write y-values at places where the y-value is a (local) extreme?

- Let's have a datafile with x and y values:

# x y
1 5
2 6
3 8
4 4
8 11
10 10

Than the y(x) plot of these data will have local maximum at [2; 6] and [8; 11] and the local minimum at [4; 4].

And I'm looking for a way that GNUplot would write "6" and "11" above points of local maximums and "4" above the local minimum.

Is it possible somehow?

- I know special cases should be solved - e.g. data:

0 5
2 6
3 6
4 6
5 2

It should be decided whether the [2; 6], [3; 6] and/or [4; 6] are extremes as well; but this is not the main question.

Or, is it possible the datafile to contain a special mark at points where the y-values are wanted to be written? E.g.:

# x y
1 5
2 6
3 8 # y
4 4 # Y
8 11 # y
10 10

Which should mean: when plotting - "# y" => "write the y-value above", "# Y" => "write the y-value bellow"?

See also the attachment for the wanted effect.

Thank you in advance.

Lukas
Clipboard01.png

[Thomas Sefzick]

the last case is 'easy':

plot "datafilename" with linespoints, \
"" using 1:2:(strlen("".stringcolumn(4)."")?("".stringcolumn(4)."" eq "Y")?stringcolumn(2):"":"") w labels offset 0,-1 rotate notitle, \
"" using 1:2:(strlen("".stringcolumn(4)."")?("".stringcolumn(4)."" eq "y")?stringcolumn(2):"":"") w labels offset 0,1 rotate notitle

LukasP wrote:

Hello,

is there a way GNUplot to write y-values at places where the y-value is a (local) extreme?

- Let's have a datafile with x and y values:

# x y
1 5
2 6
3 8
4 4
8 11
10 10

Than the y(x) plot of these data will have local maximum at [2; 6] and [8; 11] and the local minimum at [4; 4].

And I'm looking for a way that GNUplot would write "6" and "11" above points of local maximums and "4" above the local minimum.

Is it possible somehow?

- I know special cases should be solved - e.g. data:

0 5
2 6
3 6
4 6
5 2

It should be decided whether the [2; 6], [3; 6] and/or [4; 6] are extremes as well; but this is not the main question.

Or, is it possible the datafile to contain a special mark at points where the y-values are wanted to be written? E.g.:

# x y
1 5
2 6
3 8 # y
4 4 # Y
8 11 # y
10 10

Which should mean: when plotting - "# y" => "write the y-value above", "# Y" => "write the y-value bellow"?

See also the attachment for the wanted effect.

Thank you in advance.

Lukas
Clipboard01.png

[Thomas Sefzick]

try this with gnuplot 4.3-cvs:

set xrange [0:11]
set yrange [3:12]
up=0
plot 'datafilename' with linespoints, \
'' using ($0==0?x1=x2=$1:($0==1?($2>=y1?up=1:up=0):0,x1=x2)):\
         ($0==0?y1=y2=$2:y1=y2):\
         ($0==0?0/0:0 , x2=$1 , y2=$2 , \
          up==1?($2-y1<0?(up=0,sprintf("%d",y1)):0/0) \
               :($2-y1>0?(up=1,0/0):0/0)) \
   with labels offset 0,1 notitle , \
'' using ($0==0?x1=x2=$1:($0==1?($2>=y1?up=1:up=0):0,x1=x2)):\
         ($0==0?y1=y2=$2:y1=y2):\
         ($0==0?0/0:0 , x2=$1 , y2=$2 , \
          up==1?($2-y1<0?(up=0,0/0):0/0) \
               :($2-y1>0?(up=1,sprintf("%d",y1)):0/0)) \
   with labels offset 0,-1 notitle

LukasP wrote:

Hello,

is there a way GNUplot to write y-values at places where the y-value is a (local) extreme?

- Let's have a datafile with x and y values:

# x y
1 5
2 6
3 8
4 4
8 11
10 10

Than the y(x) plot of these data will have local maximum at [2; 6] and [8; 11] and the local minimum at [4; 4].

And I'm looking for a way that GNUplot would write "6" and "11" above points of local maximums and "4" above the local minimum.

Is it possible somehow?

- I know special cases should be solved - e.g. data:

0 5
2 6
3 6
4 6
5 2

It should be decided whether the [2; 6], [3; 6] and/or [4; 6] are extremes as well; but this is not the main question.

Or, is it possible the datafile to contain a special mark at points where the y-values are wanted to be written? E.g.:

# x y
1 5
2 6
3 8 # y
4 4 # Y
8 11 # y
10 10

Which should mean: when plotting - "# y" => "write the y-value above", "# Y" => "write the y-value bellow"?

See also the attachment for the wanted effect.

Thank you in advance.

Lukas
Clipboard01.png