diff --git a/mapshader/core.py b/mapshader/core.py
index 75d8074..ef97c4f 100644
--- a/mapshader/core.py
+++ b/mapshader/core.py
@@ -34,6 +34,35 @@ def create_agg(source: MapSource,
                x: float = None, y: float = None,
                z: float = None,
                height: int = 256, width: int = 256):
+    """
+    Instantiate an abstract canvas representing the space and compute
+    a reduction by pixel according to the geometry type applying the
+    aggregation function defined in source.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The map source object.
+    xmin : float
+        X-axis minimum range.
+    ymin : float
+        Y-axis minimum range.
+    xmax :float
+        X-axis maximum range.
+    ymax : float
+        Y-axis maximum range.
+    x, y, z : float
+        The coordinates to be used to get the bounds inclusive space along the axis.
+    height : int, default=256
+        Height of the output aggregate in pixels.
+    width : int, default=256
+        Width of the output aggregate in pixels.
+
+    Returns
+    -------
+    agg : xarray.DataArray
+        The transformed datasource.
+    """
 
     if x is not None and y is not None and z is not None:
         xmin, ymin, xmax, ymax = tile_def.get_tile_meters(x, y, z)
@@ -72,6 +101,25 @@ def create_agg(source: MapSource,
 
 
 def point_aggregation(cvs, data, xfield, yfield, zfield, agg_func):
+    """
+    Compute a reduction by pixel, mapping data to pixels as points.
+
+    Parameters
+    ----------
+    cvs : datashader.Canvas
+        The input canvas.
+    data : pandas.DataFrame, dask.DataFrame, or xarray.DataArray/Dataset
+        The input datasource.
+    xfield, yfield, zfield : str
+        Column names for the x, y, and z coordinates of each point.
+    agg_func : Reduction, optional
+        Reduction to compute. Default is ``count()``.
+
+    Returns
+    -------
+    agg : xarray.DataArray
+        The transformed datasource.
+    """
     if zfield:
         return cvs.points(data, xfield, yfield, getattr(ds, agg_func)(zfield))
     else:
@@ -79,6 +127,25 @@ def point_aggregation(cvs, data, xfield, yfield, zfield, agg_func):
 
 
 def line_aggregation(cvs, data, zfield, agg_func):
+    """
+    Compute a reduction by pixel, mapping data to pixels as one or more lines.
+
+    Parameters
+    ----------
+    cvs : datashader.Canvas
+        The input canvas.
+    data : pandas.DataFrame, dask.DataFrame, or xarray.DataArray/Dataset
+        The input datasource.
+    zfield : str
+        Column names for z coordinate of each point.
+    agg_func : Reduction, optional
+        Reduction to compute. Default is ``any()``.
+
+    Returns
+    -------
+    agg : xarray.DataArray
+        The transformed datasource.
+    """
     if zfield:
         return cvs.line(data,
                         geometry='geometry',
@@ -88,6 +155,26 @@ def line_aggregation(cvs, data, zfield, agg_func):
 
 
 def polygon_aggregation(cvs, data, zfield, agg_func):
+    """
+    Compute a reduction by pixel, mapping data to pixels as one or
+    more filled polygons.
+
+    Parameters
+    ----------
+    cvs : datashader.Canvas
+        The input canvas.
+    data : pandas.DataFrame, dask.DataFrame, or xarray.DataArray/Dataset
+        The input datasource.
+    zfield : str
+        Column names for z coordinate of each point.
+    agg_func : Reduction, optional
+        Reduction to compute. Default is ``any()``.
+
+    Returns
+    -------
+    agg : xarray.DataArray
+        The transformed datasource.
+    """
     if zfield:
         return cvs.polygons(data,
                             'geometry',
@@ -104,6 +191,35 @@ def get_data_array_extent(dataarray):
 
