3.3.0: possible regression/bug with DateFormatter?

Hello,
i have this code that worked fine until mpl 3.3.0; now if you run it, it generate this image - notice the X axes tick labels, 3989? that's supposed to be 2020 :) (for comparison you can look at last month image )

Is there anything wrong with that code i was using or is there a bug/regression in mpl?

thanks!

https://matplotlib.org/3.3.0/users/whats_new.html#dates-use-a-modern-epoch

But I don't understand why your dates, which seem to be just datetime objects, are not just working.

I cannot reproduce this on master or v.3.3.0.

I get:

Even if I change plt.rcParams['date.epoch'] = '1970-01-01T00:00:00' or plt.rcParams['date.epoch'] = '0000-12-31T00:00:00' I get the same image. So this is a bit of a mystery as to why its not working for you.

If you do

import matplotlib.dates as mdates
import datetime

print(mdates.get_epoch())
print(mdates.date2num(datetime.datetime(2020, 1, 1)))

and report the results, that would be useful. For me I get

1970-01-01T00:00:00
18262.0

yep, same:

In [62]: import matplotlib.dates as mdates 
    ...: import datetime 
    ...:  
    ...: print(mdates.get_epoch()) 
    ...: print(mdates.date2num(datetime.datetime(2020, 1, 1)))                                                                                                                                                                                                                  
1970-01-01T00:00:00
18262.0

In [63]: matplotlib.__version__                                                                                                                                                                                                                                                 
Out[63]: '3.3.0'

could be some outdated rcparams?

