pythonmatplotliblabelhistogramwhite-labelling

python labelling new data points in a histogram


I am currently using this code to draw a histogram.

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.ticker import FormatStrFormatter

data = np.random.randn(82)
fig, ax = plt.subplots()
counts, bins, patches = ax.hist(data, facecolor='yellow', edgecolor='gray')

# Set the ticks to be at the edges of the bins.
ax.set_xticks(bins)
# Set the xaxis's tick labels to be formatted with 1 decimal place...
ax.xaxis.set_major_formatter(FormatStrFormatter('%0.1f'))

# Change the colors of bars at the edges...
twentyfifth, seventyfifth = np.percentile(data, [25, 75])
for patch, rightside, leftside in zip(patches, bins[1:], bins[:-1]):
    if rightside < twentyfifth:
        patch.set_facecolor('green')
    elif leftside > seventyfifth:
        patch.set_facecolor('red')

# Label the raw counts and the percentages below the x-axis...
bin_centers = 0.5 * np.diff(bins) + bins[:-1]
for count, x in zip(counts, bin_centers):
    # Label the raw counts
    ax.annotate(str(count), xy=(x, 0), xycoords=('data', 'axes fraction'),
        xytext=(0, -18), textcoords='offset points', va='top', ha='center')

    # Label the percentages
    percent = '%0.0f%%' % (100 * float(count) / counts.sum())
    ax.annotate(percent, xy=(x, 0), xycoords=('data', 'axes fraction'),
        xytext=(0, -32), textcoords='offset points', va='top', ha='center')


# Give ourselves some more room at the bottom of the plot
plt.subplots_adjust(bottom=0.15)
plt.show()

I want to add x marks (labelled with "orange", "apple", "pineapple") of a given histogram x-axis value on the histogram as shown: Example

How should I do so?

The x marks do not have a y value.


Solution

  • All stays the same except for these lines:

    ...
    # Change the colors of bars at the edges...
    left = []
    right = []
    twentyfifth, seventyfifth = np.percentile(data, [25, 75])
    for patch, rightside, leftside in zip(patches, bins[1:], bins[:-1]):
        if rightside < twentyfifth:
            patch.set_facecolor('green')
            left.append(leftside)
    
        elif leftside > seventyfifth:
            patch.set_facecolor('red')
            right.append(rightside)
    
    ax.text(left[int(len(left)/2)], 1, 'orange\n    x')
    ax.text(right[0], 1, 'pineapple\n       x')
    ax.text((left[int(len(left)/2)] + right[0]) / 2, 1, 'apple\n   x')
    
    # Label the raw counts and the percentages below the x-axis...
    bin_centers = 0.5 * np.diff(bins) + bins[:-1]
    ...
    

    Output:

    enter image description here

    ---edit---

    OP added the data and asked for an edit.

    The code from OP in the question stays as it is, the following lines are to be added after.

    data = {'product_name': ['laptop', 'printer', 'tablet', 'desk', 'chair'],'price': [2, 0.1, 2.4, 2.2, 1]}
    ax.scatter(data['price'], [1]*len(data['price']), zorder=2, marker='x', c='k')
    for i in range(len(data['price'])):
        ax.text(data['price'][i]-0.2, 1.5, f"{data['product_name'][i]}")
    

    Output:

    enter image description here

    The annotations are overlapping, but this is expected due to the x-values given by the OP (very close to each other).