Histogram in matplotlib, time on x-Axis
Solution 1
Matplotlib uses its own format for dates/times, but also provides simple functions to convert which are provided in the dates
module. It also provides various Locators
and Formatters
that take care of placing the ticks on the axis and formatting the corresponding labels. This should get you started:
import random
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
# generate some random data (approximately over 5 years)
data = [float(random.randint(1271517521, 1429197513)) for _ in range(1000)]
# convert the epoch format to matplotlib date format
mpl_data = mdates.epoch2num(data)
# plot it
fig, ax = plt.subplots(1,1)
ax.hist(mpl_data, bins=50, color='lightblue')
ax.xaxis.set_major_locator(mdates.YearLocator())
ax.xaxis.set_major_formatter(mdates.DateFormatter('%d.%m.%y'))
plt.show()
Result:
Solution 2
To add to hitzg's answer, you can use AutoDateLocator
and AutoDateFormatter
to have matplotlib do the location and formatting for you:
locator = mdates.AutoDateLocator()
ax.xaxis.set_major_locator(locator)
ax.xaxis.set_major_formatter(mdates.AutoDateFormatter(locator))
four-eyes
Updated on September 29, 2020Comments
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four-eyes over 3 years
I am new to matplotlib (1.3.1-2) and I cannot find a decent place to start. I want to plot the distribution of points over time in a histogram with matplotlib.
Basically I want to plot the cumulative sum of the occurrence of a date.
date 2011-12-13 2011-12-13 2013-11-01 2013-11-01 2013-06-04 2013-06-04 2014-01-01 ...
That would make
2011-12-13 -> 2 times 2013-11-01 -> 3 times 2013-06-04 -> 2 times 2014-01-01 -> once
Since there will be many points over many years, I want to set the
start date
on myx-Axis
and theend date
, and then markn-time steps
(i.e. 1 year steps) and finally decide how manybins
there will be.How would I achieve that?