Matplotlib Multi-colored Title (Text) - in practice - python-3.x

Question

There is an example here for how to create a multi-colored text title.
However, I want to apply this to a plot that already has a figure in it.
For example, if I apply it to this (same code as with the example minus a few extras and with another figure)...:
plt.rcdefaults()
import matplotlib.pyplot as plt
%matplotlib inline
from matplotlib import transforms
fig = plt.figure(figsize=(4,3), dpi=300)
def rainbow_text(x,y,ls,lc,**kw):
t = plt.gca().transData
fig = plt.gcf()
plt.show()
#horizontal version
for s,c in zip(ls,lc):
text = plt.text(x,y," "+s+" ",color=c, transform=t, **kw)
text.draw(fig.canvas.get_renderer())
ex = text.get_window_extent()
t = transforms.offset_copy(text._transform, x=ex.width, units='dots')
plt.figure()
rainbow_text(0.5,0.5,"all unicorns poop rainbows ! ! !".split(),
['red', 'orange', 'brown', 'green', 'blue', 'purple', 'black'],
size=40)
...the result is 2 plots with the title enlarged.
This sort of makes sense to me because I'm using plt. two times.
But how do I integrate it so that it only refers to the first instance of plt. in creating the title?
Also, about this line:
t = transforms.offset_copy(text._transform, x=ex.width, units='dots')
I notice it can alter the spacing between words, but when I play with the values of x, results are not predictable (spacing is inconsistent between words).
How can I meaningfully adjust that value?
And finally, where it says "units='dots'", what are the other options? Are 'dots' 1/72nd of an inch (and is that the default for Matplotlib?)?
How can I convert units from dots to inches?
Thanks in advance!

Answer 1

In fact the bounding box of the text comes in units unlike the ones used, for example, in scatterplot. Text is a different kind of object that gets somehow redraw if you resize the window or change the ratio. By having a stabilized window you can ask the coordinates of the bounding box in plot units and build your colored text that way:
a = "all unicorns poop rainbows ! ! !".split()
c = ['red', 'orange', 'brown', 'green', 'blue', 'purple', 'black']
f = plt.figure(figsize=(4,3), dpi=120)
ax = f.add_subplot(111)
r = f.canvas.get_renderer()
space = 0.1
w = 0.5
counter = 0
for i in a:
t = ax.text(w, 1.2, a[counter],color=c[counter],fontsize=12,ha='left')
transf = ax.transData.inverted()
bb = t.get_window_extent(renderer=f.canvas.renderer)
bb = bb.transformed(transf)
w = w + bb.xmax-bb.xmin + space
counter = counter + 1
plt.ylim(0.5,2.5)
plt.xlim(0.6,1.6)
plt.show()
, which results in:
This, however, is still not ideal since you need to keep controlling the size of your plot axis to obtain the correct spaces between words. This is somewhat arbitrary but if you manage to do your program with such a control it's feasible to use plot units to achieve your intended purpose.
ORIGINAL POST:
plt. is just the call to the library. In truth you are creating an instance of plt.figure in the global scope (so it can be seen in locally in the function). Due to this you are overwriting the figure because you use the same name for the variable (so it's just one single instance in the end). To solve this try controlling the names of your figure instances. For example:
import matplotlib.pyplot as plt
#%matplotlib inline
from matplotlib import transforms
fig = plt.figure(figsize=(4,3), dpi=300)
#plt.show(fig)
def rainbow_text(x,y,ls,lc,**kw):
t = plt.gca().transData
figlocal = plt.gcf()
#horizontal version
for s,c in zip(ls,lc):
text = plt.text(x,y," "+s+" ",color=c, transform=t, **kw)
text.draw(figlocal.canvas.get_renderer())
ex = text.get_window_extent()
t = transforms.offset_copy(text._transform, x=ex.width, units='dots')
plt.show(figlocal) #plt.show((figlocal,fig))
#plt.figure()
rainbow_text(0.5,0.5,"all unicorns poop rainbows ! ! !".split(),
['red', 'orange', 'brown', 'green', 'blue', 'purple', 'black'],
size=40,)
I've commented several instructions but notice I give a different name for the figure local to the function (figlocal). Also notice that in my examples of show I control directly which figure should be shown.
As for your other questions notice you can use other units as can be seen in the function documentation:
Return a new transform with an added offset.
args:
trans is any transform
kwargs:
fig is the current figure; it can be None if units are 'dots'
x, y give the offset
units is 'inches', 'points' or 'dots'
EDIT: Apparently there's some kind of problem with the extents of the bounding box for text that does not give the correct width of the word and thus the space between words is not stable. My advise is to use the latex functionality of Matplotlib to write the colors in the same string (so only one call of plt.text). You can do it like this:
import matplotlib
import matplotlib.pyplot as plt
matplotlib.use('pgf')
from matplotlib import rc
rc('text',usetex=True)
rc('text.latex', preamble=r'\usepackage{color}')
a = "all unicorns poop rainbows ! ! !".split()
c = ['red', 'orange', 'brown', 'green', 'blue', 'purple', 'black']
st = ''
for i in range(len(a)):
st = st + r'\textcolor{'+c[i]+'}{'+a[i]+'}'
plt.text(0.5,0.5,st)
plt.show()
This however is not an ideal solution. The reason is that you need to have Latex installed, including the necessary packages (notice I'm using the color package). Take a look at Yann answer in this question: Partial coloring of text in matplotlib

