Python Forum

Hi,

I am new to Python and Jupyter Notebook and I get the error below in Jupyter Notebook while the code works in Spyder:

import base64
import json
import subprocess

def output_image(name, format, bytes):
    image_start = "BEGIN_IMAGE_f9825uweof8jw9fj4r8"
    image_end = "END_IMAGE_0238jfw08fjsiufhw8frs"
    data = {}
    data['name'] = name
    data['format'] = format
    data['bytes'] = base64.encodestring(bytes)
    print(image_start + json.dumps(data) + image_end)

Error:
TypeError                                 Traceback (most recent call last)
<ipython-input-16-f9e8ef7a162f> in <module>()
      1 ### draw the decision boundary with the text points overlaid
      2 instanceCV.prettyPicture(clf, features_test, labels_test)
----> 3 instanceCV.output_image("test.png", "png", open("test.png", "rb").read())

<ipython-input-10-99476019b17b> in output_image(self, name, format, bytes)
     71         data['format'] = format
     72         data['bytes'] = base64.encodestring(bytes)
---> 73         print(image_start + json.dumps(data) + image_end)

C:\ProgramData\Anaconda3\lib\json\__init__.py in dumps(obj, skipkeys, ensure_ascii, check_circular, allow_nan, cls, indent, separators, default, sort_keys, **kw)
    229         cls is None and indent is None and separators is None and
    230         default is None and not sort_keys and not kw):
--> 231         return _default_encoder.encode(obj)
    232     if cls is None:
    233         cls = JSONEncoder

C:\ProgramData\Anaconda3\lib\json\encoder.py in encode(self, o)
    197         # exceptions aren't as detailed.  The list call should be roughly
    198         # equivalent to the PySequence_Fast that ''.join() would do.
--> 199         chunks = self.iterencode(o, _one_shot=True)
    200         if not isinstance(chunks, (list, tuple)):
    201             chunks = list(chunks)

C:\ProgramData\Anaconda3\lib\json\encoder.py in iterencode(self, o, _one_shot)
    255                 self.key_separator, self.item_separator, self.sort_keys,
    256                 self.skipkeys, _one_shot)
--> 257         return _iterencode(o, 0)
    258 
    259 def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,

Thanks for help

(Jun-17-2018, 09:37 AM)diet Wrote: [ -> ]Hi,

I am new to Python and Jupyter Notebook and I get the error below in Jupyter Notebook while the code works in Spyder:

import base64
import json
import subprocess

def output_image(name, format, bytes):
    image_start = "BEGIN_IMAGE_f9825uweof8jw9fj4r8"
    image_end = "END_IMAGE_0238jfw08fjsiufhw8frs"
    data = {}
    data['name'] = name
    data['format'] = format
    data['bytes'] = base64.encodestring(bytes)
    print(image_start + json.dumps(data) + image_end)

One thing that is dangerous in your code - you override (shadow) global name format. Maybe that is not your issue - but it is a potentially dangerous substitution

The problem is that you have bytes b'something' in dictionary data.
JSON format only supports Unicode strings.
As mention bye @volcano63 you overwrite format,but also bytes is a used name bye Python.

>>> format
<built-in function format>
>>> bytes
<class 'bytes'>

>>> # A name that not used give NameError
>>> foo
Traceback (most recent call last):
  File "<string>", line 428, in runcode
  File "<interactive input>", line 1, in <module>
NameError: name 'foo' is not defined 

You should also show what you call function with,now do i see that in error message that it's png image.
Since Base64 encodes bytes to ASCII-only bytes,you can use that codec to decode the data so it can be dumped to JSON.

import base64
import json
import subprocess
 
def output_image(name, file_format, img_bytes):
    image_start = "BEGIN_IMAGE_f9825uweof8jw9fj4r8"
    image_end = "END_IMAGE_0238jfw08fjsiufhw8frs"
    data = {}
    data['name'] = name
    data['format'] = file_format
    encoded = data['bytes'] = base64.encodestring(img_bytes)
    # Fix
    data['bytes'] = encoded.decode('ascii')     
    print(image_start + json.dumps(data) + image_end)
    
output_image('logo.png', 'png', open("logo.png", "rb").read())

The question remains about working in Spyder and not working in Jupyter. I have a nagging suspicion that Jupyter is running Python3, and Spyder - Python2.

(Jun-17-2018, 03:13 PM)volcano63 Wrote: [ -> ]I have a nagging suspicion that Jupyter is running Python3, and Spyder - Python2

Yes i think that to.
@diet check from where you run Spyder,for Python 3 Spyder should be run from your Anaconda3\Scripts folder or from Navigator Anaconda3.

Do you have a newer download of Anaconda3 Spyder may not be there bye default(may need install),
as you see in VS Code Bundled with Anaconda so have they switch to VS Code and do not support Spyder anymore.