 
 def raster_aggregation(cvs, data, interpolate='linear', padding=0, agg_method=rd.max()):
+    """
+    Sample a raster dataset by canvas size and bounds.
+
+    Parameters
+    ----------
+    cvs : datashader.Canvas
+        The input canvas.
+    data : xarray.DataArray, xr.Dataset or dask.Array
+        The input datasource.
+    interpolate : str, default=linear
+        Resampling mode when upsampling raster.
+        Options include: nearest, linear.
+    padding : int, default=0
+        The padding to be added over the coordinates bounds range.
+    agg_method : Reduction, default=datashader.reductions.max()
+        Resampling mode when downsampling raster. The supported
+        options include: first, last, mean, mode, var, std, min,
+        The agg can be specified as either a string name or as a
+        reduction function, but note that the function object will
+        be used only to extract the agg type (mean, max, etc.) and
+        the optional column name; the hardcoded raster code
+        supports only a fixed set of reductions and ignores the
+        actual code of the provided agg.
+
+    Returns
+    -------
+    agg : xarray.DataArray
+        The transformed datasource.
+    """
     xmin, xmax = cvs.x_range
     ymin, ymax = cvs.y_range
     xdrange = (xmax - xmin) * (1 + 2 * padding)
@@ -142,6 +258,24 @@ def raster_aggregation(cvs, data, interpolate='linear', padding=0, agg_method=rd
                          'quantile': quantile}
 
 def apply_additional_transforms(source: MapSource, agg: xr.DataArray):
+    """
+    Apply additional transforms over the data, which options could be
+    ``hillshade`` or ``quantile``.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The map source object.
+    agg : xarray.DataArray
+        The transformed datasource.
+
+    Returns
+    -------
+    source : mapshader.sources.MapSource
+        The map source object.
+    agg : xarray.DataArray
+        The newly transformed datasource.
+    """
     agg = agg.astype('float64')
     agg.data[agg.data == 0] = np.nan
     for e in source.extras:
@@ -156,7 +290,30 @@ def apply_additional_transforms(source: MapSource, agg: xr.DataArray):
 
 
 def shade_discrete(agg, color_key, name='shaded', alpha=255, nodata=0):
-
+    """
+    Convert a DataArray to an image by choosing an RGBA pixel color
+    for each value by discrete approach.
+
+    Parameters
+    ----------
+    agg : xarray.DataArray
+        The input datasource.
+    color_key : dict
+        Categories colors.
+    name : str, default=shaded
+        Name of the datasource array.
+    alpha : int, default=255
+        Value between 0 - 255 representing the alpha value to use for
+        colormapped pixels that contain data.
+    nodata : int, default=0
+        The maximum data value, all the values less than this will be
+        replaced with 0.
+
+    Returns
+    -------
+    img : xarray.DataArray
+        A DataArray representing an image.
+    """
     if not agg.ndim == 2:
         raise ValueError("agg must be 2D")
 
@@ -201,6 +358,30 @@ def shade_discrete(agg, color_key, name='shaded', alpha=255, nodata=0):
 
 
 def shade_agg(source: MapSource, agg: xr.DataArray, xmin, ymin, xmax, ymax):
+    """
+    Convert a DataArray to an image by choosing an RGBA pixel color
+    for each value.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+    agg : xarray.DataArray
+        The input datasource.
+    xmin : float
+        X-axis minimum range.
+    ymin : float
+        Y-axis minimum range.
+    xmax : float
+        X-axis maximum range.
+    ymax : float
+        Y-axis maximum range.
+
+    Returns
+    -------
+    img : xarray.DataArray
+        A DataArray representing an image.
+    """
     df = source.data
     zfield = source.zfield
     geometry_type = source.geometry_type
@@ -240,7 +421,26 @@ def to_raster(source: MapSource,
               xmin: float = None, ymin: float = None,
               xmax: float = None, ymax: float = None,
               height: int = None, width: int = None):
-
+    """
+    Export a MapSource object to a raster object.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+    xmin : float
+        X-axis minimum range.
+    ymin : float
+        Y-axis minimum range.
+    xmax : float
+        X-axis maximum range.
+    ymax : float
+        Y-axis maximum range.
+    height : int
+        Height of the output aggregate in pixels.
+    width : int
+        Width of the output aggregate in pixels.
+    """
     if height is None and width is None:
         width = 1000
 
@@ -284,7 +484,28 @@ def render_map(source: MapSource,
                x: float = None, y: float = None,
                z: float = None,
                height: int = None, width: int = None, ):
-
+    """
+    Export a MapSource object to a map object.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+    xmin : float
+        X-axis minimum range.
+    ymin : float
+        Y-axis minimum range.
+    xmax : float
+        X-axis maximum range.
+    ymax : float
+        Y-axis maximum range.
+    x, y, z : float
+        The coordinates to be used to get the bounds inclusive space along the axis.
+    height : int
+        Height of the output aggregate in pixels.
+    width : int
+        Width of the output aggregate in pixels.
+    """
     if x is not None and y is not None and z is not None:
         xmin, ymin, xmax, ymax = tile_def.get_tile_meters(x, y, z)
 
@@ -339,8 +560,23 @@ def render_map(source: MapSource,
     return img
 
 
-def get_geojson(source: MapSource, simplify=None):
+def get_source_data(source: MapSource, simplify=None):
+    """
+    Get MapSource data and return as dict or GeoDataFrame depending on the geometry type.
 
