Histogram of Dates by Day of Year -- https://stackoverflow.com/questions/62391648/

plot_by_day.py

from datetime import datetime, timedelta
import random

import matplotlib.pyplot as plt
import matplotlib.dates as dates


def make_data():
    random.seed(0)  # Make it repeatable
    s = datetime(2020, 1, 1)  # Pick a leap year!
    days = [s + timedelta(days=i) for i in range(366)]
    values = [random.randint(5, 30) for _ in days]
    return days, values


def plot_by_day(days, values):
    plt.style.use('Solarize_Light2')
    fig = plt.figure(figsize=(20, 4), dpi=150)
    ax = fig.add_subplot(111)
    # add space for a second x-axis (not sure what a good value for bottom is)
    fig.subplots_adjust(bottom=0.2)

    ax.bar(days, values, align='edge', width=1, linewidth=0, alpha=.8)
    ax2 = ax.twiny()

    # Time hierarchy: Month / day (1/15), then day (8/22)
    # Axis 2: Month
    ax2.xaxis.set_major_locator(dates.MonthLocator())
    ax2.xaxis.set_major_formatter(dates.DateFormatter('%b'))

    # Axis 1: Major (Days 1/15)
    ax.xaxis.set_major_locator(dates.DayLocator(bymonthday=[1, 15]))
    ax.xaxis.set_major_formatter(dates.DateFormatter('%-d'))
    ax.xaxis.set_tick_params(labelsize=8)
    ax.set_xlim(days[0], days[-1] + timedelta(hours=23))

    # Axis 1: Minor (Days 8 / 22)
    ax.xaxis.set_minor_locator(dates.DayLocator(bymonthday=[8, 22]))
    ax.xaxis.set_minor_formatter(dates.DateFormatter('%-d'))
    ax.xaxis.set_tick_params(which="minor", labelsize=5)

    # This is a lot of work just to move the second axis to the bottom
    # of the chart (we made room for it with subplots_adjust above)
    ax2.set_xlim(ax.get_xlim())
    ax2.spines["bottom"].set_position(("axes", -0.05))  # position of text.
    ax2.spines["bottom"].set_visible(False)  # don't show the axis line
    ax2.xaxis.set_ticks_position("bottom")
    ax2.xaxis.set_label_position("bottom")
    ax2.xaxis.set_tick_params(grid_visible=False)  # already have ax's grid
    for label in ax2.xaxis.get_ticklabels():
        label.set_horizontalalignment('left')
    # ax2.patch.set_visible(False)
    # for sp in ax2.spines.values(): sp.set_visible(False)

    # just go with it and use title twice.
    ax.set_title("Day of Year Chart")
    ax.set_title(
        "{:,} data points".format(len(values)),
        loc='right', fontsize=8, color='gray')
    ax2.set_xlabel("Date")
    ax.set_ylabel("Count")

    fig.savefig(
        'plot_by_day.png',
        facecolor=fig.get_facecolor(),
        edgecolor='none'
    )


def main():
    days, values = make_data()
    plot_by_day(days, values)


if __name__ == '__main__':
    main()

Output looks like this: