Writing a dict to txt file and reading it back

Question

I am trying to write a dictionary to a txt file  Then read the dict values by typing the keys with raw input  I feel like I am just missing one step but I have been looking for a while now   I get this error  File  name py   line 24  in reading     print whip name  TypeError  string indices must be integers  not str   My code      usr bin env python from sys import exit  class Person object       def   init   self           self name              self address              self phone              self age              self whip           def writing self           self whip p name    p age  p address  p phone         target   open  deed txt    a           target write str self whip           print self whip      def reading self           self whip   open  deed txt    r   read           name   raw input   gt             if name in self whip              print self whip name   p   Person    while True      print  Type  n t read to read data base n t write to write to data base n t exit to exit      action   raw input   n gt         if  write  in action          p name   raw input  Name  n gt             p phone   raw input  Phone Number  n gt             p age   raw input  Age  n gt             p address   raw input  Address  n gt            p writing       elif  read  in action          p reading       elif  exit  in action          exit 0

User · Answer

Hi there is a way to write and read the dictionary to file you can turn your dictionary to JSON format and read and write quickly just do this :

To write your date:

 import json

 your_dictionary = {"some_date" : "date"}
 f = open('destFile.txt', 'w+')
 f.write(json.dumps(your_dictionary))

and to read your data:

 import json

 f = open('destFile.txt', 'r')
 your_dictionary = json.loads(f.read())

User · Answer

To store Python objects in files  use the pickle module   import pickle  a        a   1     b   2    with open  file txt    wb   as handle    pickle dump a  handle   with open  file txt    rb   as handle    b   pickle loads handle read     print a    b   True   Notice that I never set b   a  but instead pickled a to a file and then unpickled it into b   As for your error   self whip   open  deed txt    r   read     self whip was a dictionary object  deed txt contains text  so when you load the contents of deed txt into self whip  self whip becomes the string representation of itself   You d probably want to evaluate the string back into a Python object   self whip   eval open  deed txt    r   read      Notice how eval sounds like evil  That s intentional  Use the pickle module instead

User · Answer

I created my own functions which work really nicely   def writeDict dict  filename  sep       with open filename   a   as f          for i in dict keys                            f write i         sep join  str x  for x in dict i        n     It will store the keyname first  followed by all values  Note that in this case my dict contains integers so that s why it converts to int  This is most likely the part you need to change for your situation   def readDict filename  sep       with open filename   r   as f          dict              for line in f              values   line split sep              dict values 0      int x  for x in values 1 len values            return dict

User · Answer

Your code is almost right   You are right  you are just missing one step   When you read in the file  you are reading it as a string  but you want to turn the string back into a dictionary   The error message you saw was because self whip was a string  not a dictionary   I first wrote that you could just feed the string into dict   but that doesn t work   You need to do something else   Example  Here is the simplest way  feed the string into eval     Like so   def reading self       s   open  deed txt    r   read       self whip   eval s    You can do it in one line  but I think it looks messy this way   def reading self       self whip   eval open  deed txt    r   read      But eval   is sometimes not recommended   The problem is that eval   will evaluate any string  and if someone tricked you into running a really tricky string  something bad might happen   In this case  you are just running eval   on your own file  so it should be okay   But because eval   is useful  someone made an alternative to it that is safer   This is called literal eval and you get it from a Python module called ast   import ast  def reading self       s   open  deed txt    r   read       self whip   ast literal eval s    ast literal eval   will only evaluate strings that turn into the basic Python types  so there is no way that a tricky string can do something bad on your computer   EDIT  Actually  best practice in Python is to use a with statement to make sure the file gets properly closed   Rewriting the above to use a with statement   import ast  def reading self       with open  deed txt    r   as f          s   f read           self whip   ast literal eval s    In the most popular Python  known as  CPython   you usually don t need the with statement as the built-in  garbage collection  features will figure out that you are done with the file and will close it for you   But other Python implementations  like  Jython   Python for the Java VM  or  PyPy   a really cool experimental system with just-in-time code optimization  might not figure out to close the file for you   It s good to get in the habit of using with  and I think it makes the code pretty easy to understand

User · Answer

You can iterate through the key-value pair and write it into file  pair     name   name  location   location  with open  F   twitter json    a   as f       f writelines         format k v  for k  v in pair items         f write   n

User · Answer

Have you tried the json module  JSON format is very similar to python dictionary  And it s human readable writable    gt  gt  gt  import json  gt  gt  gt  d     one  1   two  2   gt  gt  gt  json dump d  open  text txt   w      This code dumps to a text file    cat text txt    two   2   one   1    Also you can load from a JSON file    gt  gt  gt  d2   json load open  text txt     gt  gt  gt  print d2  u two   2  u one   1

[python] Writing a dict to txt file and reading it back?

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