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+    simplify : int, default=None
+        Get the simplified representation of each geometry according
+        to the toleranced distance.
+
+    Returns
+    -------
+    gdf : GeoDataFrame or dict
+        The Mapsource data
+    """
     if isinstance(source.data, spatialpandas.GeoDataFrame):
         gdf = source.data.to_geopandas()
 
@@ -361,19 +597,58 @@ def get_geojson(source: MapSource, simplify=None):
 
 
 def get_legend(source: MapSource):
+    """
+    Get the MapSource legend.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+
+    Returns
+    -------
+    legend : list of dict
+    """
     if source.legend is not None:
         return source.legend
     return []
 
 
 def render_geojson(source: MapSource, simplify=None):
-    geojson = get_geojson(source, simplify)
+    """
+    Export a MapSource object to a geojson object.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+    simplify : int, default=None
+        Get the simplified representation of each geometry according
+        to the toleranced distance.
+
+    Returns
+    -------
+    geojson : string
+    """
+    data = get_source_data(source, simplify)
 
-    if isinstance(geojson, dict):
-        return json.dumps(geojson)
+    if isinstance(data, dict):
+        return json.dumps(data)
 
-    return geojson.to_json()
+    return data.to_json()
 
 
 def render_legend(source: MapSource):
-    return json.dumps(render_legend(source))
+    """
+    Get the MapSource legend and return as a JSON string.
+
+    Parameters
+    ----------
+    source : mapshader.sources.MapSource
+        The input datasource.
+
+    Returns
+    -------
+    geojson : string
+    """
+    return json.dumps(get_legend(source))
diff --git a/mapshader/io.py b/mapshader/io.py
index 92ae6d3..6627158 100644
--- a/mapshader/io.py
+++ b/mapshader/io.py
@@ -12,6 +12,29 @@
 def load_raster(file_path, xmin=None, ymin=None,
                 xmax=None, ymax=None, chunks=None,
                 layername='data'):
+    """
+    Load raster data.
+
+    Parameters
+    ----------
+    file_path : str
+        Relative path to the file.
+    xmin : float
+        X-axis minimum range.
+    ymin : float
+        Y-axis minimum range.
+    xmax : float
+        X-axis maximum range.
+    ymax : float
+        Y-axis maximum range.
+    layername : str, default=data
+        Data layer name.
+
+    Returns
+    -------
+    arr : xarray.DataArray
+        The loaded data.
+    """
 
     if file_path.endswith('.tif'):
 
@@ -40,4 +63,17 @@ def load_raster(file_path, xmin=None, ymin=None,
 
 
 def load_vector(filepath: str):
+    """
+    Load vector data.
+
+    Parameters
+    ----------
+    filepath : str
+        Relative path to the file.
+
+    Returns
+    -------
+    gpd : geopandas.DataFrame
+        The loaded data.
+    """
     return gpd.read_file(filepath)
diff --git a/mapshader/mercator.py b/mapshader/mercator.py
index 0f2e7b4..672b14c 100644
--- a/mapshader/mercator.py
+++ b/mapshader/mercator.py
@@ -1,40 +1,47 @@
 import math
 
 def invert_y_tile(y, z):
-    # Convert from TMS to Google tile y coordinate, and vice versa
+    """
+    Convert from TMS to Google tile y coordinate, and vice versa
+    """
     return (2 ** z) - 1 - y
 