In [64]: matplotlib.rcParams                                                                                                                                                                                                                                                    
Out[64]: 
RcParams({'_internal.classic_mode': False,
          'agg.path.chunksize': 0,
          'animation.avconv_args': [],
          'animation.avconv_path': 'avconv',
          'animation.bitrate': -1,
          'animation.codec': 'h264',
          'animation.convert_args': [],
          'animation.convert_path': 'convert',
          'animation.embed_limit': 20.0,
          'animation.ffmpeg_args': [],
          'animation.ffmpeg_path': 'ffmpeg',
          'animation.frame_format': 'png',
          'animation.html': 'none',
          'animation.html_args': [],
          'animation.writer': 'ffmpeg',
          'axes.autolimit_mode': 'data',
          'axes.axisbelow': 'line',
          'axes.edgecolor': 'black',
          'axes.facecolor': 'white',
          'axes.formatter.limits': [-5, 6],
          'axes.formatter.min_exponent': 0,
          'axes.formatter.offset_threshold': 4,
          'axes.formatter.use_locale': False,
          'axes.formatter.use_mathtext': False,
          'axes.formatter.useoffset': True,
          'axes.grid': False,
          'axes.grid.axis': 'both',
          'axes.grid.which': 'major',
          'axes.labelcolor': 'black',
          'axes.labelpad': 4.0,
          'axes.labelsize': 'medium',
          'axes.labelweight': 'normal',
          'axes.linewidth': 0.8,
          'axes.prop_cycle': cycler('color', ['#1f77b4', '#ff7f0e', '#2ca02c', '#d62728', '#9467bd', '#8c564b', '#e377c2', '#7f7f7f', '#bcbd22', '#17becf']),
          'axes.spines.bottom': True,
          'axes.spines.left': True,
          'axes.spines.right': True,
          'axes.spines.top': True,
          'axes.titlecolor': 'auto',
          'axes.titlelocation': 'center',
          'axes.titlepad': 6.0,
          'axes.titlesize': 'large',
          'axes.titleweight': 'normal',
          'axes.titley': None,
          'axes.unicode_minus': True,
          'axes.xmargin': 0.05,
          'axes.ymargin': 0.05,
          'axes3d.grid': True,
          'backend': 'TkAgg',
          'backend_fallback': True,
          'boxplot.bootstrap': None,
          'boxplot.boxprops.color': 'black',
          'boxplot.boxprops.linestyle': '-',
          'boxplot.boxprops.linewidth': 1.0,
          'boxplot.capprops.color': 'black',
          'boxplot.capprops.linestyle': '-',
          'boxplot.capprops.linewidth': 1.0,
          'boxplot.flierprops.color': 'black',
          'boxplot.flierprops.linestyle': 'none',
          'boxplot.flierprops.linewidth': 1.0,
          'boxplot.flierprops.marker': 'o',
          'boxplot.flierprops.markeredgecolor': 'black',
          'boxplot.flierprops.markeredgewidth': 1.0,
          'boxplot.flierprops.markerfacecolor': 'none',
          'boxplot.flierprops.markersize': 6.0,
          'boxplot.meanline': False,
          'boxplot.meanprops.color': 'C2',
          'boxplot.meanprops.linestyle': '--',
          'boxplot.meanprops.linewidth': 1.0,
          'boxplot.meanprops.marker': '^',
          'boxplot.meanprops.markeredgecolor': 'C2',
          'boxplot.meanprops.markerfacecolor': 'C2',
          'boxplot.meanprops.markersize': 6.0,
          'boxplot.medianprops.color': 'C1',
          'boxplot.medianprops.linestyle': '-',
          'boxplot.medianprops.linewidth': 1.0,
          'boxplot.notch': False,
          'boxplot.patchartist': False,
          'boxplot.showbox': True,
          'boxplot.showcaps': True,
          'boxplot.showfliers': True,
          'boxplot.showmeans': False,
          'boxplot.vertical': True,
          'boxplot.whiskerprops.color': 'black',
          'boxplot.whiskerprops.linestyle': '-',
          'boxplot.whiskerprops.linewidth': 1.0,
          'boxplot.whiskers': 1.5,
          'contour.corner_mask': True,
          'contour.linewidth': None,
          'contour.negative_linestyle': 'dashed',
          'date.autoformatter.day': '%Y-%m-%d',
          'date.autoformatter.hour': '%m-%d %H',
          'date.autoformatter.microsecond': '%M:%S.%f',
          'date.autoformatter.minute': '%d %H:%M',
          'date.autoformatter.month': '%Y-%m',
          'date.autoformatter.second': '%H:%M:%S',
          'date.autoformatter.year': '%Y',
          'date.epoch': '1970-01-01T00:00:00',
          'docstring.hardcopy': False,
          'errorbar.capsize': 0.0,
          'figure.autolayout': False,
          'figure.constrained_layout.h_pad': 0.04167,
          'figure.constrained_layout.hspace': 0.02,
          'figure.constrained_layout.use': False,
