None

Note

This tutorial was generated from an IPython notebook that can be accessed from github.

Creating own regions is straightforward. Import regionmask and check the version:

```import cartopy.crs as ccrs
import matplotlib.pyplot as plt
import numpy as np

```
```'0.11.0.post1.dev33+g8a1923d'
```

Import numpy

Assume you have two custom regions in the US, you can easily use these to create `Regions`:

```US1 = np.array([[-100.0, 30], [-100, 40], [-120, 35]])
US2 = np.array([[-100.0, 30], [-80, 30], [-80, 40], [-100, 40]])

```
```<regionmask.Regions 'unnamed'>
overlap:  None

Regions:
0 r0 Region0
1 r1 Region1

[2 regions]
```

Note

Set `overlap=True` if some of the regions overlap. See the tutorial on overlapping regions for details.

If you want to set the `names` and `abbrevs` yourself you can still do that:

```names = ["US_west", "US_east"]
abbrevs = ["USw", "USe"]

USregions = regionmask.Regions([US1, US2], names=names, abbrevs=abbrevs, name="US")
USregions
```
```<regionmask.Regions 'US'>
overlap:  None

Regions:
0 USw US_west
1 USe US_east

[2 regions]
```

Again we can plot the outline of the defined regions

```ax = USregions.plot(label="abbrev")

# fine tune the extent
ax.set_extent([225, 300, 25, 45], crs=ccrs.PlateCarree())
```

```import numpy as np

# define lat/ lon grid
lon = np.arange(200.5, 330, 1)
lat = np.arange(74.5, 15, -1)

```
```ax = plt.subplot(111, projection=ccrs.PlateCarree())

transform=ccrs.PlateCarree(),
cmap="Paired",
vmax=12,
)

ax.coastlines()

# add the outlines of the regions

ax.set_extent([225, 300, 25, 45], crs=ccrs.PlateCarree())
```

## Use shapely Polygon

You can also define the region with shapely polygons (see geopandas tutorial how to work with shapefiles).

```from shapely.geometry import MultiPolygon, Polygon

US1_poly = Polygon(US1)
US2_poly = Polygon(US2)

US1_poly, US2_poly
```
```(<POLYGON ((-100 30, -100 40, -120 35, -100 30))>,
<POLYGON ((-100 30, -80 30, -80 40, -100 40, -100 30))>)
```
```USregions_poly = regionmask.Regions([US1_poly, US2_poly])

USregions_poly
```
```<regionmask.Regions 'unnamed'>
overlap:  None

Regions:
0 r0 Region0
1 r1 Region1

[2 regions]
```

## Create Regions with MultiPolygon and interiors

Create two discontiguous regions and combine them to one. Add a hole to one of the regions

```US1_shifted = US1 - (5, 0)
US2_hole = np.array([[-98.0, 33], [-92, 33], [-92, 37], [-98, 37], [-98.0, 33]])
```

Create `Polygons`, a `MultiPolygon`, and finally `Regions`

```US1_poly = Polygon(US1_shifted)
US2_poly = Polygon(US2, holes=[US2_hole])

US_multipoly = MultiPolygon([US1_poly, US2_poly])

```
```USregions_poly.plot();
```

```mask = USregions_poly.mask(lon, lat)
```

and plot it:

```ax = plt.subplot(111, projection=ccrs.PlateCarree())