在 python 中绘制 matplotlib 中特定格式的时间戳

Question

DD.MM_HH:MM:SS.mmmmmm in this format timestamps are given so how to process them in matplotlib in python

I was trying to, but somehow it was only accepting arrays of floats. How can I get it to plot the time? Do I have to modify the format in any way?

I tried with this

dates = matplotlib.dates.date2num(list_of_datetimes) matplotlib.pyplot.plot_date(dates, values)

But getting the following error

AttributeError: 'numpy.str_' object has no attribute 'toordinal'

Please provide the format which I should follow to parse this type of timestamp?

Answer 1

convert the strings in list_of_datetimes to datetime first:

from datetime import datetime
import matplotlib

# some example data:
list_of_datetimes = ['05.07_15:39:52.855866', '05.07_15:49:52.855866', '05.07_15:59:52.855866']
values = [1, 2, 3]

# to datetime:
dt = [datetime.strptime(s, '%d.%m_%H:%M:%S.%f') for s in list_of_datetimes]

dates = matplotlib.dates.date2num(dt)
matplotlib.pyplot.plot_date(dates, values)

An alternative could be plotting a timedelta since start on the x-axis to avoid issues with microsecond handling in matplotlib :

date = ["05.07_15:39:52.855866","05.07_15:39:52.855869","05.07_15:39:52.855988","05.07_15:39:52.855889"]
values = [1, 2, 3, 4]
dt = [datetime.strptime(s, '%d.%m_%H:%M:%S.%f') for s in date]

# to timedelta:
td = [(d-dt[0]).total_seconds() for d in dt]

matplotlib.pyplot.plot(td, values)