heatmap
Calculate RGB value for a range of values to create heat map
def rgb(minimum, maximum, value): minimum, maximum = float(minimum), float(maximum) ratio = 2 * (value-minimum) / (maximum – minimum) b = int(max(0, 255*(1 – ratio))) r = int(max(0, 255*(ratio – 1))) g = 255 – b – r return r, g, b
How to understand Seaborn’s heatmap annotation format
There isn’t a clear and quick answer to this at the top of search engine results so I provide simple examples here: .1e = scientific notation with 1 decimal point (standard form) .2f = 2 decimal places .3g = 3 significant figures .4% = percentage with 4 decimal places A more detailed explanation on the … Read more
First and last row cut in half of heatmap plot
Unfortunately matplotlib 3.1.1 broke seaborn heatmaps; and in general inverted axes with fixed ticks. This is fixed in the current development version; you may hence revert to matplotlib 3.1.0 use matplotlib 3.1.2 or higher set the heatmap limits manually (ax.set_ylim(bottom, top) # set the ylim to bottom, top)
Heatmap with text in each cell with matplotlib’s pyplot
You need to add all the text by calling axes.text(), here is an example: import numpy as np import matplotlib.pyplot as plt title = “ROC’s AUC” xlabel= “Timeshift” ylabel=”Scales” data = np.random.rand(8,12) plt.figure(figsize=(12, 6)) plt.title(title) plt.xlabel(xlabel) plt.ylabel(ylabel) c = plt.pcolor(data, edgecolors=”k”, linewidths=4, cmap=’RdBu’, vmin=0.0, vmax=1.0) def show_values(pc, fmt=”%.2f”, **kw): from itertools import izip pc.update_scalarmappable() ax … Read more
gnuplot 2D polar plot with heatmap from 3D dataset – possible?
The image plotting works only for equally distributed rectangular grids, just like any bitmap image is arranged. Otherwise you must use splot with pm3d. The set grid polar works only for 2D, so you must use multiplot to overlay your heatmap with the polar grid. Here a, quite lengthy, example to show you how it … Read more
Overlapping yticklabels: Is it possible to control cell size of heatmap in seaborn?
The only way to make more room for the labels is to increase the height of the matrix. The only other option would be to decrease the font size, but I guess that’s not what you want. So you can compute the ideal figure height based on the number of rows in the matrix and … Read more
Superimpose heatmap on a base image OpenCV Python
Updated Answer — 29th April, 2022. After the repeated comments I have decided to update this post with a better visualization. Consider the following image: img = cv2.imread(‘image_path’) I obtained a binary image after performing binary threshold on the a-channel of the LAB converted image: lab = cv2.cvtColor(img, cv2.COLOR_BGR2LAB) a_component = lab[:,:,1] th = cv2.threshold(a_component,140,255,cv2.THRESH_BINARY)[1] … Read more
Python package to plot two heatmaps in one (split each square into two triangles)
plt.tripcolor colors a mesh of triangles similar to how plt.pcolormesh colors a rectangular mesh. Also similar to pcolormesh, care has to be taken that there is one row and one column of vertices less than there are triangles. Furthermore, the arrays need to be made 1D (np.ravel). All this renumbering to 1D can be a … Read more