How to convert y-axis tick label numbers to letters

Question

For the code:

import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns

data = list(map(lambda n:str(n), np.random.choice(np.arange(1,50), 1000)))
fig, ax = plt.subplots(1,1)
sns.countplot(y=data,ax=ax)
ax.set_yticklabels(ax.get_yticklabels(), fontsize=5)
plt.show()

I got the plot below. The y-axis is string type 1~2 digit integers. I want to convert them to letters like

1->AL, 2->AK, 4->AZ, 5->AR, ...

I tried using ax.set_yticks(ylabel, converted ylabel), but it did not work. How can I do that?

Answer 1

You need to create a function that converts numbers to the desired letter representation.

import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns

# Number to desired letters (can customize this function)
def number_to_letters(n):
    first_letter = chr(64 + (n // 26) + 1)  # 'A' is 65 in ASCII
    second_letter = chr(64 + (n % 26) + 1)

    return first_letter + second_letter

data = list(map(lambda n: str(n), np.random.choice(np.arange(1, 50), 1000)))
# mapping numbers to letters
data_letters = [number_to_letters(int(d)) for d in data]

fig, ax = plt.subplots(1, 1)
sns.countplot(y=data_letters, ax=ax, order=sorted(set(data_letters)))
ax.set_yticklabels(sorted(set(data_letters)), fontsize=5)
plt.show()

Answer 2

In addition to @Yuri's answer, I just wanted to put another answer that also worked for me. This is to get the label (a list of plt.Text objects) by get_yticklabels(), and to pull information from it by plt.Text.get_text() and plt.Text.get_position().

import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
def number_to_letters(n):
    n = int(n)
    first_letter = chr(64 + (n // 26) + 1)  # 'A' is 65 in ASCII
    second_letter = chr(64 + (n % 26) + 1)
    return first_letter + second_letter
data = list(map(lambda n:str(n), np.random.choice(np.arange(1,50), 1000)))
fig,ax = plt.subplots(1,1)
sns.countplot(y=data,ax=ax)
new_label = []
for t in ax.get_yticklabels():
    txt = number_to_letters(t.get_text())
    loc = t.get_position()
    new_label.append(plt.Text(position=loc,text=txt))
ax.set_yticklabels(new_label,fontsize=5)
plt.show()