How can I use pickle to save a dict

Question

I have looked through the information that the Python docs give  but I m still a little confused  Could somebody post sample code that would write a new file then use pickle to dump a dictionary into it

User · Accepted Answer

Try this   import pickle  a     hello    world    with open  filename pickle    wb   as handle      pickle dump a  handle  protocol pickle HIGHEST PROTOCOL   with open  filename pickle    rb   as handle      b   pickle load handle   print a    b

User · Answer

import pickle  dictobj     Jack    123   John    456   filename     foldername filestore   fileobj   open filename   wb    pickle dump dictobj  fileobj   fileobj close

User · Answer

Simple way to dump a Python data  e g  dictionary  to a pickle file   import pickle  your dictionary       pickle dump your dictionary  open  pickle file name p    wb

User · Answer

I ve found pickling confusing  possibly because I m thick    I found that this works  though   myDictionaryString str myDictionary    Which you can then write to a text file   I gave up trying to use pickle as I was getting errors telling me to write integers to a  dat file   I apologise for not using pickle

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gt  gt  gt  import pickle  gt  gt  gt  with open   tmp picklefile    wb   as f          pickle dump     f         normally it s preferable to use the cPickle implementation   gt  gt  gt  import cPickle as pickle  gt  gt  gt  help pickle dump  Help on built-in function dump in module cPickle   dump          dump obj  file  protocol 0  -- Write an object in pickle format to the given file       See the Pickler docstring for the meaning of optional argument proto

User · Answer

If you just want to store the dict in a single file  use pickle like that  import pickle  a     hello    world    with open  filename pickle    wb   as handle      pickle dump a  handle   with open  filename pickle    rb   as handle      b   pickle load handle    If you want to save and restore multiple dictionaries in multiple files for  caching and store more complex data   use anycache   It does all the other stuff you need around pickle  from anycache import anycache   anycache cachedir  path to files   def myfunc hello       return   hello   hello    Anycache stores the different myfunc results depending on the arguments to  different files in cachedir and reloads them   See the documentation for any further details

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Save a dictionary into a pickle file  import pickle  favorite color     lion    yellow    kitty    red      create a dictionary pickle dump favorite color  open  save p    wb       save it into a file named save p    -------------------------------------------------------------   Load the dictionary back from the pickle file  import pickle  favorite color   pickle load open  save p    rb      favorite color is now   lion    yellow    kitty    red

User · Answer

In general  pickling a dict will fail unless you have only simple objects in it  like strings and integers   Python 2 7 9  default  Dec 11 2014  01 21 43    GCC 4 2 1 Compatible Apple Clang 4 1   tags Apple clang-421 11 66    on darwin Type  help    copyright    credits  or  license  for more information   gt  gt  gt  from numpy import    gt  gt  gt  type globals          lt type  dict  gt   gt  gt  gt  import pickle  gt  gt  gt  pik   pickle dumps globals    Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 1374  in dumps     Pickler file  protocol  dump obj    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 224  in dump     self save obj    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 286  in save     f self  obj    Call unbound method with explicit self   File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 649  in save dict     self  batch setitems obj iteritems      File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 663  in  batch setitems     save v    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 306  in save     rv   reduce self proto    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 copy reg py   line 70  in  reduce ex     raise TypeError   can t pickle  s objects    base   name   TypeError  can t pickle module objects  gt  gt  gt     Even a really simple dict will often fail   It just depends on the contents    gt  gt  gt  d     x   lambda x x   gt  gt  gt  pik   pickle dumps d  Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 1374  in dumps     Pickler file  protocol  dump obj    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 224  in dump     self save obj    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 286  in save     f self  obj    Call unbound method with explicit self   File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 649  in save dict     self  batch setitems obj iteritems      File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 663  in  batch setitems     save v    File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 286  in save     f self  obj    Call unbound method with explicit self   File   opt local Library Frameworks Python framework Versions 2 7 lib python2 7 pickle py   line 748  in save global      obj  module  name   pickle PicklingError  Can t pickle  lt function  lt lambda gt  at 0x102178668 gt   it s not found as   main    lt lambda gt    However  if you use a better serializer like dill or cloudpickle  then most dictionaries can be pickled    gt  gt  gt  import dill  gt  gt  gt  pik   dill dumps d    Or if you want to save your dict to a file      gt  gt  gt  with open  save pik    w   as f        dill dump globals    f         The latter example is identical to any of the other good answers posted here  which aside from neglecting the picklability of the contents of the dict are good

User · Answer

import pickle  your data     foo    bar      Store data  serialize  with open  filename pickle    wb   as handle      pickle dump your data  handle  protocol pickle HIGHEST PROTOCOL     Load data  deserialize  with open  filename pickle    rb   as handle      unserialized data   pickle load handle   print your data    unserialized data    The advantage of HIGHEST PROTOCOL is that files get smaller  This makes unpickling sometimes much faster   Important notice  The maximum file size of pickle is about 2GB   Alternative way  import mpu your data     foo    bar   mpu io write  filename pickle   data  unserialized data   mpu io read  filename pickle     Alternative Formats   CSV  Super simple format  read  amp  write  JSON  Nice for writing human-readable data  VERY commonly used  read  amp  write  YAML  YAML is a superset of JSON  but easier to read  read  amp  write  comparison of JSON and YAML  pickle  A Python serialization format  read  amp  write  MessagePack  Python package   More compact representation  read  amp  write  HDF5  Python package   Nice for matrices  read  amp  write  XML  exists too  sigh   read  amp  write    For your application  the following might be important    Support by other programming languages Reading   writing performance Compactness  file size    See also  Comparison of data serialization formats  In case you are rather looking for a way to make configuration files  you might want to read my short article Configuration files in Python

[python] How can I use pickle to save a dict?

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