python labelling new data points in a histogram

Question

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.

Karina · Accepted Answer · 2021-10-14T09:51:38.400

0

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:

---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:

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

edited Oct 14 '21 at 09:51

answered Oct 13 '21 at 06:53

Karina

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thank you for the answer! But it isnt what I am exactly looking for. So I have a dataframe `data = {'product_name': ['laptop', 'printer', 'tablet', 'desk', 'chair'],'price': [1200, 150, 300, 450, 200]}` The column "price" would be the x that I want to plot on top of the histogram with, while the column "product name" would be the label that I want each point to be labelled with. @Karina – inic72 Oct 14 '21 at 04:34
I don't get it. If your ``x`` values are in the range of ``150`` to ``1200``, where should it be? You plot ``xlim`` is basically just ``-2,2`` to ``2,6`` for example. – Karina Oct 14 '21 at 05:53
`data = {'product_name': ['laptop', 'printer', 'tablet', 'desk', 'chair'],'price': [2, 0.1, 2.4, 2.2, 1]}` apologies for the confusion. I have revised the dataframe, what will the code be like in the case of this. – inic72 Oct 14 '21 at 06:06
just so you know, that's totally different than what is shown in your question. It would be much more productive if you had this information in the question. – Karina Oct 14 '21 at 09:47
The annotations are overlapping, but I hope you expected this much due to the nature of your data. An alternative would be dynamically changing the position of your annotation label. But that is not within this question. – Karina Oct 14 '21 at 09:53

python labelling new data points in a histogram

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