          'figure.constrained_layout.w_pad': 0.04167,
          'figure.constrained_layout.wspace': 0.02,
          'figure.dpi': 100.0,
          'figure.edgecolor': 'white',
          'figure.facecolor': 'white',
          'figure.figsize': [6.4, 4.8],
          'figure.frameon': True,
          'figure.max_open_warning': 20,
          'figure.raise_window': True,
          'figure.subplot.bottom': 0.11,
          'figure.subplot.hspace': 0.2,
          'figure.subplot.left': 0.125,
          'figure.subplot.right': 0.9,
          'figure.subplot.top': 0.88,
          'figure.subplot.wspace': 0.2,
          'figure.titlesize': 'large',
          'figure.titleweight': 'normal',
          'font.cursive': ['Apple Chancery',
                           'Textile',
                           'Zapf Chancery',
                           'Sand',
                           'Script MT',
                           'Felipa',
                           'cursive'],
          'font.family': ['sans-serif'],
          'font.fantasy': ['Comic Neue',
                           'Comic Sans MS',
                           'Chicago',
                           'Charcoal',
                           'ImpactWestern',
                           'Humor Sans',
                           'xkcd',
                           'fantasy'],
          'font.monospace': ['DejaVu Sans Mono',
                             'Bitstream Vera Sans Mono',
                             'Computer Modern Typewriter',
                             'Andale Mono',
                             'Nimbus Mono L',
                             'Courier New',
                             'Courier',
                             'Fixed',
                             'Terminal',
                             'monospace'],
          'font.sans-serif': ['DejaVu Sans',
                              'Bitstream Vera Sans',
                              'Computer Modern Sans Serif',
                              'Lucida Grande',
                              'Verdana',
                              'Geneva',
                              'Lucid',
                              'Arial',
                              'Helvetica',
                              'Avant Garde',
                              'sans-serif'],
          'font.serif': ['DejaVu Serif',
                         'Bitstream Vera Serif',
                         'Computer Modern Roman',
                         'New Century Schoolbook',
                         'Century Schoolbook L',
                         'Utopia',
                         'ITC Bookman',
                         'Bookman',
                         'Nimbus Roman No9 L',
                         'Times New Roman',
                         'Times',
                         'Palatino',
                         'Charter',
                         'serif'],
          'font.size': 10.0,
          'font.stretch': 'normal',
          'font.style': 'normal',
          'font.variant': 'normal',
          'font.weight': 'normal',
          'grid.alpha': 1.0,
          'grid.color': '#b0b0b0',
          'grid.linestyle': '-',
          'grid.linewidth': 0.8,
          'hatch.color': 'black',
          'hatch.linewidth': 1.0,
          'hist.bins': 10,
          'image.aspect': 'equal',
          'image.cmap': 'viridis',
          'image.composite_image': True,
          'image.interpolation': 'antialiased',
          'image.lut': 256,
          'image.origin': 'upper',
          'image.resample': True,
          'interactive': False,
          'keymap.all_axes': ['a'],
          'keymap.back': ['left', 'c', 'backspace', 'MouseButton.BACK'],
          'keymap.copy': ['ctrl+c', 'cmd+c'],
          'keymap.forward': ['right', 'v', 'MouseButton.FORWARD'],
          'keymap.fullscreen': ['f', 'ctrl+f'],
          'keymap.grid': ['g'],
          'keymap.grid_minor': ['G'],
          'keymap.help': ['f1'],
          'keymap.home': ['h', 'r', 'home'],
          'keymap.pan': ['p'],
          'keymap.quit': ['ctrl+w', 'cmd+w', 'q'],
          'keymap.quit_all': [],
          'keymap.save': ['s', 'ctrl+s'],
          'keymap.xscale': ['k', 'L'],
          'keymap.yscale': ['l'],
          'keymap.zoom': ['o'],
          'legend.borderaxespad': 0.5,
          'legend.borderpad': 0.4,
          'legend.columnspacing': 2.0,
          'legend.edgecolor': '0.8',
          'legend.facecolor': 'inherit',
          'legend.fancybox': True,
          'legend.fontsize': 'medium',
          'legend.framealpha': 0.8,
          'legend.frameon': True,
          'legend.handleheight': 0.7,
          'legend.handlelength': 2.0,
          'legend.handletextpad': 0.8,
          'legend.labelspacing': 0.5,
