The default *gnuplot* command `plot`

(also only `p`

) plot dataset with columns, of the form of the ** data_set.dat** file below.

```
# Prototype of a gnuplot data set
# data_set.dat
# X - X^2 - 2*X - Random
0 0 0 5
1 1 2 15
1.4142 2 2.8284 1
2 4 4 30
3 9 6 26.46
3.1415 9.8696 6.2832 39.11
4 16 8 20
4.5627 20.8182 9.1254 17
5.0 25.0 10.0 25.50
6 36 12 0.908
```

As you can see you can write in your data set in floating point notation. Now everything is ready to make the data plot: by typing only

```
plot "data_set.dat"
```

*gnuplot* will produce a graph in your `output`

destination. The default settings will use the first two columns of your data file, respectively x and y.
To specify the columns to be plotted use the ** using** specifier

```
plot "data_set.dat" using 2:4
```

which means "plot the file using column 2 as X and column 4 as Y". In the case your data set is a tridimensional file just use `splot`

ad add the z-column

```
splot "data_set.dat" using 1:2:3
```

There are also different style (see gnuplot documentation or Selecting a plotting style for further infos) for plotting points. As said before, the default style is `point`

```
plot "data_set.dat" using 1:4 with point
```

which will plot the same as if you do not type `with point`

. An useful style for data plotting is `linespoint`

which is, obviously, "lines + points". **E.G.:**

```
plot "data_set.dat" using 1:4 with linespoint
# the abbreviated form is completely equivalent:
# p "data_set.dat" u 1:4 w lp
```

**Forms of plotting iteration**

In the case you have more columns and want to plot them all in the same graph just pass to the `plot`

function any argument you prefer, by separating them with a `,`

:

```
p "data_set.dat" u 1:2 w lp,\
"data_set.dat" u 1:3 w lp,\
"data_set.dat" u 1:4 w lp
```

Anyway sometimes there could be too much columns to write one by one. In these case the `for`

iteration loop results very useful:

```
p for [col = 2:4] "data_set.dat" using 1:col w lp
```

which gives the output

Briefly the `for`

iteration increment the variable in the loop, in this case `col`

, with a decided steps (if not specified = 1). For example `for [i = 0:6:2]`

will increment `i`

from 0 to 6 in 2 steps: `i = 0, 2, 4, 6`

. All values (start, stop and increment) are casted to integer values.

***Grid**

The grid is often useful when plotting a data set. To add a grid type

```
set grid
```