How can you print a variable name in python

Question

Say I have a variable named choice it is equal to 2  How would I access the name of the variable  Something equivalent to  In  53   namestr choice  Out 53    choice    for use in making a dictionary  There s a good way to do this and I m just missing it   EDIT   The reason to do this is thus  I am running some data analysis stuff where I call the program with multiple parameters that I would like to tweak  or not tweak  at runtime  I read in the parameters I used in the last run from a  config file formated as  filename no sig resonance dat  mass peak 700  choice 1 2 3   When prompted for values  the previously used is displayed and an empty string input will use the previously used value   My question comes about because when it comes to writing the dictionary that these values have been scanned into  If a parameter is needed I run get param which accesses the file and finds the parameter    I think I will avoid the problem all together by reading the  config file once and producing a dictionary from that  I avoided that originally for    reasons I no longer remember  Perfect situation to update my code

User · Answer

You can t  as there are no variables in Python but only names   For example    gt  a    1 2 3   gt  b   a  gt  a is b True   Which of those two is now the correct variable  There s no difference between a and b   There s been a similar question before

User · Answer

Will something like this work for you    gt  gt  gt  def namestr   kwargs           for k v in kwargs items              print   s    s     k  repr v        gt  gt  gt  namestr a 1  b 2  a   1 b   2   And in your example    gt  gt  gt  choice     key   24   data   None   gt  gt  gt  namestr choice choice  choice     data   None   key   24   gt  gt  gt  printvars   globals      builtins      lt module    builtin     built-in  gt    name        main      doc     None namestr    lt function namestr at 0xb7d8ec34 gt  choice     data   None   key   24

User · Answer

Rather than ask for details to a specific solution  I recommend describing the problem you face  I think you ll get better answers   I say this since there s almost certainly a better way to do whatever it is you re trying to do   Accessing variable names in this way is not commonly needed to solve problems in any language   That said  all of your variable names are already in dictionaries which are accessible through the built-in functions locals and globals   Use the correct one for the scope you are inspecting   One of the few common idioms for inspecting these dictionaries is for easy string interpolation    gt  gt  gt  first    John   gt  gt  gt  last    Doe   gt  gt  gt  print    first s   last s    globals   John Doe   This sort of thing tends to be a bit more readable than the alternatives even though it requires inspecting variables by name

User · Answer

To answer your original question  def namestr obj  namespace       return  name for name in namespace if namespace name  is obj   Example   gt  gt  gt  a    some var   gt  gt  gt  namestr a  globals      a    As  rbright already pointed out whatever you do there are probably better ways to do it

User · Answer

If you are trying to do this  it means you are doing something wrong   Consider using a dict instead   def show val vals  name       print  Name    name   val    vals name   vals     a   1   b   2  show val vals   b     Output   Name  b val  2

User · Answer

For the revised question of how to read in configuration parameters  I d strongly recommend saving yourself some time and effort and use ConfigParser or  my preferred tool  ConfigObj   They can do everything you need  they re easy to use  and someone else has already worried about how to get them to work properly

User · Answer

With eager evaluation  variables essentially turn into their values any time you look at them  to paraphrase    That said  Python does have built-in namespaces   For example  locals   will return a dictionary mapping a function s variables  names to their values  and globals   does the same for a module   Thus   for name  value in globals   items        if value is unknown variable              do something with name   Note that you don t need to import anything to be able to access locals   and globals     Also  if there are multiple aliases for a value  iterating through a namespace only finds the first one

User · Answer

If you insist  here is some horrible inspect-based solution   import inspect  re  def varname p     for line in inspect getframeinfo inspect currentframe   f back  3       m   re search r  bvarname s    s   A-Za-z   A-Za-z0-9     s      line      if m        return m group 1   if   name         main       spam   42   print varname spam    I hope it will inspire you to reevaluate the problem you have and look for another approach

[python] How can you print a variable name in python?

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