          'legend.loc': 'best',
          'legend.markerscale': 1.0,
          'legend.numpoints': 1,
          'legend.scatterpoints': 1,
          'legend.shadow': False,
          'legend.title_fontsize': None,
          'lines.antialiased': True,
          'lines.color': 'C0',
          'lines.dash_capstyle': 'butt',
          'lines.dash_joinstyle': 'round',
          'lines.dashdot_pattern': [6.4, 1.6, 1.0, 1.6],
          'lines.dashed_pattern': [3.7, 1.6],
          'lines.dotted_pattern': [1.0, 1.65],
          'lines.linestyle': '-',
          'lines.linewidth': 1.5,
          'lines.marker': 'None',
          'lines.markeredgecolor': 'auto',
          'lines.markeredgewidth': 1.0,
          'lines.markerfacecolor': 'auto',
          'lines.markersize': 6.0,
          'lines.scale_dashes': True,
          'lines.solid_capstyle': 'projecting',
          'lines.solid_joinstyle': 'round',
          'markers.fillstyle': 'full',
          'mathtext.bf': 'sans:bold',
          'mathtext.cal': 'cursive',
          'mathtext.default': 'it',
          'mathtext.fallback': 'cm',
          'mathtext.fallback_to_cm': None,
          'mathtext.fontset': 'dejavusans',
          'mathtext.it': 'sans:italic',
          'mathtext.rm': 'sans',
          'mathtext.sf': 'sans',
          'mathtext.tt': 'monospace',
          'mpl_toolkits.legacy_colorbar': True,
          'patch.antialiased': True,
          'patch.edgecolor': 'black',
          'patch.facecolor': 'C0',
          'patch.force_edgecolor': False,
          'patch.linewidth': 1.0,
          'path.effects': [],
          'path.simplify': True,
          'path.simplify_threshold': 0.111111111111,
          'path.sketch': None,
          'path.snap': True,
          'pcolor.shading': 'flat',
          'pdf.compression': 6,
          'pdf.fonttype': 3,
          'pdf.inheritcolor': False,
          'pdf.use14corefonts': False,
          'pgf.preamble': '',
          'pgf.rcfonts': True,
          'pgf.texsystem': 'xelatex',
          'polaraxes.grid': True,
          'ps.distiller.res': 6000,
          'ps.fonttype': 3,
          'ps.papersize': 'letter',
          'ps.useafm': False,
          'ps.usedistiller': None,
          'savefig.bbox': None,
          'savefig.directory': '~',
          'savefig.dpi': 'figure',
          'savefig.edgecolor': 'auto',
          'savefig.facecolor': 'auto',
          'savefig.format': 'png',
          'savefig.jpeg_quality': 95,
          'savefig.orientation': 'portrait',
          'savefig.pad_inches': 0.1,
          'savefig.transparent': False,
          'scatter.edgecolors': 'face',
          'scatter.marker': 'o',
          'svg.fonttype': 'path',
          'svg.hashsalt': None,
          'svg.image_inline': True,
          'text.antialiased': True,
          'text.color': 'black',
          'text.hinting': 'force_autohint',
          'text.hinting_factor': 8,
          'text.kerning_factor': 0,
          'text.latex.preamble': '',
          'text.latex.preview': False,
          'text.usetex': False,
          'timezone': 'UTC',
          'tk.window_focus': False,
          'toolbar': 'toolbar2',
          'webagg.address': '127.0.0.1',
          'webagg.open_in_browser': True,
          'webagg.port': 8988,
          'webagg.port_retries': 50,
          'xaxis.labellocation': 'center',
          'xtick.alignment': 'center',
          'xtick.bottom': True,
          'xtick.color': 'black',
          'xtick.direction': 'out',
          'xtick.labelbottom': True,
          'xtick.labelsize': 'medium',
          'xtick.labeltop': False,
          'xtick.major.bottom': True,
          'xtick.major.pad': 3.5,
          'xtick.major.size': 3.5,
          'xtick.major.top': True,
          'xtick.major.width': 0.8,
          'xtick.minor.bottom': True,
          'xtick.minor.pad': 3.4,
          'xtick.minor.size': 2.0,
          'xtick.minor.top': True,
          'xtick.minor.visible': False,
          'xtick.minor.width': 0.6,
          'xtick.top': False,
          'yaxis.labellocation': 'center',
          'ytick.alignment': 'center_baseline',
          'ytick.color': 'black',
          'ytick.direction': 'out',
          'ytick.labelleft': True,
          'ytick.labelright': False,
          'ytick.labelsize': 'medium',
          'ytick.left': True,
          'ytick.major.left': True,
          'ytick.major.pad': 3.5,
          'ytick.major.right': True,
          'ytick.major.size': 3.5,
          'ytick.major.width': 0.8,
          'ytick.minor.left': True,
          'ytick.minor.pad': 3.4,
          'ytick.minor.right': True,
          'ytick.minor.size': 2.0,
          'ytick.minor.visible': False,
          'ytick.minor.width': 0.6,
          'ytick.right': False})

