I was delighted to read your recent blog employing a "heat map" to visually present digram frequency data, obtained from Norvig"s update of my 1965 tables. Since you indicate you plan to continue this type of analysis, may I suggest that it might be highly useful and instructive to apply this technique, not just to the total digram frequency counts, as you have done, but also to those frequency columns in the tables which are "KEYED OFF" of word length and letter position. If you were to do this with the Norvig tables you would have 36 additional "heat maps", providing easy visual comparisons relating to word length and letter position combinations, which have proved to be highly significant components for research, since the publication of my original tables. Also, do you plan to go beyond digrams to trigrams, tetragrams, pentagrams etc., all of which would have significant implications for cryptanalysis.

I look forward to your reaction to these suggestions.