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[Bug]: Incorrect rendering of Abugida fonts on Matplotlib visualization #29357

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nik9hil opened this issue Dec 20, 2024 · 1 comment
Open

[Bug]: Incorrect rendering of Abugida fonts on Matplotlib visualization #29357

nik9hil opened this issue Dec 20, 2024 · 1 comment
Milestone
v3.11.0

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@nik9hil
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nik9hil commented Dec 20, 2024

Bug summary

While trying to plot a heatmap, with labels in Devanagari script, I observe that words with vowel markers that come before the consonant are being rendered incorrectly in the plot.

image

The issue seems to lie only within the plot and is correctly rendered outside the plot in other Jupyter notebook output cells. I have imported Noto Serif Devanagari Thin of format ".ttf" in the font_manager of matplotlib.

Code for reproduction

#-------------------------------------Importing font file--------------------------------------------
import matplotlib.pyplot as plt
from matplotlib import font_manager

font_path = r'../NotoSerifDevanagari-Thin.ttf'  #Font Download URL https://fonts.google.com/noto/specimen/Noto+Serif+Devanagari
font_manager.fontManager.addfont(font_path)
prop = font_manager.FontProperties(fname=font_path)

plt.rcParams['font.family'] = 'sans-serif'
plt.rcParams['font.sans-serif'] = prop.get_name()


#---------------------------------------Printing the Heatmap------------------------------------------

cols = ['कंऊ', 'कंकन', 'कंकाल', 'कंग', 'कंगण', 'कंगणयाठ', 'कंगणा', 'कंगणी',
       'कंगणु', 'कंगयारी', 'कंगर', 'कंगरमाला', 'कंगला', 'कंगाळ',
       'कंगावणो', 'कंगियारी', 'कंगूरा', 'कंगोयर', 'कंगड़ोणा', 'कंघू']