The relevant new rcParam is date.epoch and its correct.

Is it something funny in your env? What happens if you simplify this to:

import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import datetime
import numpy as np

print(mdates.get_epoch())
print(mdates.date2num(datetime.datetime(2020, 1, 1)))

dates = {datetime.datetime(2016, 2, 1, 0, 0): datetime.datetime(2015, 10, 1, 0, 0), datetime.datetime(2020, 6, 1, 0, 0): datetime.datetime(2017, 11, 8, 0, 0), datetime.datetime(2017, 8, 1, 0, 0): datetime.datetime(2017, 8, 1, 0, 0), datetime.datetime(2018, 4, 1, 0, 0): datetime.datetime(2018, 4, 1, 0, 0), datetime.datetime(2020, 8, 1, 0, 0): datetime.datetime(2019, 4, 1, 0, 0), datetime.datetime(2019, 11, 1, 0, 0): datetime.datetime(2019, 11, 1, 0, 0), datetime.datetime(2019, 9, 1, 0, 0): datetime.datetime(2016, 7, 1, 0, 0), datetime.datetime(2019, 5, 1, 0, 0): datetime.datetime(2019, 5, 1, 0, 0), datetime.datetime(2018, 6, 1, 0, 0): datetime.datetime(2018, 6, 1, 0, 0), datetime.datetime(2020, 1, 1, 0, 0): datetime.datetime(2020, 1, 1, 0, 0), datetime.datetime(2018, 2, 1, 0, 0): datetime.datetime(2018, 2, 1, 0, 0), datetime.datetime(2017, 7, 1, 0, 0): datetime.datetime(2017, 6, 8, 0, 0), datetime.datetime(2017, 12, 1, 0, 0): datetime.datetime(2017, 12, 1, 0, 0), datetime.datetime(2017, 9, 1, 0, 0): datetime.datetime(2017, 9, 1, 0, 0), datetime.datetime(2019, 1, 1, 0, 0): datetime.datetime(2019, 1, 1, 0, 0), datetime.datetime(2019, 3, 1, 0, 0): datetime.datetime(2019, 3, 1, 0, 0), datetime.datetime(2016, 9, 1, 0, 0): datetime.datetime(2016, 5, 1, 0, 0), datetime.datetime(2018, 10, 1, 0, 0): datetime.datetime(2018, 10, 1, 0, 0), datetime.datetime(2016, 12, 1, 0, 0): datetime.datetime(2016, 7, 1, 0, 0), datetime.datetime(2016, 4, 1, 0, 0): datetime.datetime(2016, 2, 15, 0, 0), datetime.datetime(2018, 8, 1, 0, 0): datetime.datetime(2018, 8, 1, 0, 0), datetime.datetime(2015, 11, 1, 0, 0): datetime.datetime(2015, 8, 15, 0, 0), datetime.datetime(2019, 7, 1, 0, 0): datetime.datetime(2019, 7, 1, 0, 0), datetime.datetime(2018, 5, 1, 0, 0): datetime.datetime(2018, 5, 1, 0, 0), datetime.datetime(2017, 10, 1, 0, 0): datetime.datetime(2017, 10, 1, 0, 0), datetime.datetime(2015, 12, 1, 0, 0): datetime.datetime(2015, 9, 1, 0, 0), datetime.datetime(2020, 2, 1, 0, 0): datetime.datetime(2020, 2, 1, 0, 0), datetime.datetime(2016, 7, 1, 0, 