## Usage

### Edit Surface File

```python
from freesurfer_surface import Surface, Vertex, Triangle
surface = Surface.read_triangular('bert/surf/lh.pial'))
vertex_a = surface.add_vertex(Vertex(0.0, 0.0, 0.0))
vertex_b = surface.add_vertex(Vertex(1.0, 1.0, 1.0))
vertex_c = surface.add_vertex(Vertex(2.0, 2.0, 2.0))
surface.triangles.append(Triangle((vertex_a, vertex_b, vertex_c)))
surface.write_triangular('somewhere/else/lh.pial')
```

### List Labels in Annotation File

```python
from freesurfer_surface import Annotation

annotation = Annotation.read('tests/subjects/fabian/label/lh.aparc.annot')
for label in annotation.labels.values():
    print(label.index, label.hex_color_code, label.name)
```

or

```sh
$ freesurfer-annotation-labels tests/subjects/fabian/label/lh.aparc.annot
index	color	name
0	#190519	unknown
1	#196428	bankssts
2	#7d64a0	caudalanteriorcingulate
3	#641900	caudalmiddlefrontal
...
33	#4614aa	temporalpole
34	#9696c8	transversetemporal
35	#ffc020	insula
```

### Find Border of Labelled Region

```python
from freesurfer_surface import Surface
surface = Surface.read_triangular('bert/surf/lh.pial'))
surface.load_annotation_file('bert/label/lh.aparc.annot')
region, = filter(lambda l: l.name == 'precentral',
                 annotation.labels.values())
print(surface.find_label_border_polygonal_chains(region))
```