 
 # TODO: change name from source to definition
 class MercatorTileDefinition(object):
-    ''' Implementation of mercator tile source
-    In general, tile sources are used as a required input for ``TileRenderer``.
+    """
+    Implementation of mercator tile source. In general, tile sources
+    are used as a required input for ``TileRenderer``.
+
     Parameters
     ----------
     x_range : tuple
-      full extent of x dimension in data units
+        Full extent of x dimension in data units.
     y_range : tuple
-      full extent of y dimension in data units
+        Full extent of y dimension in data units.
     max_zoom : int
-      A maximum zoom level for the tile layer. This is the most zoomed-in level.
+        A maximum zoom level for the tile layer. This is the most
+        zoomed-in level.
     min_zoom : int
-      A minimum zoom level for the tile layer. This is the most zoomed-out level.
+        A minimum zoom level for the tile layer. This is the most
+        zoomed-out level.
     max_zoom : int
-      A maximum zoom level for the tile layer. This is the most zoomed-in level.
+        A maximum zoom level for the tile layer. This is the most
+        zoomed-in level.
     x_origin_offset : int
-      An x-offset in plot coordinates.
+        An x-offset in plot coordinates.
     y_origin_offset : int
-      An y-offset in plot coordinates.
+        An y-offset in plot coordinates.
     initial_resolution : int
-      Resolution (plot_units / pixels) of minimum zoom level of tileset
-      projection. None to auto-compute.
+        Resolution (plot_units / pixels) of minimum zoom level of
+        tileset projection. None to auto-compute.
     format : int
-      An y-offset in plot coordinates.
-    Output
-    ------
-    tileScheme: MercatorTileSource
-    '''
+        An y-offset in plot coordinates.
 
+    Returns
+    -------
+    tileScheme: MercatorTileDefinition
+    """
     def __init__(self, x_range, y_range, tile_size=256, min_zoom=0, max_zoom=30,
                  x_origin_offset=20037508.34, y_origin_offset=20037508.34,
                  initial_resolution=156543.03392804097):
@@ -49,16 +56,16 @@ def __init__(self, x_range, y_range, tile_size=256, min_zoom=0, max_zoom=30,
         self._resolutions = [self._get_resolution(z) for z in range(self.min_zoom, self.max_zoom+1)]
 
     def to_ogc_tile_metadata(self, output_file_path):
-        '''
+        """
         Create OGC tile metadata XML
-        '''
+        """
         pass
 
 
     def to_esri_tile_metadata(self, output_file_path):
-        '''
+        """
         Create ESRI tile metadata JSON
-        '''
+        """
         pass
 
 
diff --git a/mapshader/sources.py b/mapshader/sources.py
index 1a3ac7f..0f46e00 100644
--- a/mapshader/sources.py
+++ b/mapshader/sources.py
@@ -15,6 +15,86 @@
 
 
 class MapSource(object):
+    """
+    This class represents a map source object.
+
+    Parameters
+    ----------
+    name : str
+        Service name.
+    description : str
+        Service description.
+    filepath : str
+        Relative path to the data file.
+    legend : list of dict
+        Service legend, which could be defined the name, color, value,
+        and category.
+    config_path : str
+        Relative path to the config file.
+    data : geopandas.GeoDataFrame
+        Service source data.
+    geometry_type : str
+        Geometry type.
+    key : str
+        Service route root.
+    text : str
+        The service introduction text.
+    fields : list of str
+        The geometry fields.
+    span : str or tuple of int;
+        Min and max data values to use for colormap/alpha interpolation
+        when wishing to override autoranging.
+    geometry_field : str, default=geometry
+        The geometry field name.
+    xfield : str, default=geometry
+        The x field name.
+    yfield : str, default=geometry
+        The y field name.
+    zfield : str
+        The z field name.
+    agg_func : str
+        Reduction to compute.
+    raster_interpolate : str, default=linear
+        Resampling mode when upsampling raster.
+        Options include: nearest, linear.
+    shade_how : str, default=linear
+        The interpolation method to use. Valid strings are 'eq_hist',
+        'cbrt', 'log', and 'linear'.
+    cmap : list of colors or matplotlib.colors.Colormap, default=viridis
+        The colormap to use for 2D agg arrays.
+    color_key : dict or iterable
+        The colors to use for a 3D (categorical) agg array.
+    dynspread : int
+        The maximum number of pixels to spread on all shape sides.
+    extras : list of str
+        The additional transforms over the data, which options could be
+        'hillshade' or 'quantile'.
+    raster_padding : int, default=0
+        The padding to be added over the coordinates bounds range.
+    service_types : list of str
+        The service types, which options could be 'tile', 'image',
+        'wms', and 'geojson'.
+    full_extent : tuple of int
+        The coordinate of the lower left corner and the coordinate of
+        the upper right corner in map units.
+    default_extent : list of int
+        The service starting extent.
+    default_height : int, default=256
+        Height of the output aggregate in pixels.
+    default_width : int, default=256
+        Width of the output aggregate in pixels.
+    overviews : dict
+        The factors and values to be used when reducing the data
+        resolution.
+    transforms : list of dict
+        The transforms to be applied over the data, which options could
+        include: 'reproject_raster', 'reproject_vector', 'orient_array',
+        'cast', 'flip_coords', 'build_raster_overviews', 'build_vector_overviews',
+        'squeeze', 'to_spatialpandas', 'add_xy_fields', 'select_by_attributes',
+        'polygon_to_line', and 'raster_to_categorical_points'.
+    preload : bool, default=False
+        Preload the data after the service started.
+    """
 
