CODEWITHSUNDEEP
pythonpandasdataframematplotlibseaborn
actnmk
actnmk

Reputation: 166

heat map-like plot does not show the correct color

I have a dataframe df with some values from this list ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'], but sometimes not all values appear in df, for example:

df = pd.DataFrame([['a','b','c'],['b','c','e'],['a', 'e', 'f']])

I plot a heat map-like plot of df with the code below:

import seaborn as sns
import matplotlib.pyplot as plt
from matplotlib.colors import ListedColormap
import numpy as np
import pandas as pd

data = [['a','b','c'],['b','c','e'],['a', 'e', 'f']]
df = pd.DataFrame(data)

value = ['a','b','c', 'd', 'e', 'f', 'g', 'h', 'i','j']

value_to_int = {j:i for i,j in enumerate(value)}

n = len(value_to_int)     

#color for value
cmap = ['#b3e6b3', '#66cc66', '#2d862d', '#ffc299','#ff944d', '#ff6600','#ccddff','#99bbff','#4d88ff','#0044cc']

# plot
fig, ax = plt.subplots(figsize = (5, 5)) 
ax = sns.heatmap(df.replace(value_to_int), cmap=cmap,  linewidths = 0.005, annot = False) 

#add value into plot
text = df.to_numpy()
for r in range(text.shape[0]):
    for c in range(text.shape[1]):
        ax.text(c+0.5,r+0.5, text[r,c], 
                va='center',ha='center')

# modify colorbar:
colorbar = ax.collections[0].colorbar 
r = colorbar.vmax - colorbar.vmin 
colorbar.set_ticks([colorbar.vmin + r / n * (0.5 + i) for i in range(n)])
colorbar.set_ticklabels(list(value_to_int.keys()))          

plt.show()

but the plot I got is not correct, the colors do not fit with the values, for example 'c' should be dark green, on the heat map is however orange, etc.

enter image description here

how can I modify my code that it show me the correct colors? thank you so much

Upvotes: 0

Views: 653

Answers (1)

Jan Kuiken
Jan Kuiken

Reputation: 2020

Short answer: add vmin=0, vmax=9 to the sns.heatmap call. It has something to do with the scale of the graph and the colorbar.

Upvotes: 1

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