Python:TypeError: array([ 1.]) is not JSON serializable

Question

I want to convert the python plot in Html.I have taken reference example and I have changed it to convert plot to Html page.Below is my code:

import matplotlib as plta
plta.use('Agg')
import matplotlib.pyplot as plt
import numpy as np
import mpld3

fig, ax = plt.subplots(subplot_kw=dict(axisbg='#EEEEEE'))
N = 100

scatter = ax.scatter(np.random.normal(size=N),
                     np.random.normal(size=N),
                     c=np.random.random(size=N),
                     s=1000 * np.random.random(size=N),
                     alpha=0.3,
                     cmap=plt.cm.jet)

ax.grid(color='white', linestyle='solid')
ax.set_title("Scatter Plot (with tooltips!)", size=20)

labels = ['point {0}'.format(i + 1) for i in range(N)]
tooltip = mpld3.plugins.PointLabelTooltip(scatter, labels=labels)
mpld3.plugins.connect(fig, tooltip)

html_graph = mpld3.fig_to_html(fig)
with open('plot.html', 'w') as the_file:
    the_file.write(html_graph)

Now when I run above code it throws the error as below:

/usr/local/lib/python2.7/dist-packages/matplotlib/cbook/deprecation.py:106: MatplotlibDeprecationWarning: The axisbg attribute was deprecated in version 2.0. Use facecolor instead.
  warnings.warn(message, mplDeprecation, stacklevel=1)
Traceback (most recent call last):
  File "d3tool.py", line 24, in <module>
    html_graph = mpld3.fig_to_html(fig)
  File "/usr/local/lib/python2.7/dist-packages/mpld3/_display.py", line 251, in fig_to_html
    figure_json=json.dumps(figure_json, cls=NumpyEncoder),
  File "/usr/lib/python2.7/json/__init__.py", line 250, in dumps
    sort_keys=sort_keys, **kw).encode(obj)
  File "/usr/lib/python2.7/json/encoder.py", line 207, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python2.7/json/encoder.py", line 270, in iterencode
    return _iterencode(o, 0)
  File "/usr/local/lib/python2.7/dist-packages/mpld3/_display.py", line 138, in default
    return json.JSONEncoder.default(self, obj)
  File "/usr/lib/python2.7/json/encoder.py", line 184, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: array([ 1.]) is not JSON serializable

Error occurs on line 24 while calling the fig_to_html() function.Please help me.

This issue is currently open in the mpld3 repo. Here is a link: https://github.com/mpld3/mpld3/issues/434 — Abhijay Ghildyal, Dec 14 '17 at 08:52

score 6 · Accepted Answer · answered Dec 14 '17 at 08:59

I have solved my problem by changing file "mpld3/_display.py".

Please change below part:

class NumpyEncoder(json.JSONEncoder):
      """ Special json encoder for numpy types """
 -
      def default(self, obj):
          if isinstance(obj, (numpy.int_, numpy.intc, numpy.intp, numpy.int8,
              numpy.int16, numpy.int32, numpy.int64, numpy.uint8,
             numpy.uint16,numpy.uint32, numpy.uint64)):
             return int(obj)
          elif isinstance(obj, (numpy.float_, numpy.float16, numpy.float32, 
              numpy.float64)):
              return float(obj)
 +        elif isinstance(obj,(numpy.ndarray,)): #### This is the fix
 +            return obj.tolist()
          return json.JSONEncoder.default(self, obj)

Please refer https://github.com/javadba/mpld3/commit/57ed37dbc4749259b1b46cba8bf28de802972adb for more detail.

+1, +1 Thanks for taking the time to document your own solution with proper reference. It's usually quite helpful, and in this case, more helpful than the bug report. — jsfa11, May 10 '18 at 15:57

Python:TypeError: array([ 1.]) is not JSON serializable

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