     def __init__(self,
                  name=None,
@@ -134,7 +214,9 @@ def get_full_extent(self):
         raise NotImplementedError()
 
     def load(self):
-
+        """
+        Load the service data.
+        """
         if self.is_loaded:
             return self
 
@@ -220,6 +302,14 @@ def from_obj(obj: dict):
 
 
 class RasterSource(MapSource):
+    """
+    This class represents a raster source object.
+
+    Parameters
+    ----------
+    MapSource : mapshader.sources.MapSource
+        The map source object.
+    """
 
     @property
     def load_func(self):
@@ -235,6 +325,14 @@ def full_extent(self):
 
 
 class VectorSource(MapSource):
+    """
+    This class represents a vector source object.
+
+    Parameters
+    ----------
+    MapSource : mapshader.sources.MapSource
+        The map source object.
+    """
 
     @property
     def load_func(self):
@@ -250,6 +348,14 @@ def full_extent(self):
 
 
 class MapService():
+    """
+    This class represents a map service object.
+
+    Parameters
+    ----------
+    MapSource : mapshader.sources.MapSource
+        The map source object.
+    """
 
     def __init__(self, source: MapSource, renderers=[]):
         self.source = source
@@ -257,38 +363,65 @@ def __init__(self, source: MapSource, renderers=[]):
 
     @property
     def key(self):
+        """
+        Get the route before the coordinates.
+        """
         return f'{self.source.key}-{self.service_type}'
 
     @property
     def name(self):
+        """
+        Get the source name and service type.
+        """
         return f'{self.source.name} {self.service_type}'
 
     @property
     def legend_name(self):
+        """
+        Get the legend name.
+        """
         return f'{self.name}-legend'
 
     @property
     def default_extent(self):
+        """
+        Get the default extent.
+        """
         return self.source.default_extent
 
     @property
     def default_width(self):
+        """
+        Get the default width.
+        """
         return self.source.default_width
 
     @property
     def default_height(self):
+        """
+        Get the default height.
+        """
         return self.source.default_height
 
     @property
     def service_page_url(self):
+        """
+        Get the service page url.
+        """
         return f'/{self.key}'
 
     @property
     def legend_url(self):
+        """
+        Get the legend url.
+        """
         return f'/{self.key}/legend'
 
     @property
     def service_page_name(self):
+        """
+        Get the service page name.
+        """
         return f'/{self.key}-{self.service_type}'
 
     @property
@@ -309,6 +442,9 @@ def service_type(self):
 
 
 class TileService(MapService):
+    """
+    This class represents a tile service object.
+    """
 
     @property
     def service_url(self):
@@ -328,6 +464,9 @@ def service_type(self):
 
 
 class ImageService(MapService):
+    """
+    This class represents a image service object.
+    """
 
     @property
     def service_url(self):
@@ -356,6 +495,9 @@ def service_type(self):
         return 'image'
 
 class WMSService(MapService):
+    """
+    This class represents a WMS service object.
+    """
 
     @property
     def service_url(self):
@@ -385,6 +527,9 @@ def service_type(self):
 
 
 class GeoJSONService(MapService):
+    """
+    This class represents a GeoJSON service object.
+    """
 
