gnuplot-info

[Gnuplot-info] How to plot the last data points of each block?

[theozh <th...@gm...>]

In the following simplified dataset I just want to plot the last point of each block, here: 7, 4, 1.
How can I do that? 
Isn't there anything like: plot $Data u 0:1 every ::-1::-1

$Data <<EOD
9
8
7

6
5
4

3
2
1
EOD

# With the following:

stats $Data using 1
plot $Data index STATS_blocks-1 w lp

I could plot the complete last block (3,2,1), but ONLY if there were 2 empty lines between the blocks.
But I need to plot the last point of each block, i.e. 7, 4, 1

Re: [Gnuplot-info] How to plot the last data points of each block?

[theozh <th...@gm...>]

still nobody has an idea...?

Well, since the construct
  plot $Data u 1:2 every ::-1::-1
does not exist... here is an ugly workaround (see below).
It basically reverses a dataset and plots the first datapoint of each datablock. 
Maybe someone else might find it useful or even knows a better and more elegant way to achieve this.
If it can be done easier using awk, gawk, sed, etc. please let me know how.
But the following is a pure gnuplot solution.

### plot the last point of each datablock
reset
$Data <<EOD
11 1
22 4
33 9

44 16
55 25
66 36
77 49

88 64
99 81
110 100
121 121
132 144
EOD

print $Data
stats $Data
print STATS_records    # number of datapoints

array A[STATS_records]   # helper array
array B[STATS_records]   # helper array
array C[STATS_records]   # helper array

# puttig the dataset into arrays
set table $Data2
plot $Data u (A[$0+1]=column(-1),column(-1)):(B[$0+1]=$1,$1):(C[$0+1]=$2,$2) with table
unset table
print $Data2

# reverse the dataset
set print $Data3
G = A[STATS_records] # initialize block indicator
do for [i=STATS_records:1:-1] { 
  if (A[i] != G) { print "" }  # if different insert empty line / start new block
  G = A[i] 
  print sprintf("%g %g", B[i], C[i])
}
set print
print $Data3

# plot the original values 
set key top left
plot $Data u 1:2 w lp

# plot the first datapoints of each datablock of the reversed dataset
replot $Data3 u 1:2 every ::0::0 w p pt 6 ps 3 t "last point of each datablock"

### end gnuplot code

Re: [Gnuplot-info] How to plot the last data points of each block?

[BBands <bb...@gm...>]

Probably not what you want, but I preprocess the data in VisualBasic or
Python and then pass just the data to be plotted to gnuplot.

Best,

      John

On Fri, Dec 1, 2017 at 3:26 PM, theozh <th...@gm...> wrote:

> still nobody has an idea...?
>
> Well, since the construct
>   plot $Data u 1:2 every ::-1::-1
> does not exist... here is an ugly workaround (see below).
> It basically reverses a dataset and plots the first datapoint of each
> datablock.
> Maybe someone else might find it useful or even knows a better and more
> elegant way to achieve this.
> If it can be done easier using awk, gawk, sed, etc. please let me know how.
> But the following is a pure gnuplot solution.
>
> ### plot the last point of each datablock
> reset
> $Data <<EOD
> 11 1
> 22 4
> 33 9
>
> 44 16
> 55 25
> 66 36
> 77 49
>
> 88 64
> 99 81
> 110 100
> 121 121
> 132 144
> EOD
>
> print $Data
> stats $Data
> print STATS_records    # number of datapoints
>
> array A[STATS_records]   # helper array
> array B[STATS_records]   # helper array
> array C[STATS_records]   # helper array
>
> # puttig the dataset into arrays
> set table $Data2
> plot $Data u (A[$0+1]=column(-1),column(-1)):(B[$0+1]=$1,$1):(C[$0+1]=$2,$2)
> with table
> unset table
> print $Data2
>
> # reverse the dataset
> set print $Data3
> G = A[STATS_records] # initialize block indicator
> do for [i=STATS_records:1:-1] {
>   if (A[i] != G) { print "" }  # if different insert empty line / start
> new block
>   G = A[i]
>   print sprintf("%g %g", B[i], C[i])
> }
> set print
> print $Data3
>
> # plot the original values
> set key top left
> plot $Data u 1:2 w lp
>
> # plot the first datapoints of each datablock of the reversed dataset
> replot $Data3 u 1:2 every ::0::0 w p pt 6 ps 3 t "last point of each
> datablock"
>
> ### end gnuplot code
>
>
>
> ------------------------------------------------------------
> ------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> gnuplot-info mailing list
> gnu...@li...
> Membership management via: https://lists.sourceforge.net/
> lists/listinfo/gnuplot-info
>