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    The AHEI layout (an improved Dvorak-like layout)

    • Started by leCri
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    • Registered: 15-Apr-2022
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    Since I started using the Dvorak layout a couple of years ago, my interest for different keyboard layouts has increased significantly. I have tried out Colemak as well, although I never reached a high speed with it, but at that point I felt that I personally preferred the Dvorak layout. My favorite feature with Dvorak is the high degree of hand alteration, and in particular that all the vowels are on the left-hand side, while the common consonants are on the right-hand side. After having gotten used to that, I didn't want to give it up. Therefore, I started to think about ways that the Dvorak layout could be modified, to get a better Dvorak-like layout, while maintaining the feature I like with Dvorak. I looked at several other popular layouts for inspiration, and tried out different modifications, guided by letter and bigram frequencies, to minimize consecutive finger use and trying to make the most common bigrams comfortable to type. After a lot of thought and testing, this resulted in the AHEI layout (named after the home row). It performs better than several popular and optimized layouts (including the Dvorak and Colemak layouts) according to two different keyboard layout analyzers. The most common letters are easy to reach from the home position, and common two-letter combinations are rarely typed with the same finger.

    The layout should be easy to learn if you already are a Dvorak typist, since Dvorak was the starting point. 11 letters have the same positions as on Dvorak, and most of the other letters are close to where they are positioned on a Dvorak keyboard. Only two letters, H and Q, switch sides. The layout solves the Dvorak issue of having to stretch for the common letter I, while maintaining comfortable typing of the common bigram OU. It also decreases the load on the right pinky finger, and removes the moderately frequent letter F from its unfavourable position on the Dvorak keyboard. After having used this layout for about half a year, I am still quite satisfied with it (although I of course, every now and then, think about how it could be further improved). So I wanted to share it, including my thoughts and insights gained while working with it, in case some of it could be interesting to someone else.

    Image of the layout, including some performance indicators: The AHEI layout


    When looking at the letter frequency heat map for the Dvorak keyboard, it seems that the most obvious improvement would be to switch I and U, since I is a much more frequent letter, and thus should be placed at one of the eight home keys, that don't require any stretch or lateral movement. An argument for not doing this is that OU is the most common vowel bigram, and this would be less comfortable to type if I and U were switched. The second most common criticism against the Dvorak keyboard is that it puts too much effort on the weak right pinky finger, which is assigned to two common letters: S and L.

    For the most popular alternative keyboard layouts, Dvorak and Colemak, it seems like the keys on the home row — including the keys in the middle columns — are viewed as the best positions. Some people argue that the lateral movement to reach the middle column requires more effort than moving some fingers up and down, and that the middle columns thus should be de-emphasized. This approach has been taken for many newer layouts, such as the Workman layout and the Colemak Mod-DH layout. Some computer-optimized layouts such as the MTGAP layout and the very recent Engram layout even avoid putting letters at all in the middle columns, and use some or all of those keys for punctuation marks.

    I have tried to use ideas from these different layouts it order modify the Dvorak layout and improve it. I want to keep the high degree of hand alteration, which is a feature I like with Dvorak, and therefore I want to keep all the vowels on the left-hand side, and most of the common consonants on the right-hand side. I also prefer to keep the keys close to their positions on Dvorak, since that's what I'm used to, and it would thus be easier to learn the new layout. The main objective is to find a design such that all common bigrams (two-letter combinations) are comfortable to type. We would for example like to avoid having to type common bigrams with the same finger.

    The best keys are obviously the eight home keys, so we would like to place some of the most common letters there. Personally, I think that the second best keys are the ones above the middle and ring fingers, and the third best are probably above or under the index finger. The reason that the keys above the index fingers aren't included in the second category is that I find them slightly harder to reach on a classical keyboard, when I have my hands slightly angled, for a more ergonomic wrist position. So, on the 12 best (in my opinion) keys, I would like to fit most of the common letters.

    One solution for the U-I problem, that is used in both the MTGAP and the Engram layout, is to place O above the E key, and U next to it. In this way, we can both fit the common letter I among the home keys, and at the same time type the common bigram OU comfortably, while keeping O at one of the second best keys. The second most common vowel bigram IO is also comfortable to type with this solution (more so than on Dvorak, where it requires a stretch). This leaves us with one free spot among the left-hand home keys. Since there are more common consonants than good positions on the right-hand side, it would make sense to move one of the consonants to the now free good spot on the left-hand side. The most common English bigram is TH, which, I assume, is why these letters are placed next to each other on Dvorak. However, after TH, we usually have a vowel, and most commonly E. HE is the second most common bigram. Thus, one idea is to move H to the left-hand side, so that combinations with E and other vowels are easy to type. Putting H on the old O-spot gives HE a nice inward roll, and HA, HO and HI are also nice and easy to type. At the same time, we have freed up one of the good spots on the right-hand side, so that we have more room among the good keys there for the common consonants.

    The next step is to rearrange the consonants on the right-hand side so that the most frequent ones are on the best keys, while avoiding that common bigrams are typed with the same finger (i.e. keeping consecutive finger use low). After having tried out many options, I ended up with the result in the linked image. The 11 most common letters, ETAOINSHRDL, all have a frequency above 4%, while the rest of the letters have a frequency of less than 3%. All these letters are now fitted into the 12 best positions on the keyboard.

