Plotting Timedelta on y-axis

[scls19fr]

Code Sample

import pandas as pd
from pandas.compat import StringIO
import matplotlib.pyplot as plt


dat = """c1,c2,c3
1000,2000,1500
9000,8000,1600"""

df = pd.read_csv(StringIO(dat))

print(df)

df.plot.bar()
plt.show()

df = df.apply(lambda x: pd.to_timedelta(x, unit='ms'))

print(df)

df.plot.bar()
plt.show()

Problem description

plot.bar() works with numerical values (int, float).

     c1    c2    c3
0  1000  2000  1500
1  9000  8000  1600

not with Timedelta

        c1       c2              c3
0 00:00:01 00:00:02 00:00:01.500000
1 00:00:09 00:00:08 00:00:01.600000

    df.plot.bar()
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 2659, in bar
    return self(kind='bar', x=x, y=y, **kwds)
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 2620, in __call__
    sort_columns=sort_columns, **kwds)
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 1857, in plot_frame
    **kwds)
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 1682, in _plot
    plot_obj.generate()
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 236, in generate
    self._compute_plot_data()
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 345, in _compute_plot_data
    'plot'.format(numeric_data.__class__.__name__))
TypeError: Empty 'DataFrame': no numeric data to plot

Expected Output

Timedelta on y axis should be displayed

Output of pd.show_versions()

/Users/scls/anaconda/lib/python3.6/site-packages/xarray/core/formatting.py:16: FutureWarning: The pandas.tslib module is deprecated and will be removed in a future version. from pandas.tslib import OutOfBoundsDatetime

INSTALLED VERSIONS

commit: None
python: 3.6.1.final.0
python-bits: 64
OS: Darwin
OS-release: 16.6.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: None
LANG: fr_FR.UTF-8
LOCALE: fr_FR.UTF-8

pandas: 0.20.1
pytest: 3.1.2
pip: 9.0.1
setuptools: 27.2.0
Cython: 0.25.2
numpy: 1.12.1
scipy: 0.19.0
xarray: 0.9.5
IPython: 5.3.0
sphinx: 1.5.6
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: 3.3.0
numexpr: 2.6.2
feather: None
matplotlib: 2.0.2
openpyxl: 2.4.7
xlrd: 1.0.0
xlwt: 1.2.0
xlsxwriter: 0.9.6
lxml: 3.7.3
bs4: 4.6.0
html5lib: 0.999
sqlalchemy: 1.1.9
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: 0.4.0

[TomAugspurger]

I wonder if we could change

pandas/pandas/plotting/_core.py

Line 343 in 3955261

numeric_data = data._convert(datetime=True)._get_numeric_data()

to include timedelta=True? Maybe try changing that and seeing what breaks.

[scls19fr]

After changing

    numeric_data = data._convert(datetime=True)._get_numeric_data()

to

    numeric_data = data._convert(datetime=True, timedelta=True)._get_numeric_data()

it's still raising same exception

[imih]

The dtype of data._convert(datetime=True, timedelta=True).values is 'timedelta64[ns]' and they get filtered out by _get_numeric_data() because TimeDeltaBlock.is_numeric = False.
https://github.com/pandas-dev/pandas/blob/master/pandas/core/internals.py#L1705

numeric_data = data._convert(datetime=True, timedelta=True)
sort of works if you're fine with losing the timedelta format representation.

Got:

[scls19fr]

Plotting datetime64 on y-axis is also an issue.

import pandas as pd
from pandas.compat import StringIO
import matplotlib.pyplot as plt


dat = """c1,c2,c3
1000,2000,1500
9000,8000,1600"""

df = pd.read_csv(StringIO(dat))

print(df)
print(df.dtypes)

# df.plot.bar()
# plt.show()

df = df.apply(lambda x: pd.to_timedelta(x, unit='ms'))
for col in df.columns:
    df[col] = df[col] + pd.to_datetime('1970/01/01')

print(df)
print(df.dtypes)

df.plot.bar()
plt.show()

see

$ python mwe_pandas.py
     c1    c2    c3
0  1000  2000  1500
1  9000  8000  1600
c1    int64
c2    int64
c3    int64
dtype: object
                   c1                  c2                      c3
0 1970-01-01 00:00:01 1970-01-01 00:00:02 1970-01-01 00:00:01.500
1 1970-01-01 00:00:09 1970-01-01 00:00:08 1970-01-01 00:00:01.600
c1    datetime64[ns]
c2    datetime64[ns]
c3    datetime64[ns]
dtype: object
Traceback (most recent call last):
  File "mwe_pandas.py", line 27, in <module>
    df.plot.bar()
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 2659, in bar
    return self(kind='bar', x=x, y=y, **kwds)
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 2620, in __call__
    sort_columns=sort_columns, **kwds)
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 1857, in plot_frame
    **kwds)
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 1682, in _plot
    plot_obj.generate()
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 236, in generate
    self._compute_plot_data()
  File "/Users/scls/anaconda/lib/python3.6/site-packages/pandas/plotting/_core.py", line 345, in _compute_plot_data
    'plot'.format(numeric_data.__class__.__name__))
TypeError: Empty 'DataFrame': no numeric data to plot

[scls19fr]

Thanks @s-weigand

[scls19fr]

I tested today latest Pandas version (master)
I noticed that
#17430 fixed TypeError and now this script doesn't break but Timedelta representation on y-axis should be improved.
See #17553