0): datetime.datetime(2016, 3, 1, 0, 0), datetime.datetime(2016, 3, 1, 0, 0): datetime.datetime(2016, 1, 1, 0, 0), datetime.datetime(2019, 10, 1, 0, 0): datetime.datetime(2019, 10, 1, 0, 0), datetime.datetime(2020, 5, 1, 0, 0): datetime.datetime(2017, 1, 1, 0, 0), datetime.datetime(2019, 2, 1, 0, 0): datetime.datetime(2019, 2, 1, 0, 0), datetime.datetime(2019, 4, 1, 0, 0): datetime.datetime(2019, 4, 1, 0, 0), datetime.datetime(2018, 11, 1, 0, 0): datetime.datetime(2018, 11, 1, 0, 0), datetime.datetime(2017, 5, 1, 0, 0): datetime.datetime(2017, 3, 15, 0, 0), datetime.datetime(2019, 6, 1, 0, 0): datetime.datetime(2019, 6, 1, 0, 0), datetime.datetime(2017, 1, 1, 0, 0): datetime.datetime(2016, 8, 1, 0, 0), datetime.datetime(2018, 3, 1, 0, 0): datetime.datetime(2018, 3, 1, 0, 0), datetime.datetime(2020, 4, 1, 0, 0): datetime.datetime(2017, 1, 1, 0, 0), datetime.datetime(2018, 1, 1, 0, 0): datetime.datetime(2018, 1, 1, 0, 0), datetime.datetime(2017, 11, 1, 0, 0): datetime.datetime(2017, 11, 1, 0, 0), datetime.datetime(2020, 3, 1, 0, 0): datetime.datetime(2017, 1, 1, 0, 0), datetime.datetime(2017, 2, 1, 0, 0): datetime.datetime(2016, 10, 1, 0, 0), datetime.datetime(2016, 6, 1, 0, 0): datetime.datetime(2016, 2, 15, 0, 0), datetime.datetime(2016, 10, 1, 0, 0): datetime.datetime(2016, 6, 1, 0, 0), datetime.datetime(2020, 7, 1, 0, 0): datetime.datetime(2018, 4, 15, 0, 0), datetime.datetime(2017, 6, 1, 0, 0): datetime.datetime(2017, 4, 15, 0, 0), datetime.datetime(2018, 12, 1, 0, 0): datetime.datetime(2018, 12, 1, 0, 0), datetime.datetime(2018, 7, 1, 0, 0): datetime.datetime(2018, 7, 1, 0, 0), datetime.datetime(2016, 11, 1, 0, 0): datetime.datetime(2016, 7, 1, 0, 0), datetime.datetime(2016, 1, 1, 0, 0): datetime.datetime(2015, 10, 1, 0, 0), datetime.datetime(2016, 8, 1, 0, 0): datetime.datetime(2016, 3, 15, 0, 0), datetime.datetime(2019, 12, 1, 0, 0): datetime.datetime(2019, 12, 1, 0, 0), datetime.datetime(2016, 5, 1, 0, 0): datetime.datetime(2016, 2, 15, 0, 0), datetime.datetime(2015, 10, 1, 0, 0): datetime.datetime(2015, 8, 15, 0, 0), datetime.datetime(2017, 4, 1, 0, 0): datetime.datetime(2017, 2, 15, 0, 0), datetime.datetime(2017, 3, 1, 0, 0): datetime.datetime(2016, 12, 1, 0, 0), datetime.datetime(2019, 8, 1, 0, 0): datetime.datetime(2016, 7, 1, 0, 0), datetime.datetime(2018, 9, 1, 0, 0): datetime.datetime(2016, 11, 1, 0, 0)}

