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5639 :: CountTable inconsistency?

• onde (orginal) [2019-12-04T18:02:37+01:00] view original

  Hi all,

  new forum member here. Please be forgiving.

  I think I discovered an inconsistency in CountTable. I couldn't find a way to delete a key (no del() implementation?!), so instead I set its value to 0 as recommended in this Stackoverflow Post. While the key now disappears from keys() it's still accounted for in len().

  Crude example:

  import tables
  
  let myString = "abracadabra"
  var letterFrequencies = toCountTable(myString)
  
  echo "BEFORE set 0"
  echo letterFrequencies
  echo "len ", len(letterFrequencies)
  for k, v in letterFrequencies.pairs():
    echo k, ":", v
  
  echo "AFTER set 0"
  letterFrequencies['a'] = 0
  echo letterFrequencies
  echo "len ", len(letterFrequencies)
  for k, v in letterFrequencies.pairs():
    echo k, ":", v

  Output:

  BEFORE set 0
  {'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 2}
  len 5
  a:5
  b:2
  c:1
  d:1
  r:2
  AFTER set 0
  {'b': 2, 'c': 1, 'd': 1, 'r': 2}
  len 5
  b:2
  c:1
  d:1
  r:2

  Is this the expected behaviour?

  Many thanks,

  Andreas

  PS: Nim version 1.0.4

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• Araq (orginal) [2019-12-04T20:20:19+01:00] view original

  Sounds like a bug to me but a count table is for counting. Setting a value to 0 is not counting, you're doing something else, use an ordinary table.

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• onde (orginal) [2019-12-05T01:59:20+01:00] view original

  Thanks Araq. Just to explain: I'm reading a user provided histogram, which is by right a CountTable, but I need to delete certain keys post ingestion. Since CountTable doesn't provide a del() I had to resort to setting the key to 0, which surfaced the bug above.

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• onde (orginal) [2019-12-05T02:05:45+01:00] view original

  Created an issue on Github

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