Colour maps
===========
Colour maps can be specified with the colourmap() function
Calling colourmap() on a vis object loads a colourmap and applies it to
that object in a single command.
It can also be called from the viewer object which just loads a
colourmap and returns its id, which can be saved and used to set the
“colourmap” property of a one or more or objects.
.. code:: ipython3
#First set up a basic vis so we can display the colourmaps
import lavavu
lv = lavavu.Viewer(border=False, axis=False, background="gray90", quality=3, fontscale=1.5)
**Specifying colour maps**
Maps can be loaded as strings or lists of colours, positions can
optionally be provided in range [0,1] to set where on the scale the
colour will be placed, eg:
::
"red white blue"
"0.0=red 0.25=white 1.0=blue"
[(0.0, 'red'), (0.25, 'white'), (1.0, 'blue')]
['red', 'white', 'blue']
To provide specific values for colours in their original scale (rather
than positions normalized to [0,1] range), place the value in
parenthesis instead, eg:
::
"red (100)white (200)blue"
When specifying colours you can use either: 1. colour names from
https://en.wikipedia.org/wiki/X11_color_names eg: ‘red’ 2. RGB hex
values such as ‘#ff0000’ 3. HTML style rgb(a) values, eg: ‘rgb(255,0,0)’
or ‘rgba(255,0,0,1)’
| Colour order and positions can be reversed by passing *reverse=True*.
| Pass *discrete=True* to produce a discrete colour map instead of a
continuously varying one.
| *log=True* will apply a logarithmic scale.
| Addional properties to the colour map can be passed, for details see:
https://lavavu.github.io/Documentation/Property-Reference#colourmap
**Colour bars**
The colourbar() function creates a colour bar plot, it can be called
from an object and uses that objects colour map, if called on the viewer
it must have its map specified at some point with colourmap(data).
There are several properties that specify how the colour bar is
displayed, see:
https://lavavu.github.io/Documentation/Property-Reference#colourbar
.. code:: ipython3
#Create colour bar then load a colourmap into it
cbar1 = lv.colourbar(size=[0.95,15], align="top")
cbar1.colourmap([(0, 'green'), (0.75, 'yellow'), (1, 'red')], reverse=True)
.. parsed-literal::
"""0.0000=rgba(255,0,0,1)
0.2500=rgba(255,255,0,1)
1.0000=rgba(0,255,0,1)
"""
.. code:: ipython3
#Create another colour bar and load a map, this time with a log scale
cbar2 = lv.colourbar(size=[0.95,15], align="top", tickvalues=[20,50,100,200,500])
cbar2.colourmap('black (100)goldenrod (101)khaki white', range=[10,1000], logscale=True)
.. parsed-literal::
"""0.0000=rgba(0,0,0,1)
0.5000=rgba(218,165,32,1)
0.5022=rgba(240,230,140,1)
1.0000=rgba(255,255,255,1)
"""
.. code:: ipython3
lv.display(resolution=[640,90], transparent=True)
.. raw:: html
.. code:: ipython3
print(cbar1)
.. parsed-literal::
{
align="top"
colourbar=true
colourmap="colourbar_colourmap"
name="colourbar"
size=[0.95, 15]
visible=true
}
**CubeHelix**
Custom `cube helix `__ maps
can be generated with cubehelix(), these will always have monotonically
varying intensity values to be when printed in greyscale
.. code:: ipython3
cbar1.colourmap(lavavu.cubehelix(samples=16, start=0.5, rot=-0.9, sat=1.0, gamma=1.0, alpha=False))
cbar2.colourmap(lavavu.cubehelix(samples=16, start=1.0, rot=0.9, sat=0.75, gamma=1.0, alpha=False), logscale=False)
cbar2["tickvalues"] = []
lv.display(resolution=[640,90], transparent=True)
#Display in greyscale
cbar1.colourmap(lavavu.cubehelix(samples=16, start=0.5, rot=-0.9, sat=1.0, gamma=1.0, alpha=False), monochrome=True)
cbar2.colourmap(lavavu.cubehelix(samples=16, start=1.0, rot=0.9, sat=0.75, gamma=1.0, alpha=False), monochrome=True)
lv.display(resolution=[640,90], transparent=True)
.. raw:: html
.. raw:: html
**Getting data**
Colourmap data can be retreived with .getcolourmap() on an object, which
returns the map formatted as a string, .getcolourmap(string=False)
returns a python list of (position, colour) tuples instead. Either of
these formats are supported when creating a colourmap so the data can be
modified and passed to a new colour map.
.. code:: ipython3
print(cbar1.getcolourmap())
.. parsed-literal::
"""0.0000=rgba(0,0,0,1); 0.0625=rgba(21,21,21,1); 0.1250=rgba(38,38,38,1); 0.1875=rgba(54,54,54,1); 0.2500=rgba(73,73,73,1); 0.3125=rgba(93,93,93,1); 0.3750=rgba(114,114,114,1); 0.4375=rgba(133,133,133,1); 0.5000=rgba(147,147,147,1); 0.5625=rgba(158,158,158,1); 0.6250=rgba(168,168,168,1); 0.6875=rgba(179,179,179,1); 0.7500=rgba(192,192,192,1); 0.8125=rgba(208,208,208,1); 0.8750=rgba(222,222,222,1); 0.9375=rgba(236,236,236,1); 1.0000=rgba(255,255,255,1); """
**CPT colour tables**
| Most files in the Generic Map Tools CPT format can be imported.
| A large library of these can be found at
`cpt-city `__
The *positions=False* argument can be passed to ignore the position data
and load only the colours.
