Pharo Script of the Day: Colorizing nucleotides

Some days ago I experimented a bit to colorize a random DNA sequence given an alphabet and the desired sequence size, with a little help of BioSmalltalk. This is what I've got:

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| text attributes | text := ((BioSequence forAlphabet: BioDNAAlphabet) randomLength: 6000) sequence asText. attributes := Array new: text size. 1 to: text size do: [ : index |   attributes at: index put: {   (TextColor color: (BioDNAAlphabet colorMap at: (text at: index))) }  ]. text runs: (RunArray newFrom: attributes). text.

I built a color map for every nucleotide, based on the alphabet size. This is because in biological sequences (proteins, DNA, RNA) you have a different set of letters.

I should say I don't like the final result. Specially the lack of column alignment:

This seems to persist even trying other attributes

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| text attributes | text := ((BioSequence forAlphabet: BioDNAAlphabet) randomLength: 6000) sequence asText. attributes := Array new: text size. 1 to: text size do: [ : index |   attributes at: index put: {   (TextColor color: (BioDNAAlphabet colorMap at: (text at: index))) .   (TextKern kern: 4) }  ]. text runs: (RunArray newFrom: attributes). text.

Maybe efforts in Bloc would make it easier for aligning text.