# Hyperparameter Search: Grid¶

The `grid`

search method generates trials on a “grid” of
hyperparameter configurations and trains each trial for `max_steps`

steps. The user specifies a set of values for each hyperparameter via
the `hyperparameters`

field in the experiment config file. The “grid”
of hyperparameter configurations is generated by taking the
product of these
sets. For example, if the set of values for three separate
hyperparameters `aparam`

, `bparam`

, and `cparam`

are specified as
`{0, 1, 2}`

, `{10, 20}`

, and `{"c"}`

respectively, then the grid
of tuples `(aparam, bparam, cparam)`

generated is:

```
(0, 10, "c")
(0, 20, "c")
(1, 10, "c")
(1, 20, "c")
(2, 10, "c")
(2, 20, "c")
```

The way the set of hyperparameter values is specified depends on the type of hyperparameter:

`const`

: The set of values contains just the single value. For example,`cparam`

above could be specified as a`const`

hyperparameter with`val: c`

.`categorical`

: The set of values is exactly the set of categorical values. For example,`bparam`

above could be specified as a`categorical`

hyperparameter with`vals: [10, 20]`

.`int`

: The set of`count`

values is taken evenly from the range`[minval, maxval]`

, inclusive of endpoints. If`count`

is larger than the number of integer values in the range, that is interpreted as the entire range of integers in`[minval, maxval]`

. For example,`aparam`

above could be specified as an`int`

hyperparameter with`minval: 0`

,`maxval: 2`

, and`count: 3`

or`count: 100`

.`double`

: The set of`count`

values is taken evenly from the range`[minval, maxval]`

, inclusive of endpoints. The set`{0.1, 0.3, 0.5}`

could be specified as a`double`

hyperparameter with`minval: 0.1`

,`maxval: 0.5`

,`count: 3`

.`log`

: The set of`count`

values is taken logarithmically evenly from the range [baseminval, basemaxval], inclusive of endpoints. For example, the set`{0.00001, 0.0001, 0.001}`

could be specified as a`log`

hyperparameter with`base: 10`

,`minval: -5`

,`maxval: -3`

, and`count: 3`

.

Under the special case of `count: 1`

for `int`

, `double`

, or
`log`

, the midpoint (with rounding for `int`

and with basemidpoint
for `log`

) is returned.