.. code:: ipython3
try:
#Check if file exists, if not download it from cpt-city
import os
fn = 'arctic.cpt'
if not os.path.isfile(fn):
import urllib
url = 'http://soliton.vm.bytemark.co.uk/pub/cpt-city/arendal/arctic.cpt'
urllib.urlretrieve(url, fn)
#Load with positions calibrated
cbar1.colourmap(lavavu.loadCPT(fn))
#Load colour data only
cbar2.colourmap(lavavu.loadCPT(fn, positions=False))
lv.display(resolution=[640,90], transparent=True)
except:
pass
**Predefined maps**
There are a number of colour maps available for convenience which can be
accessed by passing their name instead of a list of colours when
creating a colour map.
.. code:: ipython3
#Get the list of colormap names
#suggest: lv.colourmaps.(names)
maps = lv.defaultcolourmaps()
print(maps)
.. parsed-literal::
['diverge', 'isolum', 'isorainbow', 'cubelaw', 'cubelaw2', 'smoothheat', 'coolwarm', 'spectral', 'drywet', 'elevation', 'dem1', 'dem2', 'dem3', 'dem4', 'ocean', 'bathy', 'seafloor', 'abyss', 'ibcso', 'gebco', 'topo', 'sealand', 'nighttime', 'world', 'geo', 'terra', 'relief', 'globe', 'earth', 'etopo1', 'cubhelix', 'hot', 'cool', 'copper', 'gray', 'split', 'polar', 'red2green', 'paired', 'categorical', 'haxby', 'jet', 'panoply', 'no_green', 'wysiwyg', 'seis', 'rainbow', 'nih']
| The first eight maps are selected to vary evenly in luminance to
reduce banding artifacts
| Following these are further maps inspired by the default colour tables
from the `Generic Mapping Tools `__
| Those maps that have fixed colour positions included can also be
loaded without the position data by preceding the name with ‘@’
The colourmap data can be retrieved for modification as follows:
.. code:: ipython3
print(lv.defaultcolourmap('cubelaw'))
.. parsed-literal::
#440088 #831bb9 #578ee9 #3db6b6 #6ce64d #afeb56 #ffff88
| **Plot of all built in maps**
| Finally we will plot all the available built in colourmaps in
continuous and discrete modes
.. code:: ipython3
#Clear the plot and create some new colour bars
lv.clear()
#Default continuous colour bar
cbar1 = lv.colourbar(size=[0.95,15], align="top")
#Discrete colour bar with bin labels enabled
cbar2 = lv.colourbar(size=[0.95,15], align="top", binlabels=True)
.. code:: ipython3
#Plot each map in the list
for name in maps:
print(name)
#Load as continuous colourmap
cbar1.colourmap(name)
#Load as discrete colourmap
cbar2.colourmap(name, discrete=True, range=[-6,6])
lv.display(resolution=[640,90], transparent=True)
.. parsed-literal::
diverge
.. raw:: html
.. parsed-literal::
isolum
.. raw:: html
.. parsed-literal::
isorainbow
.. raw:: html
.. parsed-literal::
cubelaw
.. raw:: html
.. parsed-literal::
cubelaw2
.. raw:: html
.. parsed-literal::
smoothheat
.. raw:: html
.. parsed-literal::
coolwarm
.. raw:: html
.. parsed-literal::
spectral
.. raw:: html
.. parsed-literal::
drywet
.. raw:: html
.. parsed-literal::
elevation
.. raw:: html
.. parsed-literal::
dem1
.. raw:: html
.. parsed-literal::
dem2
.. raw:: html
.. parsed-literal::
dem3
.. raw:: html
.. parsed-literal::
dem4
.. raw:: html
.. parsed-literal::
ocean
.. raw:: html
.. parsed-literal::
bathy
.. raw:: html
.. parsed-literal::
seafloor
.. raw:: html
.. parsed-literal::
abyss
.. raw:: html
.. parsed-literal::
ibcso
.. raw:: html
.. parsed-literal::
gebco
.. raw:: html
.. parsed-literal::
topo
.. raw:: html
.. parsed-literal::
sealand
.. raw:: html
.. parsed-literal::
nighttime
.. raw:: html
.. parsed-literal::
world
.. raw:: html
.. parsed-literal::
geo
.. raw:: html
.. parsed-literal::
terra
.. raw:: html
.. parsed-literal::
relief
.. raw:: html
.. parsed-literal::
globe
.. raw:: html
.. parsed-literal::
earth
.. raw:: html
.. parsed-literal::
etopo1
.. raw:: html
.. parsed-literal::
cubhelix
.. raw:: html
.. parsed-literal::
hot
.. raw:: html
.. parsed-literal::
cool
.. raw:: html
.. parsed-literal::
copper
.. raw:: html
.. parsed-literal::
gray
.. raw:: html
.. parsed-literal::
split
.. raw:: html
.. parsed-literal::
polar
.. raw:: html
.. parsed-literal::
red2green
.. raw:: html
.. parsed-literal::
paired
.. raw:: html
.. parsed-literal::
categorical
.. raw:: html
.. parsed-literal::
haxby
.. raw:: html
.. parsed-literal::
jet
.. raw:: html
.. parsed-literal::
panoply
.. raw:: html
.. parsed-literal::
no_green
.. raw:: html
.. parsed-literal::
wysiwyg
.. raw:: html
.. parsed-literal::
seis
.. raw:: html
.. parsed-literal::
rainbow
.. raw:: html
.. parsed-literal::
nih
.. raw:: html
