I'm using a csv file containing date time, temperature and humidity data, then loading it using pandas and matplotlib pyplot to create graphs of the data.
With some date time values I'm getting the error "ValueError: year is out of range" with valid values, with no obvious pattern.
This is for a Raspberry Pi (fully updated via apt-get) with Python 2.7.13, pandas 0.19.2 and matplotlib 2.0.0. I've reviewed countless pages via Google searches but not got anything to work yet.
Note that I'm using a day/month/year format (I'm in New Zealand).
There is no obvious difference between good and bad lines, i.e. they all look to have valid date and time values plus identical line endings (CR LF).
The code which shows the issue:
#!/usr/bin/env python2
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
filename = 'tempfile.csv'
df = pd.read_csv(filename, names=['DateTime','Air Temperature','Humidity','CPU Temperature'], header = 0)
df['DateTime'] = pd.to_datetime(df['DateTime'], format='%d/%m/%Y %H:%M', utc=None)
df.plot(kind='line',x='DateTime',y='Air Temperature')
ax = plt.gca()
ax.xaxis.set_major_formatter(mdates.DateFormatter('%H:%M'))
plt.savefig('graph.png')
plt.close()
Normally this results in graphs being generated, however some values result in errors.
Example data file:
16/06/2019 02:15,13.7,90.6,30.0
16/06/2019 02:30,13.7,92.2,30.0
16/06/2019 02:45,13.6,92.2,30.0
16/06/2019 03:00,13.4,92.0,30.0
16/06/2019 03:15,13.5,91.9,28.9
16/06/2019 03:30,13.5,91.9,28.9
Line which result in the error:
16/06/2019 03:15,13.5,91.9,28.9
A "fix" is to just modify the time component by reducing the minute value by 1, so changing the problem line to the following result avoids the error.
16/06/2019 03:14,13.5,91.9,28.9
Another "fix" is to only have either the first three lines or the last three lines of the csv data.
Another "fix" is commenting out the following line which also results in the code working, although with the loss of the x-axis formatting.
ax.xaxis.set_major_formatter(mdates.DateFormatter('%H:%M'))
The fact that this works makes me think that the error message is incorrectly pointing to a year problem.
The full error message is:
Traceback (most recent call last):
File "./max.py", line 18, in <module> plt.savefig('graph.png')
File "/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 697, in savefig res = fig.savefig(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/matplotlib/figure.py", line 1572, in savefig self.canvas.print_figure(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/matplotlib/backend_bases.py", line 2244, in print_figure **kwargs)
File "/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_agg.py", line 545, in print_png FigureCanvasAgg.draw(self)
File "/usr/lib/python2.7/dist-packages/matplotlib/backends/backend_agg.py", line 464, in draw self.figure.draw(self.renderer)
File "/usr/lib/python2.7/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper draw(artist, renderer, *args, **kwargs)
File "/usr/lib/python2.7/dist-packages/matplotlib/figure.py", line 1143, in draw renderer, self, dsu, self.suppressComposite)
File "/usr/lib/python2.7/dist-packages/matplotlib/image.py", line 139, in _draw_list_compositing_images a.draw(renderer)
File "/usr/lib/python2.7/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper draw(artist, renderer, *args, **kwargs)
File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 2409, in draw mimage._draw_list_compositing_images(renderer, self, dsu)
File "/usr/lib/python2.7/dist-packages/matplotlib/image.py", line 139, in _draw_list_compositing_images a.draw(renderer)
File "/usr/lib/python2.7/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper draw(artist, renderer, *args, **kwargs)
File "/usr/lib/python2.7/dist-packages/matplotlib/axis.py", line 1136, in draw ticks_to_draw = self._update_ticks(renderer)
File "/usr/lib/python2.7/dist-packages/matplotlib/axis.py", line 969, in _update_ticks tick_tups = [t for t in self.iter_ticks()]
File "/usr/lib/python2.7/dist-packages/matplotlib/axis.py", line 916, in iter_ticks for i, val in enumerate(majorLocs)]
File "/usr/lib/python2.7/dist-packages/matplotlib/dates.py", line 466, in __call__ dt = num2date(x, self.tz)
File "/usr/lib/python2.7/dist-packages/matplotlib/dates.py", line 401, in num2date return _from_ordinalf(x, tz)
File "/usr/lib/python2.7/dist-packages/matplotlib/dates.py", line 254, in _from_ordinalf dt = datetime.datetime.fromordinal(ix).replace(tzinfo=UTC)
ValueError: year is out of range
Updated to only show a minimum test case.
The statistics function was one that calculated the mean and standard deviation, which has been removed from the above code as it didn't impact the outcome.