    One of the worst positions on a standard staggered keyboard, among the letter keys, is probably the Dvorak F position (QWERTY Y), since it requires a long stretch. Therefore, I also made sure to remove the quite common letter F (2.2%) from there, and replace it with the second least common letter Q (0.1%). Also note that the finger assignments on the left-hand bottom row are displaced one step to the left, in accordance with the angle mod used for the Colemak Mod-DH layout, for a more ergonomic typing posture. The J has been moved away one step further from K, compared to Dvorak, to avoid having to type bigrams with J and a vowel with the same finger. I also incorporated the brilliant idea from Colmak of turning the caps lock key into a backspace key.

    To evaluate the layout, I mainly used the keyboard layout analyzer http://patorjk.com/keyboard-layout-analyzer. The new layout scores higher than all the ones that I have compared with, including Dvorak, Colemak, MTGAP and the newest Engram layout, for all of the three provided sample texts. These include the first chapter of Alice in Wonderland (results shown in the image), a list of the most commonly used words, and a list of most commonly used SAT words. The alteration between the hands for the first text is almost identical to the result for Dvorak, while it is significantly lower for Colemak, and slightly lower for the MTGAP and Engram layouts.

    Also with the analyzer https://colemakmods.github.io/mod-dh/analyze.html (where a low score is better), it gets a better score (1.77) than Dvorak (1.92), Colemak (1.84) and MTGAP (1.79). This analyzer uses a corpus with books from Project Gutenberg for evaluation (the same as used by the carpalx optimizer). The result here also shows that the AHEI layout is better at avoiding frequent same-finger bigrams than the Dvorak layout (which is seen by the first analyzer as well, by the diagram included in the image). The most common same-finger letter bigrams for Dvorak are GH (0.34%), CT 0.20%, RN (0.16%) and UP (0.16%). For the new layout, the top list instead consists of KI (0.13%), RM (0.10%), UI (0.10%), SC (0.10%), of which KI and UI are present in the Dvorak layout as well. Furthermore, the distribution between the hands is a bit more even for AHEI (left 51.2%, right 48.8%), compared to Dvorak (left 45.3%, right 54.7%).

    Finally, I also made a Swedish version of the layout, since I type a lot in Swedish as well. Like the SvDvorak layout, I have kept most of the non-letter keys as in the Swedish QWERTY layout, and added the three extra letters in the Swedish alphabet. Trying it out with the first analyzer, using some news articles in Swedish, it also outperforms SvDvorak and a Swedish Colemak variant (and, needless to say, the Swedish QWERTY layout).

    After having given a lot of thought to this, and reaching a result that seems rather satisfying, I wanted to share my thoughts and results, in case that it could benefit someone else as well. It would be fun if someone else either wanted to try it out, or could use the ideas to construct a layout that suits them.

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    • From: UK
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    Nice, it looks like you've done your research and come up with a decent Dvorak alternative. The heatmap is nicely clustered around the easiest keys. I especially like that you have incorporated the Angle Mod into the basic design - it would seem that most people already use an angle-mod/angle-cheat style technique so it makes sense to design layouts which this in mind, for traditional keyboards at least. It's an often overlooked but IMO important consideration.

    For its target audience (i.e. people looking for an improved Dvorak), I can't see anything majorly wrong with it... but just to nitpick anyway :-P ...
    - M is a middle-ranking key so I'm not keen on it's top-row pinky pinky position, albeit a bit better than Dvorak's L. Arguably you could switch M with something like W, V, or even Z!
    - PH on the same finger looks odd, you'd expect that to be a common bigram, but the stats seem to suggest it's not too bad.
    - I'm surprised to see S on a home index-finger key, as being a common pluralizer, you'd expect a lot of SFBs from this decision.
    - Although you say you like the upper ring and index fingers, I think you may be underestimating the goodness of the lower index finger keys (Qwerty C and M, assuming angle mod). Maybe your hands are higher up the keyboard than mine, but still, the K spot feels a bit of a wasted opportunity.

    Have you been using it yourself and how are you finding it?

    Last edited by stevep99 (17-Apr-2022 15:42:12)

    Using Colemak-DH with Seniply.

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    Thanks for your thoughts and feedback, I really appreciate it! I agree that the angle mod is a nice idea. It's hard to switch back from it once you have started getting used to it. I tried to combine as many good ideas from different sources as I could in the design.

    M is a middle-ranking key so I'm not keen on it's top-row pinky pinky position, albeit a bit better than Dvorak's L. Arguably you could switch M with something like W, V, or even Z!