plt.plot(sorted(dates.keys()), np.arange(len(dates)))
plt.show()

from your ipython shell does it still give the strange dates? EDIT: they're not strange, they are just 1970 years too far in the future. ie the datenum is coming out as one that has the old epoch, but then getting converted back using the new one.

Also can't hurt to make sure this roundtrips:

print(mdates.num2date(18262.0))

i tried your code and i get the weird dates

In [66]: print(mdates.num2date(18262.0))                                                                                                                                                                                                                                        
2020-01-01 00:00:00+00:00

(if you prefer a different way to debug this, like maybe on discord or smth, just let me know :) )

loc = mdates.AutoDateLocator()
formatter = mdates.AutoDateFormatter(loc)
print(formatter(18262.0))

Gives me 2020...

BTW, not sure if discord would help, and this is fine for tracking the issue. OTOH, I'm not sure what else I can do. It'd be good if you could reproduce on a fresh env. If I do conda create -n boo matplotlib numpy and conda activate boo I get the same results. So I'm pretty mystified.

weirder and weirder: if i restart ipython, i get the right dates too! but i run the original script from the command-line, still 3989 ....

That is strange - seems like a crossed-up install, but not sure I understand why. I guess you could put the print statements above into a script and run from the command line.

$ cat ~/tmp/issue18010_1.py
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import datetime
import numpy as np

loc = mdates.AutoDateLocator()
formatter = mdates.AutoDateFormatter(loc)
print(formatter(18262.0))

print(mdates.num2date(18262.0))

$ python3 ~/tmp/issue18010_1.py
2020
2020-01-01 00:00:00+00:00

ok, it looks like i may have had to pay more attention to the message on the console:

/usr/lib/python3/dist-packages/pandas/plotting/_matplotlib/converter.py:103: FutureWarning: Using an implicitly registered datetime converter for a matplotlib plotting method. The converter was registered by pandas on import. Future versions of pandas will require you to explicitly register matplotlib converters.

To register the converters:
        >>> from pandas.plotting import register_matplotlib_converters
        >>> register_matplotlib_converters()
  warnings.warn(msg, FutureWarning)
/usr/lib/python3/dist-packages/pandas/plotting/_matplotlib/converter.py:245: MatplotlibDeprecationWarning: 
The epoch2num function was deprecated in Matplotlib 3.3 and will be removed two minor releases later.
  base = dates.epoch2num(dt.asi8 / 1.0e9)

that's produced when executing the script on console: is this our smoking gun?

Yes; Epoch2num was not updated to the new epoch. So this will be closed by a PR from yesterday. But I still don't 100% understand because you are explicitly using matplotlib's formatter.

@sandrotosi

@sandrotosi so was one of your pandas pre 1.0.0?

I think all this speaks to getting #17983 in a release as soon as possible to address this conflict, at least for folks using older pandas. See also pandas-dev/pandas#35350, pandas-dev/pandas#34850, and pandas-dev/pandas#35361

@sandrotosi

@sandrotosi so was one of your pandas pre 1.0.0?

yes, on my system i have pandas/0.25.3 while there is no pandas installed in the container

I think all this speaks to getting #17983 in a release as soon as possible to address this conflict, at least for folks using older pandas. See also pandas-dev/pandas#35350, pandas-dev/pandas#34850, and pandas-dev/pandas#35361

lemme apply that patch (hoping it applies cleanly on top of 3.3.0) to the debian package and re-try; will update as soon as the build process finishes so... not very soon :)

yep that was it: with that PR applied on top of 3.3.0, the script now works fine. i'm gonna upload the fix to Debian, but I agree a .1 with that patch released officially would be ideal -- thanks for debugging this with me!

Can someone unpack this thread? What is the final outcome as it stands?

tldr; for those landing here. Using matplotlib master fixes this.

might want to check this https://stackoverflow.com/questions/63078267/x-axis-in-matplotlib-print-random-numbers-instead-of-the-years/63079594#63079594

Closing, as this will be fixed in 3.3.1.

Just for posterity sake, the workaround is to manually specify the old pre-3.3.0 epoch in your script.

plt.rcParams['date.epoch'] = '0000-12-31T00:00'

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3.3.0: possible regression/bug with DateFormatter? #18010

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3.3.0: possible regression/bug with DateFormatter? #18010

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jklymak commented on Jul 22, 2020

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sandrotosi commented on Jul 22, 2020

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jklymak commented on Jul 24, 2020

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