plotting time in python with matplotlib

Question

I have an array of timestamps in the format (HH:MM:SS.mmmmmm) and another array of floating point numbers, each corresponding to a value in the timestamp array.

Can I plot time on the x axis and the numbers on the y-axis using matplotlib? 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 anyway?

Answer 1

You must first convert your timestamps to python datetime objects (use datetime.strptime). Then use date2num to convert the dates to matplotlib format.

Plot the dates and values using plot_dates:

dates = matplotlib.dates.date2num(list_of_datetimes)
plot_dates(dates, values)

Answer 2

Look at some examples:

• date_demo1
• date_demo2

To make it only show times and not dates, pass a suitable strftime-like spec to DateFormatter.