Welcome to colorella’s documentation!

Created On 2019-10-16, last modified @author: Felix Reuß felix.reuss@geo.tuwien.ac.at - includes functions from pytesmo package https://github.com/TUW-GEO/pytesmo

Colorella Package: Color organizing and easy to learn laboratory The packages allows to load color maps from several sources including: - matplotlib default colormaps (e.g viridis, plasma) - colorcet colormaps (e.g fire, rainbow) - cpt files - ct files - json - or to create new colormaps from dictionaries or lists of colors classmethods allow the following functions: - save a newly or modified colormap as .cpt, .ct or .json file - turn a colormap to greyscale (e.g. for printing in greyscale) - reverse a colormap - view a colormap as plot - load or convert to gdal colortable objects - create a list or dictionary object contaning all the colors from a colormap

class colorella.colormap.ColorMap(arg)

create a colormap object compatible with matplotlib

convert2greyscale(weights=1, inplace=True)

Return a grayscale version of the given colormap. Luminanance values are calculated using a dot product of a weight array and the color array of the object

Parameters
  • weights (int) – weights used to convert RGB values to luminance, default =1

  • inplace (bool) – if True the original object is replaced, if False a new ColorMap object is returned

Returns

Return type

ColorMap object if inpalce = False

classmethod from_cptfile(filepath, gradient=True)

Create a LinearSegmented Colormap from a .cpt file

Parameters

filepath (str) – absolute filepath including filename and extension of the cpt file

Returns

Return type

ColorMap object (LinearSegmented Colormap object)

classmethod from_ctfile(filepath, gradient=True)

Create a Listed Colormap from a gdal .ct file

Parameters

filepath (str) – absolute filepath including filename and extension of the ct file

Returns

Return type

ColorMap object (Listed Colormap object)

classmethod from_dict(cdict, name='default')

Create color map from linear mapping segments Parameters: ———- cdict: dictionary

cdict argument is a dictionary with a red, green and blue

entries. Each entry should be a list of x, y0, y1 tuples, forming rows in a table. Entries for alpha are optional.

example from matplotlib: suppose you want red to increase from 0 to 1 over

the bottom half, green to do the same over the middle half, and blue over the top half. Then you would use:

cdict = {'red':   [(0.0,  0.0, 0.0),
                   (0.5,  1.0, 1.0),
                   (1.0,  1.0, 1.0)],

         'green': [(0.0,  0.0, 0.0),
                   (0.25, 0.0, 0.0),
                   (0.75, 1.0, 1.0),
                   (1.0,  1.0, 1.0)],

         'blue':  [(0.0,  0.0, 0.0),
                   (0.5,  0.0, 0.0),
                   (1.0,  1.0, 1.0)]}

Each row in the table for a given color is a sequence of x, y0, y1 tuples. In each sequence, x must increase monotonically from 0 to 1. For any input value z falling between x[i] and x[i+1], the output value of a given color will be linearly interpolated between y1[i] and y0[i+1]:

row i:   x  y0  y1
               /
              /
row i+1: x  y0  y1

Hence y0 in the first row and y1 in the last row are never used.

name: str

name of the Colormap

Returns

Return type

ColorMap object (LinearSegmented Colormap object)

classmethod from_file(filepath, name=None, gradient=True)

Function to open colormap objects from .cpt, .ct, .json files

filepath: str

path and filename of the colormap to be opened

name: str, optional

name of the Colormap

Returns

Return type

ColorMap object

classmethod from_gdal(ct)

Converts a gdal Colortable to a matplotlib colormap

Parameters

ct (gdal colortable object) – gdal colortable object from which a ColorMap shall be created

Returns

Return type

ColorMap object (Listed Colormap object)

classmethod from_jsonfile(filepath)

Creates a LinearSegmented Colormap from a .json file

Parameters

filepath (str) – absolute filepath including filename and extension of the json file

Returns

Return type

ColorMap object (LinearSegmented or Listed Colormap object)

classmethod from_list(clist, name='default', gradient=False)

Make a linear segmented colormap with name from a sequence of colors which evenly transitions from colors[0] at val=0 to colors[-1] at val=1. Alternatively, a list of (value, color) tuples can be given to divide

Parameters
  • clist (list) – list of colors given as RGBA tuples

  • name (str) – name of the Colormap

  • gradient (bool) – if False a Listed Colormap is created, if True a LinearSegmented Colormap is created

Returns

Return type

ColorMap object (LinearSegmented or Listed Colormap object)

property name

Returns attribute name

Returns

Return type

attribute name

reverse(inplace=True)

Reverses a colormap, a.k.a returns the containing colors in reverse direction. Class type remains the same

Parameters

inplace (bool) – if True the original object is replaced, if False a new ColorMap object is returned

Returns

Return type

ColorMap object if inplace = False

save_as_cpt(outpath=None, **kwargs)

Saves a acolormap.object as a .cpt file

Parameters
  • outname (str, optional) – outname for the file

  • keyword arguments (int) – Vmin, Vmax, N (Number of colorsteps)

save_as_ct(outpath=None)

Saves a colormap.object as a gdal .ct file

Parameters

outname (str, optional) – outname for the file

save_as_json(outpath=None)

Saves a colormap.object as a gdal .ct file

Parameters

outname (str, optional) – outname for the file

show()

Shows the colormap as a colorbar in a plot

to_dict()

Creates a dictionary of colors from a colormap object

Returns

Return type

dict object

to_gdal(accelerate=1)

Converts a ColorMap object to a gdal colortable object

Parameters

accelerate (int) – scale factor applied to Colors

Returns

Return type

Gdal color table object

to_gradient(inplace=True)

Converts a listed Colormap to a Linear Segmented Colormap

Parameters
  • outname (str, optional) – filename if the colormap is saved

  • inplace (bool) – if True the original object is replaced, if False a new ColorMap object is returned

Returns

Return type

ColorMap object is inplace = False

to_list()

Creates a list of colors from a colormap object

Returns

Return type

List object

to_matplotlib()

Returns the matplotlib colormap object

Returns

Return type

matplotlib colormap object

Indices and tables