How to plot data against locale time of day only.

gistfile1.py

from matplotlib.dates import DateFormatter
from matplotlib.dates import HourLocator
from matplotlib.dates import date2num

times = pd.date_range("now", periods=24, freq="2h")

data = np.arange(len(times))

df = pd.DataFrame({"datetime": times, "data": data})

times_numbers = df.datetime.map(date2num)

df["LT"] = times_numbers % 1 + int(times_numbers[0])

fig, ax = plt.subplots()
df.plot(x="LT", y="data", style=".", ax=ax)
ax.xaxis.set_major_formatter(DateFormatter("%H:%M"))
ax.xaxis.set_major_locator(HourLocator(interval=3))
ax.grid(which="major")