Tool in Mylly: Relation algebra / Drop | fi

Drop selected attributes

The ”drop” operation projects an input relation to other than the selected attributes.

The input and output relations are represented as TSV files.


  • zero or more attributes

Attributes are presented as menus that list the attributes that the relation has. EMPTY indicates that the parameter is not used.

Selecting the same attribute more than once is harmless.

(Selecting all attributes produces a relation with no attributes. There are two such relations.)


The input relation consists of word forms annotated with sentence and token numbers and lemmas.

word tok sen lemma
on 1 3 olla
se 2 3 se
niin 3 3 niin
on 1 5 olla
ei 1 4 ei
ole 2 4 olla

When the sentence and token number are dropped, the two occurrences of olla as on melt into one record.

lemma word
ei ei
se se
niin niin
olla on
olla ole

When the sentence and token number and the word form itself are dropped, so only the lemma is kept, all three occurrences of olla melt into one record.


Related tools

  • keep
  • drop with count
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