matplotlib - seaborn - the numbers on the correlation plots are not readable - matplotlib

Question

The plot below shows the correlation for one column. The problem is that the numbers are not readable, because there are many columns in it.
How is it possible to show only 5 or 6 most important columns and not all of them with very low importance?
plt.figure(figsize=(20,3))
sns.heatmap(df.corr()[['price']].sort_values('price', ascending=False).iloc[1:].T, annot=True,
cmap='Spectral_r', vmax=0.9, vmin=-0.31)

Answer 1

You can limit the cells shown via .iloc[1:7]. If you also want to show the highest negative values, you could create a second plot with .iloc[-6:]. To have both together, you could use numpy's slicing function and write .iloc[np.r_[1:4, -3:0]].
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
df = pd.DataFrame(np.random.rand(7, 27), columns=['price'] + [*'abcdefghijklmnopqrstuvwxyz'])
plt.figure(figsize=(20, 3))
sns.heatmap(df.corr()[['price']].sort_values('price', ascending=False).iloc[1:7].T,
annot=True, annot_kws={'rotation':90, 'size': 20},
cmap='Spectral_r', vmax=0.9, vmin=-0.31)
plt.show()

Answer 2

annot can also be a list of labels. Using this, you can define a string matrix that you use to display the desired numbers and set the others to an empty string.
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(0)
import seaborn as sns; sns.set_theme()
import pandas as pd
from string import ascii_letters
# generate random data
rs = np.random.RandomState(33)
df = pd.DataFrame(data=rs.normal(size=(100, 26)),
columns=list(ascii_letters[26:]))
importance_index = 5 # until which idx to hide values
data = df.corr()[['A']].sort_values('A', ascending=False).iloc[1:].T
labels = data.astype(str) # make a str-copy
labels.iloc[0,:importance_index] = ' ' # mask columns that you want to hide
sns.heatmap(data, annot=labels, cmap='Spectral_r', vmax=0.9, vmin=-0.31, fmt='', annot_kws={'rotation':90})
plt.show()
The output on some random data:
This works but it has its limits, particulary with setting fmt='' (can't use it to conveniently format decimals anymore, need to do it manually now). I would also question whether your approach is even the best one to take here. I think consistency in plots is quite important. I would rather evaluate if we can't rotate the heatmap labels (I've included it above) or leave them out completely since it is technically redundant due to the color-coding. Alternatively, you could only plot the cells with the "important" values.