     @property
     def service_url(self):
@@ -622,7 +767,19 @@ def elevation_source_netcdf():
 
 
 def parse_sources(source_objs, config_path=None, contains=None):
-
+    """
+    Parse ``mapshader.sources.MapSource`` and instantiate a
+    ``mapshader.sources.MapService``.
+
+    Parameters
+    ----------
+    source_objs : list of ``mapshader.sources.MapSource``
+        The map source objects.
+    config_path : str
+        Relative path to the config file.
+    contains : str
+        Skip the service type creation that contains this route.
+    """
     service_classes = {
         'tile': TileService,
         'wms': WMSService,
@@ -648,6 +805,20 @@ def parse_sources(source_objs, config_path=None, contains=None):
 
 
 def get_services(config_path=None, include_default=True, contains=None, sources=None):
+    """
+    Get the map services.
+
+    Parameters
+    ----------
+    config_path : str
+        Relative path to the config file.
+    include_default : bool, default=True
+        Include demo services.
+    contains : str
+        Skip the service type creation that contains this route.
+    sources : list of ``mapshader.sources.MapSource``
+        The map source objects.
+    """
 
     source_objs = None
 
diff --git a/mapshader/transforms.py b/mapshader/transforms.py
index e153895..c184dc5 100644
--- a/mapshader/transforms.py
+++ b/mapshader/transforms.py
@@ -22,6 +22,21 @@
 }
 
 def reproject_raster(arr: xr.DataArray, epsg=3857):
+    """
+    Reproject raster data.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        The raster data.
+    epsg : int
+        The coordinate systems code.
+
+    Returns
+    -------
+    reproj_data : xarray.DataArray
+        The reprojected data.
+    """
     global projections
 
     try:
@@ -32,39 +47,154 @@ def reproject_raster(arr: xr.DataArray, epsg=3857):
 
 
 def reproject_vector(gdf: gpd.GeoDataFrame, epsg=3857):
+    """
+    Reproject vector data.
+
+    Parameters
+    ----------
+    gdf : geopandas.GeoDataFrame
+        The vector data.
+    epsg : int
+        The coordinate systems code.
+
+    Returns
+    -------
+    reproj_data : geopandas.GeoDataFrame
+        The reprojected data.
+    """
     return gdf.to_crs(epsg=epsg)
 
 
 def flip_coords(arr, dim):
+    """
+    Flip the geometry coordinates.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        The data source.
+    dim : str
+        The coordinate field name.
+
+    Returns
+    -------
+    flipped_data : xarray.DataArray
+        The flipped coordinates data.
+    """
     args = {dim: list(reversed(arr.coords[dim]))}
     arr = arr.assign_coords(**args)
     return arr
 
 
 def to_spatialpandas(gdf: gpd.GeoDataFrame, geometry_field='geometry'):
+    """
+    Convert a ``geopandas.GeoDataFrame`` to ``spatialpandas.GeoDataFrame``.
+
+    Parameters
+    ----------
+    gdf : geopandas.GeoDataFrame
+        The data source.
+    geometry_field : str
+        Geometry field on GeoDataFrame
+
+    Returns
+    -------
+    spatial_gdf : spatialpandas.GeoDataFrame
+    """
     return spatialpandas.GeoDataFrame(gdf, geometry=geometry_field)
 
 
 def squeeze(arr, dim):
+    """
+    Return a new ``xarray.DataArray`` with squeezed data.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        The data source.
+    dim : str
+        Drop a specific field name.
+
+    Returns
+    -------
+    squeezed_data : xarray.DataArray
+        The squeezed data.
+    """
     return arr.squeeze().drop(dim)
 
 
 def cast(arr, dtype):
+    """
+    Cast the data to a specific data type.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        The data source.
+    dtype : str
+        Data type.
+
+    Returns
+    -------
+    casted_data : xarray.DataArray
+        The casted data.
+    """
     arr.data = arr.data.astype(dtype)
     return arr
 
 
 def orient_array(arr):
+    """
+    Reorients the array to a canonical orientation depending on
+    whether the x and y-resolution values are positive or negative.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        Data to be reoriented
+
+    Returns
+    -------
+    reoriented_data : numpy.ndarray
+        Reoriented 2d NumPy ndarray
+    """
     arr.data = ds.utils.orient_array(arr)
     return arr
 
 def get_data_array_extent(dataarray):
+    """
+    Get the coordinate of the lower left corner and the coordinate of
+    the upper right corner in map units.
+
+    Parameters
+    ----------
+    dataarray : xarray.DataArray
+        The input datasource.
+
+    Returns
+    -------
+    extent : tuple of integers
+        A tuple of ``(xmin, ymin, xmax, ymax)`` values.
+    """
     return (dataarray.coords['x'].min().item(),
             dataarray.coords['y'].min().item(),
             dataarray.coords['x'].max().item(),
             dataarray.coords['y'].max().item())
 