import seaborn as sns

distances = [[ 1.00000012,  0.07712191,  0.14661103, -0.04143704,  0.53648712,
         0.33697583,  0.53648712,  0.51686014,  0.38120874,  0.50693332,
         0.45912105,  0.39092736,  0.37029334,  0.48355384,  0.08494762,
         0.2027287 ,  0.22532   , -0.13099329,  0.21541182,  0.2619344 ],
       [ 0.07712191,  1.        ,  0.27505046,  0.02465715,  0.19377662,
         0.1261098 ,  0.19377662,  0.1506419 ,  0.35335953,  0.20175425,
         0.24165124,  0.28307295,  0.16849031,  0.0239366 ,  0.07874829,
         0.13574625,  0.20279602,  0.13992496,  0.07440536,  0.29719737],
       [ 0.14661103,  0.27505046,  1.        , -0.04620013,  0.33248773,
         0.15105981,  0.33248773,  0.22782895,  0.32314968,  0.16231962,
         0.33643136,  0.33366867,  0.06132669,  0.00628519,  0.31157723,
         0.32549456,  0.24985954,  0.08681663, -0.0043968 ,  0.30289415],
       [-0.04143704,  0.02465715, -0.04620013,  1.        , -0.03092548,
         0.06609477, -0.03092548, -0.13675212, -0.02324197, -0.24876945,
        -0.19765455, -0.09264191,  0.10586093, -0.03386144, -0.07041141,
        -0.16070572, -0.11320979,  0.05005207,  0.06435453, -0.04384374],
       [ 0.53648712,  0.19377662,  0.33248773, -0.03092548,  1.        ,
         0.29916139,  1.        ,  0.65163825,  0.72046704,  0.55254239,
         0.57694138,  0.62017921,  0.42146252,  0.40582417,  0.13931256,
         0.42310567,  0.34080061,  0.02983071,  0.21334639,  0.47694966],
       [ 0.33697583,  0.1261098 ,  0.15105981,  0.06609477,  0.29916139,
         1.        ,  0.29916139,  0.54745869,  0.28604334,  0.39199968,
         0.36999825,  0.2213295 ,  0.26273593,  0.39979477,  0.15303509,
         0.33649553,  0.09807743,  0.05601585,  0.2305386 ,  0.40991256],
       [ 0.53648712,  0.19377662,  0.33248773, -0.03092548,  1.        ,
         0.29916139,  1.        ,  0.65163825,  0.72046704,  0.55254239,
         0.57694138,  0.62017921,  0.42146252,  0.40582417,  0.13931256,
         0.42310567,  0.34080061,  0.02983071,  0.21334639,  0.47694966],
       [ 0.51686014,  0.1506419 ,  0.22782895, -0.13675212,  0.65163825,
         0.54745869,  0.65163825,  1.        ,  0.71716835,  0.63264708,
         0.62838955,  0.47028607,  0.33207874,  0.47275523,  0.16827085,
         0.50378844,  0.26850763, -0.06614359,  0.25800855,  0.56002025],
       [ 0.38120874,  0.35335953,  0.32314968, -0.02324197,  0.72046704,
         0.28604334,  0.72046704,  0.71716835,  1.        ,  0.50603543,
         0.5059674 ,  0.52531186,  0.29890772,  0.30439026,  0.31332371,
         0.46341207,  0.33670898,  0.1210591 ,  0.1456821 ,  0.45291205],
       [ 0.50693332,  0.20175425,  0.16231962, -0.24876945,  0.55254239,
         0.39199968,  0.55254239,  0.63264708,  0.50603543,  1.        ,
         0.55836697,  0.25994718,  0.31039424,  0.36613216,  0.24675051,
         0.465611  ,  0.23443568,  0.01218331,  0.37018659,  0.45373405],
       [ 0.45912105,  0.24165124,  0.33643136, -0.19765455,  0.57694138,
         0.36999825,  0.57694138,  0.62838955,  0.5059674 ,  0.55836697,
         1.        ,  0.44948247,  0.25360835,  0.39044196,  0.23445548,
         0.59344035,  0.56251523, -0.01464187,  0.22015723,  0.61909768],
       [ 0.39092736,  0.28307295,  0.33366867, -0.09264191,  0.62017921,
         0.2213295 ,  0.62017921,  0.47028607,  0.52531186,  0.25994718,
         0.44948247,  1.        ,  0.3531896 ,  0.22887981,  0.06463467,
         0.3665741 ,  0.42415992,  0.08162159,  0.08619286,  0.39534383],
       [ 0.37029334,  0.16849031,  0.06132669,  0.10586093,  0.42146252,
         0.26273593,  0.42146252,  0.33207874,  0.29890772,  0.31039424,
         0.25360835,  0.3531896 ,  1.        ,  0.76107077, -0.00676973,
         0.24680215,  0.09632001,  0.00772719,  0.178872  ,  0.29167667],
       [ 0.48355384,  0.0239366 ,  0.00628519, -0.03386144,  0.40582417,
         0.39979477,  0.40582417,  0.47275523,  0.30439026,  0.36613216,
         0.39044196,  0.22887981,  0.76107077,  1.        ,  0.00392713,
         0.17269458,  0.0984515 , -0.09089949,  0.12039699,  0.30054512],
       [ 0.08494762,  0.07874829,  0.31157723, -0.07041141,  0.13931256,
         0.15303509,  0.13931256,  0.16827085,  0.31332371,  0.24675051,
         0.23445548,  0.06463467, -0.00676973,  0.00392713,  1.00000012,
         0.31029389,  0.00211672,  0.10704701,  0.04611979,  0.17345914],
       [ 0.2027287 ,  0.13574625,  0.32549456, -0.16070572,  0.42310567,
         0.33649553,  0.42310567,  0.50378844,  0.46341207,  0.465611  ,
         0.59344035,  0.3665741 ,  0.24680215,  0.17269458,  0.31029389,
         1.        ,  0.40896827,  0.10605786,  0.21322685,  0.62610233],
       [ 0.22532   ,  0.20279602,  0.24985954, -0.11320979,  0.34080061,
         0.09807743,  0.34080061,  0.26850763,  0.33670898,  0.23443568,
         0.56251523,  0.42415992,  0.09632001,  0.0984515 ,  0.00211672,
         0.40896827,  1.        ,  0.08140745,  0.10477526,  0.31258686],
       [-0.13099329,  0.13992496,  0.08681663,  0.05005207,  0.02983071,
         0.05601585,  0.02983071, -0.06614359,  0.1210591 ,  0.01218331,
        -0.01464187,  0.08162159,  0.00772719, -0.09089949,  0.10704701,
         0.10605786,  0.08140745,  1.        ,  0.00525283,  0.08305563],
       [ 0.21541182,  0.07440536, -0.0043968 ,  0.06435453,  0.21334639,
         0.2305386 ,  0.21334639,  0.25800855,  0.1456821 ,  0.37018659,
         0.22015723,  0.08619286,  0.178872  ,  0.12039699,  0.04611979,
         0.21322685,  0.10477526,  0.00525283,  1.        ,  0.08586092],
       [ 0.2619344 ,  0.29719737,  0.30289415, -0.04384374,  0.47694966,
         0.40991256,  0.47694966,  0.56002025,  0.45291205,  0.45373405,
         0.61909768,  0.39534383,  0.29167667,  0.30054512,  0.17345914,
         0.62610233,  0.31258686,  0.08305563,  0.08586092,  1.        ]]

fig, ax = plt.subplots(figsize=(20, 20))

s = sns.heatmap(distances, square=True, annot=True, cbar=False, cmap='Blues', ax=ax)

s.set_yticklabels(cols)
s.set_xticklabels(cols)

hfont = {'fontname':'Helvetica'}
plt.xlabel('Words', **hfont)
plt.ylabel('Words', **hfont)

plt.xticks(rotation=90)
plt.yticks(rotation=0) 

plt.rcParams.update({'font.size': 20})
plt.show()

Actual outcome

image

Expected outcome

In the expected outcome, the highlighted label in the bug summary image should be rendered as कंगियारी. In the current output it is being rendered like कंगयिारी which is wrong.

Additional information

I observe that words with vowel markers that come before the consonant are being rendered incorrectly in the plot. This makes me believe that this might be due to some old font engine which is being used in matplotlib to render Unicode characters.

Operating system

Windows

Matplotlib Version

3.4.3

Matplotlib Backend

module://matplotlib_inline.backend_inline

Python version

3.9.7

Jupyter version

6.4.5

Installation

pip
@tacaswell
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This is a known limitation which has on-going work to address.

attn @QuLogic .

@tacaswell tacaswell added this to the v3.11.0 milestone Dec 20, 2024
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@tacaswell @nik9hil