    M is indeed one of the key positions that I'm least satisfied with. However, I think that I would consider the chosen position to be better than both the Z position and probably also the V position. In addition, I would like to keep V on the bottom row, and close to C, to make the copy-paste shortcuts slightly more comfortable (although it would be even nicer to keep them on the left-hand side). Whether the M position is better than the Z position could of course depend on your typing style, but since I use a standard staggered keyboard, I usually have my right hand in a rather large angle, where I spontaneously feel that it is a little easier to reach the M key than the Z key. On the other hand, switching M and W is one of the last changes I considered. I did actually try out that variant for a little while, but chose to switch back again. I think that my reasoning was that it felt nice to have most of the most common letters on the middle or upper row, and that this would make bigrams with M and D/L easier to type. However, when looking it up, it seems that these bigrams aren't that common, so that might not be a good argument. The reason that it felt slightly better might have been simply that I already had gotten used to it, and didn't give the modification enough time.

    Looking at letter frequencies, the difference between M and W isn't that big (2.6% vs. 2.4%), so considering only that, it shouldn't make a lot of difference to switch M and W. However, from a bigram point of view, the difference actually seems to be significant. Some of the most problematic bigrams with my design seem to be the ones with M and R. The problem isn't worse than the analogous problem with L and S on Dvorak, but not much better either. When looking at the bigram data, the frequency of same-finger bigrams involving M or W actually seems to be three times worse with my current design, compared to if we would switch M and W. So that appears to be a really good argument for making that change. So I will definitely give that modification a new chance now!

    PH on the same finger looks odd, you'd expect that to be a common bigram, but the stats seem to suggest it's not too bad.

    Given that we want to keep P on the left-hand side, all other positions would lead to same-finger bigrams with vowels, which all are more common than the PH bigram. The option would then be to switch P with some letter from the right hand side. The strongest candidate would probably be B, which also is an infrequent letter, but that would e.g. make the common bigram BE a bit less comfortable to type, I think. So I have chosen to keep the left-hand side consonants P, K, J from Dvorak on the left-hand side.

    I'm surprised to see S on a home index-finger key, as being a common pluralizer, you'd expect a lot of SFBs from this decision.

    Intuitively, I agree that it seems a bit odd, for that reason. However, the question is what options would be better? If we assume that we want to keep the five most common consonants on the eight home keys (H to the left and S, T, N, R to the right), and keep the other keys as they are, then the alternative would be to replace S with T, H, N or R. Using the bigram data to compute same-finger bigram frequencies with the pairs S + G/Q/F/X/B/C, and analogously for T, H, N and R, gives that replacing S with T would be 2.1 times worse, replacing it with H (as on Dvorak) would be 2.7 times worse, replacing it with R would be 3.0 times worse, and replacing it with N would be 4.8 times worse. So S seems to be the best choice, given no other changes. In addition, the fact that S tends to appear at the end of words should entail more inward rolls with this placement of S, compared to placing it further away to the right.

    Although you say you like the upper ring and index fingers, I think you may be underestimating the goodness of the lower index finger keys (Qwerty C and M, assuming angle mod). Maybe your hands are higher up the keyboard than mine, but still, the K spot feels a bit of a wasted opportunity.

    I definitely think that the lower index finger keys at least are the best keys immediately after the upper index and ring fingers. That's why I have placed the thirteenth most common letter, C, on that position on the right-hand side, after having used 11 out of my 12 favorite keys plus another relatively good key, to place the 12 most common letters.

    However, on the left-hand side, the situation is a bit trickier. Although the K key is a good position in itself, the key has lower rank due to the fact that it is on the left-hand side, where as few consonants as possible should be placed. The main design principle, which is the feature that I like with Dvorak, is that all vowels should be on the left-hand side, and that all common consonants should be on the right-hand side. This gives a good amount of hand alteration, and a rather low number of same-finger bigrams. That's why only some of the most infrequent consonants, P, J and K, are the ones that appear on the left-hand side, except for H, which has been very carefully placed in a column with no vowels and to simplify typing the common bigrams HE and HA. The K key will cause same-finger bigrams with both I, U and Y, so we wouldn't like to change it for a more common consonant, I think. I also like to keep K on the left-hand side to simplify typing of the common bigram CK. As a side note, I actually use the K key quite a lot in practice, since I also do some typing in Swedish and German, where it's a much more common letter. But this is then with the cost of getting more KI and KU bigrams, so it's less optimal than for typing in English, with regard to that key.

    Have you been using it yourself and how are you finding it?

    I have been using it full-time for about half a year now, and it's the nicest layout I have used so far, in my opinion, so I'm quite satisfied with it, although I'm still looking for possible modifications that could make it even better (of which the M-W switch definitely seems to be one). The feeling is quite similar to Dvorak, but it feels like less hand movement is needed, due to the deemphasizing of the middle columns. And I also have the impression that the slightly lower amount of same-finger bigrams makes the typing nicer. As with Dvorak, I really like the principle of placing all vowels to the left and all common consonants to the right. It feels like playing the piano, where the vowels are the base, and the consonants are the melody that should be mixed together with the base in a good way.

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    Here is a little update, two years later, if someone would be interested:

    I considered the feedback about switching M and W compared to the original design, since there seemed to be good arguments for it. After testing the switched version a bit longer, I decided to keep that change. Now I have been using the latest version for about two years, and I'm still happy with it. I have published some new comparisons and visualizations as well as the possibility to download and install it for macOS, in case someone would like to do that, here: https://github.com/christianrosdahl/ahei-keyboard.

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