# `bokeh.driving`¶

Provide a set of decorators useful for repeatedly updating a a function parameter in a specified way each time the function is called.

These decorators can be especially useful in conjunction with periodic callbacks in a Bokeh server application.

Example

As an example, consider the `bounce` forcing function, which advances a sequence forwards and backwards:

```from bokeh.driving import bounce

@bounce([0, 1, 2])
def update(i):
print(i)
```

If this function is repeatedly called, it will print the following sequence on standard out:

```0 1 2 2 1 0 0 1 2 2 1 ...
```
`bounce`(sequence)

Return a driver function that can advance a “bounced” sequence of values.

```seq = [0, 1, 2, 3]

# bounce(seq) => [0, 1, 2, 3, 3, 2, 1, 0, 0, 1, 2, ...]
```
Parameters: sequence (seq) – a sequence of values for the driver to bounce
`cosine`(w, A=1, phi=0, offset=0)

Return a driver function that can advance a sequence of cosine values.

```value = A * cos(w*i + phi) + offset
```
Parameters: w (float) – a frequency for the cosine driver A (float) – an amplitude for the cosine driver phi (float) – a phase offset to start the cosine driver with offset (float) – a global offset to add to the driver values
`count`()

Return a driver function that can advance a simple count.

`linear`(m=1, b=0)

Return a driver function that can advance a sequence of linear values.

```value = m * i + b
```
Parameters: m (float) – a slope for the linear driver x (float) – an offset for the linear driver
`repeat`(sequence)

Return a driver function that can advance a repeated of values.

```seq = [0, 1, 2, 3]

# repeat(seq) => [0, 1, 2, 3, 0, 1, 2, 3, 0, 1, ...]
```
Parameters: sequence (seq) – a sequence of values for the driver to bounce
`sine`(w, A=1, phi=0, offset=0)

Return a driver function that can advance a sequence of sine values.

```value = A * sin(w*i + phi) + offset
```
Parameters: w (float) – a frequency for the sine driver A (float) – an amplitude for the sine driver phi (float) – a phase offset to start the sine driver with offset (float) – a global offset to add to the driver values