Appending values to dictionary in Python

Question

I have a dictionary to which I want to append to each drug  a list of numbers  Like this   append 0   append 1234   append 123   etc   def make drug dictionary data       drug dictionary   MORPHINE                            OXYCODONE                            OXYMORPHONE                            METHADONE                            BUPRENORPHINE                            HYDROMORPHONE                            CODEINE                            HYDROCODONE          prev   None     for row in data          if prev is None or prev  row 11               drug dictionary append row 11        return drug dictionary   I later want to be able to access the entirr set of entries in  for example   MORPHINE     How do I append a number into the drug dictionary  How do I later traverse through each entry

User · Answer

how do i append a number into the drug dictionary   Do you wish to add  a number  or a set of values    I use dictionaries to build associative arrays and lookup tables quite a bit   Since python is so good at handling strings   I often use a string and add the values into a dict as a comma separated string  drug dictionary        drug dictionary   MORPHINE                OXYCODONE                OXYMORPHONE                METHADONE                BUPRENORPHINE                HYDROMORPHONE                CODEINE                HYDROCODONE        drug to update    MORPHINE   try      oldvalue   drug dictionary drug to update   except      oldvalue         to increment a value     try         newval   int oldval         newval    1    except         newval   1       drug dictionary drug to update      s    newval    to append a value       try         newval   int oldval         newval    1    except         newval   1       drug dictionary drug to update      s  s     oldval newval     The Append method allows for storing a list of values but leaves you will a trailing comma  which you can remove with   drug dictionary drug to update   -1    the result of the appending the values as a string means that you can append lists of values as you need too and   print    s    s       drug to update  drug dictionary drug to update      can return    MORPHINE   10 5 7 42 12

User · Answer

You should use append to add to the list  But also here are few code tips   I would use dict setdefault or defaultdict to avoid having to specify the empty list in the dictionary definition   If you use prev to to filter out duplicated values you can simplfy the code using groupby from itertools Your code with the amendments looks as follows   import itertools def make drug dictionary data       drug dictionary          for key  row in itertools groupby data  lambda x  x 11            drug dictionary setdefault key     append row         return drug dictionary   If you don t know how groupby works just check this example    gt  gt  gt  list key for key  val in itertools groupby  aaabbccddeefaa      a    b    c    d    e    f    a

User · Answer

It sounds as if you are trying to setup a list of lists as each value in the dictionary  Your initial value for each drug in the dict is     So assuming that you have list1 that you want to append to the list for  MORPHINE  you should do   drug dictionary  MORPHINE   append list1    You can then access the various lists in the way that you want as drug dictionary  MORPHINE   0  etc   To traverse the lists stored against key you would do   for listx in drug dictionary  MORPHINE       do stuff on listx

User · Answer

Just use append   list1    1  2  3  4  5  list2    123  234  456  d     a        b       d  a   append list1  d  a   append list2  print d  a

User · Answer

You can use the update   method as well d     quot a quot   2  d update  quot b quot   4  print d      quot a quot   2   quot b quot   4

User · Answer

To append entries to the table   for row in data      name             figure out the name of the drug     number           figure out the number you want to append     drug dictionary name  append number    To loop through the data   for name  numbers in drug dictionary items        print name  numbers

User · Answer

If you want to append to the lists of each key inside a dictionary  you can append new values to them using   operator  tested in Python 3 7    mydict     a       b      print mydict  mydict  a       1 3  mydict  b       4 6  print mydict  mydict  a       2 8  print mydict    and the output     a        b         a    1  3    b    4  6     a    1  3  2  8    b    4  6     mydict  a   extend  1 3   will do the job same as   without creating a new list  efficient way

User · Answer

vowels     a   e   i   o   u    create a list of vowels   my str     this is my dog and a cat     sample string to get the vowel count count      fromkeys vowels 0   create dict initializing the count to each vowel to 0                                                                     for char in my str         if char in count           count char     1    print count

[python] Appending values to dictionary in Python

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