Answer 2

#armatita: I think your answer actually does what I need. I thought I needed display coordinates instead, but it looks like I can just use axis 1 coordinates, if that's what this is (I'm planning on using multiple axes via subplot2grid). Here's an example:
import matplotlib.pyplot as plt
%matplotlib inline
dpi=300
f_width=4
f_height=3
f = plt.figure(figsize=(f_width,f_height), dpi=dpi)
ax1 = plt.subplot2grid((100,115), (0,0), rowspan=95, colspan=25)
ax2 = plt.subplot2grid((100,115), (0,30), rowspan=95, colspan=20)
ax3 = plt.subplot2grid((100,115), (0,55), rowspan=95, colspan=35)
ax4 = plt.subplot2grid((100,115), (0,95), rowspan=95, colspan=20)
r = f.canvas.get_renderer()
t = ax1.text(.5, 1.1, 'a lot of text here',fontsize=12,ha='left')
space=0.1
w=.5
transf = ax1.transData.inverted()
bb = t.get_window_extent(renderer=f.canvas.renderer)
bb = bb.transformed(transf)
e = ax1.text(.5+bb.width+space, 1.1, 'text',fontsize=12,ha='left')
print(bb)
plt.show()
I'm not sure what you mean about controlling the axis size, though. Are you referring to using the code in different environments or exporting the image in different sizes? I plan on having the image used in the same environment and in the same size (per instance of using this approach), so I think it will be okay. Does my logic make sense? I have a weak grasp on what's really going on, so I hope so. I would use it with a function (via splitting the text) like you did, but there are cases where I need to split on other characters (i.e. when a word in parentheses should be colored, but not the parentheses). Maybe I can just put a delimiter in there like ','? I think I need a different form of .split() because it didn't work when I tried it.
At any rate, if I can implement this across all of my charts, it will save me countless hours. Thank you so much!

Answer 3

Here is an example where there are 2 plots and 2 instances of using the function for posterity:
import matplotlib.pyplot as plt
%matplotlib inline
dpi=300
f_width=4
f_height=3
f = plt.figure(figsize=(f_width,f_height), dpi=dpi)
ax1 = plt.subplot2grid((100,60), (0,0), rowspan=95, colspan=30)
ax2 = plt.subplot2grid((100,60), (0,30), rowspan=95, colspan=30)
f=f #Name for figure
string = str("Group 1 ,vs. ,Group 2 (,sub1,) and (,sub2,)").split(',')
color = ['black','red','black','green','black','blue','black']
xpos = .5
ypos = 1.2
axis=ax1
#No need to include space if incuded between delimiters above
#space = 0.1
def colortext(f,string,color,xpos,ypos,axis):
#f=figure object name (i.e. fig, f, figure)
r = f.canvas.get_renderer()
counter = 0
for i in string:
t = axis.text(xpos, ypos, string[counter],color=color[counter],fontsize=12,ha='left')
transf = axis.transData.inverted()
bb = t.get_window_extent(renderer=f.canvas.renderer)
bb = bb.transformed(transf)
xpos = xpos + bb.xmax-bb.xmin
counter = counter + 1
colortext(f,string,color,xpos,ypos,axis)
string2 = str("Group 1 part 2 ,vs. ,Group 2 (,sub1,) and (,sub2,)").split(',')
ypos2=1.1
colortext(f,string2,color,xpos,ypos2,axis)
plt.show()