gnuplot

name	gnuplot
description	Render a Nushell table as an ASCII chart in the terminal using gnuplot's dumb terminal. Use when the user asks to "plot", "chart", "graph", or "visualize" tabular data they have in a Nushell pipeline or variable, or asks for a line chart, scatter plot, bar chart, or histogram of nu data shown as text in the terminal (no image file). Trigger on "plot this table", "show a chart of", "graph these numbers", "ascii chart", "gnuplot".
version	0.1.0

Plot Nushell tables with gnuplot (ASCII)

Turn a Nushell table into a text chart drawn in the terminal. Output is gnuplot's dumb terminal — characters, no image file. Good for eyeballing data and iterating in the loop.

Requires gnuplot on PATH (gnuplot --version). If missing, install it (brew install gnuplot).

The mechanism

Four steps. Always go through a temp data file — do not inline data with '-'/e.

1. Get the data into a Nushell table with numeric y-column(s).
2. Write it as headerless TSV to a temp file: $data | to tsv --noheaders | save -f /tmp/plot.dat
3. Build a plain gnuplot script string (not $"..." interpolation) that reads that path.
4. Pipe it to gnuplot and read stdout: $script | gnuplot | complete | get stdout

let data = [[x y]; [1 2] [2 4] [3 9] [4 16] [5 25]]
$data | to tsv --noheaders | save -f /tmp/plot.dat
"set terminal dumb size 72,22
set title 'y = x^2'
plot '/tmp/plot.dat' using 1:2 with linespoints title 'y'
" | gnuplot | complete | get stdout

Why a temp file, not inline '-' data: the data block stays out of the script string, so there is nothing to escape, and the same file can be referenced multiple times for multi-series plots. Inline data forces $"..." interpolation (which then needs \( \) escaping for xtic(1) etc.) and forces you to repeat the whole data block once per plotted series.

Recipes

A worked gallery of 17+ chart types with real rendered output — bars (clustered/stacked), histogram, impulses, steps, filled curves, error bars, candlesticks, smoothing, log axes, time series, multiplot, functions, and nu-pipeline→chart examples — is in references/gallery.md. The essentials:

All read /tmp/plot.dat written as in step 2. Column numbers in using are 1-based; using 0:N uses the row index (pseudo-column 0) as x — used for categorical x-axes.

Line / linespoints

"set terminal dumb size 72,22
plot '/tmp/plot.dat' using 1:2 with lines title 'y'
" | gnuplot | complete | get stdout

Multiple series (shared x, columns 2 and 3)

'' reuses the previously named file. set key outside keeps the legend off the plot.

"set terminal dumb size 72,18
set key outside
plot '/tmp/plot.dat' using 1:2 with lines title 'a', \
     ''             using 1:3 with lines title 'b'
" | gnuplot | complete | get stdout

Scatter

"set terminal dumb size 72,18
plot '/tmp/plot.dat' using 1:2 with points pt 7 title 'a'
" | gnuplot | complete | get stdout

Bar chart with categorical labels (column 1 = label, column 2 = value)

"set terminal dumb size 72,18
set style fill solid
set yrange [0:*]
plot '/tmp/plot.dat' using 2:xtic(1) with boxes title 'sales'
" | gnuplot | complete | get stdout

Histogram of one numeric column (bin a single column)

"set terminal dumb size 72,18
binwidth = 5
bin(x) = binwidth * floor(x / binwidth)
set boxwidth binwidth
set style fill solid
plot '/tmp/plot.dat' using (bin($1)):(1.0) smooth freq with boxes notitle
" | gnuplot | complete | get stdout

Gotchas

Problem	Fix
Header row plotted as a data point	to tsv --noheaders (not plain to tsv)
( / ) errors in the script	Don't use $"..." interpolation — keep the script a plain "..." string so xtic(1), bin($1) pass through literally
Categorical x labels (months, names)	using 2:xtic(1) (bars) or using 0:2:xtic(1) (lines) — column 1 supplies tic labels
$1, $2 (gnuplot column refs)	Pass through literally in a plain "..." string — Nushell only interpolates in $"...". Keep the script plain and write $1 as-is
Nulls / non-numeric y values	Filter in Nushell first (`where ($it.y
Plot too wide/narrow for terminal	Tune set terminal dumb size W,H (W ≈ 70–100, H ≈ 18–30)
Legend overlapping the curve	set key outside or set key off