 def canvas_like(dataarray):
+    """
+    Get a ``datashader.Canvas`` according to a ``xarray.DataArray`` features.
+
+    Parameters
+    ----------
+    dataarray : xarray.DataArray
+        The input datasource.
+
+    Returns
+    -------
+    canvas : datashader.Canvas
+        An abstract canvas representing the space in which to bin.
+    """
 
     if isinstance(dataarray, xr.DataArray):
         extent = get_data_array_extent(dataarray)
@@ -81,6 +211,24 @@ def canvas_like(dataarray):
 
 
 def build_vector_overviews(gdf, levels, geometry_field='geometry'):
+    """
+    Reduce the vector data resolution.
+
+    Parameters
+    ----------
+    gdf : geopandas.GeoDataFrame
+        The vector data.
+    levels : dict
+        The factors and values to be used when reducing the data
+        resolution.
+    geometry_field : str, default=geometry
+        The geometry field name.
+
+    Returns
+    -------
+    overviews : geopandas.GeoDataFrame
+        The reduced resolution vector data.
+    """
     values = {}
     overviews = {}
     for level, simplify_tol in levels.items():
@@ -100,6 +248,25 @@ def build_vector_overviews(gdf, levels, geometry_field='geometry'):
 
 
 def build_raster_overviews(arr, levels, interpolate='linear'):
+    """
+    Reduce the raster data resolution.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        The raster data.
+    levels : dict
+        The factors and values to be used when reducing the data
+        resolution.
+    interpolate : str, default=linear
+        Resampling mode when upsampling raster.
+        Options include: nearest, linear.
+
+    Returns
+    -------
+    overviews : xarray.DataArray
+        The reduced resolution raster data.
+    """
     values = {}
     overviews = {}
     for level, resolution in levels.items():
@@ -127,12 +294,36 @@ def build_raster_overviews(arr, levels, interpolate='linear'):
 
 
 def add_xy_fields(gdf, geometry_field='geometry'):
+    """
+    Extract x and y fields from geometry and create new columns with them.
+    """
     gdf['X'] = gdf[geometry_field].apply(lambda p: p.x)
     gdf['Y'] = gdf[geometry_field].apply(lambda p: p.y)
     return gdf
 
 
 def select_by_attributes(gdf, field, value, operator='IN'):
+    """
+    Filter a ``geopandas.GeoDataFrame`` data.
+
+    Parameters
+    ----------
+    gdf : geopandas.GeoDataFrame
+        The vector data.
+    field : str
+        Column to be filtered.
+    value : int or float
+        Value to compare when filtering.
+    operator : str, default=IN
+        Arithmetic operator to be used when filtering.
+        Options include: IN, NOT IN, EQUALS, NOT EQUALS, LT, GT, LTE,
+        and GTE.
+
+    Returns
+    -------
+    filtered_data : geopandas.GeoDataFrame
+        The filtered data.
+    """
 
     if operator == 'IN':
         return gdf[gdf[field].isin(value)]
@@ -160,11 +351,43 @@ def select_by_attributes(gdf, field, value, operator='IN'):
 
 
 def polygon_to_line(gdf, geometry_field='geometry'):
+    """
+    Convert geometry type from polygon to line.
+
+    Parameters
+    ----------
+    gdf : geopandas.GeoDataFrame
+        The vector data.
+    geometry_field : str, default=geometry
+        The geometry field name.
+
+    Returns
+    -------
+    gdf : geopandas.GeoDataFrame
+        The converted data.
+    """
     gdf[geometry_field] = gdf[geometry_field].boundary
     return gdf
 
 
 def raster_to_categorical_points(arr, cats: dict, dim: str = 'data'):
+    """
+    Convert raster data to categorical points.
+
+    Parameters
+    ----------
+    arr : xarray.DataArray
+        The raster data.
+    cats : dict
+        Categories colors.
+    dim : str, default=data
+        The categorical column name.
+
+    Returns
+    -------
+    df : pandas.DataFrame
+        The converted data.
+    """
     df = None
     if isinstance(arr, da.Array):
         df = arr.compute().to_dataframe()
@@ -197,4 +420,12 @@ def raster_to_categorical_points(arr, cats: dict, dim: str = 'data'):
 
 
 def get_transform_by_name(name: str):
+    """
+    Get transform function by their name.
+
+    Parameters
+    ----------
+    name : str
+        The transform function name.
+    """
     return _transforms[name]