sequence logos in matplotlib: aligning xticks

Question

I am trying to draw sequence logos using matplotlib. The entire code is available on gist

The relevant portion is:

class Scale(matplotlib.patheffects         


        

Answer 1

I simplified the code to make it generalizable to DPI/screen coordinates. The major change is that it draws the first character and then measures its screen width/height and then uses those parameters for the rest.

from matplotlib.patheffects import RendererBase
from matplotlib.transforms import offset_copy
from matplotlib.patches import Rectangle

class Scale(RendererBase):
    def __init__(self, sx, sy=None):
        self._sx = sx
        self._sy = sy

    def draw_path(self, renderer, gc, tpath, affine, rgbFace):
        affine = affine.identity().scale(self._sx, self._sy) + affine
        renderer.draw_path(gc, tpath, affine, rgbFace)

iupac = "XACMGRSVTWYHKDBN"

iupac_colors = ['black'] * 16
iupac_colors[1<<0] = 'blue'
iupac_colors[1<<1] = 'red'
iupac_colors[1<<2] = 'green'
iupac_colors[1<<3] = 'gold'     

fig, ax = plt.subplots()
fig.set_size_inches(4, 1)


w=25
ax.set_xlim(0, w)

xoffset=int((w-pwm.shape[1])/2)

wscale=1
for i in range(pwm.shape[1]):
    yshift = 0
    for j in range(4):
        base=iupac[(1<