How long does it take to type this?

Question

Introduction

I can type at a moderate pace, using the QWERTY keyboard layout. But if a word like yellowwooddoor has a ton of repeated letters, it takes a bit longer to type it. Even worse is when a word like "jump" has the same finger used for multiple different consecutive letters.

Here's how long it takes me to type letters on each finger (very unscientifically measured):

Columns are Finger name, keystrokes/second, seconds/keystroke, and the keys used by each finger

Typing same letter twice:       
L Pinky 5.2 0.1923076923 1qaz
L Ring  5   0.2          2wsx
L Mid   5.3 0.1886792453 3edc
L Index 5.5 0.1818181818 4rfv5tgb
R Thumb 6.5 0.1538461538 [space]
R Index 6.9 0.1449275362 6yhn7ujm
R Mid   6.3 0.1587301587 8ik,
R Ring  6.2 0.1612903226 9ol.
R Pinky 6.1 0.1639344262 0p;'

Typing different letter on same finger:     
L Pinky 4.6 0.2173913043
L Ring  4.6 0.2173913043
L Mid   4.5 0.2222222222
L Index 5.3 0.1886792453
R Index 5.4 0.1851851852
R Mid   5.1 0.1960784314
R Ring  5.2 0.1923076923
R Pinky 5.2 0.1923076923

Same data in CSV format.

It takes

.75 * (first_finger_same_letter_time + second_finger_same_letter_time) / 2

time to switch between two fingers.

Challenge

Given a string as input, how long does it take to type it?

• The "timer" starts the moment the first key is pressed and ends when the last key is pressed. You are just counting the time between keypresses.
• This is code-golf. Shortest answer in bytes wins.
• Submission can be either a complete program or function.
• Input and output any way you want it, stdin/out, function params, file, doesn't matter.
• Output should be accurate to at least 3 decimal places (+/- 0.001 for rounding error is fine). Leading 0. for numbers under 1 and trailing newline optional.
• Input will be a string that contains (lowercase) a-z, 0-9, space, semicolon, comma, period, and apostrophe.
• I always type spaces with my right thumb.
• I use the normal touch typing fingers (you can also look at the above table for finger-key mappings).
• Reference code used to generate test cases

Test cases

(empty string or any one-character string) - 0.000

aa - 0.192

fff - 0.364

fj - 0.123

the quick brown fox jumped over the lazy dog - 5.795

yellowwooddoor - 1.983

orangewooddoor - 1.841

jump on it, jump on it - 2.748

type on it, type on it - 2.549

abcdefghijklmnopqrstuvwxyz01234567890 ;,.' - 5.746

ok, this may not be the most accurate but it's in the ballpark, maybe within 30 percent or so. - 12.138

Answer 1

JavaScript (Node.js), 180 bytes

s=>(B=Buffer)(s).map(p=c=>(b='23841410645532207643205431765001333746443'[c*45%91%73%41]*2,t+=1/p?p-b?3/8*(g(b)+g(p)):g(b|c!=s):0,p=b,s=c),t=0,g=x=>10/B('4.2.5-75E6?3>4=4AA')[x])&&t

Try it online!

How?

Storing delays

The helper function \$g\$ takes an integer \$0\le x \le17\$ and returns a delay in seconds.

g = x => 10 / Buffer('4.2.5-75E6?3>4=4AA')[x]

The input \$x\$ is expected to be either:

• twice the bin number to get the delay for the same letter
• twice the bin number + 1 to get the delay for different letters

What is actually stored in the string '4.2.5-75E6?3>4=4AA' is the number of keystrokes per second multiplied by \$10\$ and converted to ASCII. Conveniently, all resulting characters are printable.

For instance, \$5.2\$ is stored as chr(52) which is '4'.

Converting a character to a key bin

We use the following hash function to convert an ASCII code \$c\$ to an index into a lookup table containing the bin numbers in \$[0..8]\$:

$$i = (((c\times 45) \bmod 91)\bmod 73)\bmod 41$$

Main loop

The total time \$t\$ is updated with:

t +=                        // add to t:
  1 / p ?                   //   if p is numeric:
    p - b ?                 //     if p is not equal to b:
      3 / 8 * (g(b) + g(p)) //       0.75 * (g(b) + g(p)) / 2
    :                       //     else:
      g(b | c != s)         //       g(b) if c == s or g(b + 1) otherwise
  :                         //   else (first iteration):
    0                       //     leave t unchanged

where \$p\$ is the previous bin and \$s\$ is the previous character.

Answer 2

Jelly, 78 bytes

“bk¶ŀqṣṁq*E’b25+45s2
Øq;"““;“,.'”Zṙ-ØD;"s2ẎW$€3,4¦ẎœiⱮQḢ€ị¢QƑịZƊQ3.75⁵Ḋ?÷$SµƝS

Try it online!

How?

“...’b25+45s2 - Link 1, keystrokes per 10 seconds: no arguments
“...’         - base 250 integer = 379310849477441257135820
     b25      - to base 25 = [16,7,7,1,5,1,8,0,10,8,24,9,18,6,17,7,20]
        +45   - add 45 = [61,52,52,46,50,46,53,45,55,53,69,54,63,51,62,52,65]
           s2 - split into twos
              - = [[61,52],[52,46],[50,46],[53,45],[55,53],[69,54],[63,51],[62,52],[65]]
             - For: 0...    1...    2...    3...    4...    6...    8...    9...    space

Øq;"““;“,.'”Zṙ-ØD;"s2ẎW$€3,4¦ẎœiⱮQḢ€ị¢QƑịZƊQ3.75⁵Ḋ?÷$SµƝS - Main Link: list of characters
                                                      µƝ  - for each neighbouring pair:
Øq                                                        -   qwerty = ["qwertyuiop","asdfghjkl","zxcvbnm"]
    ““;“,.'”                                              -   list of lists = ["",";",",.'"]
   "                                                      -   zip with:
  ;                                                       -     concatenate = ["qwertyuiop","asdfghjkl;","zxcvbnm,.'"]
            Z                                             -   transpose = ["qaz","wsx","edc","rfv","tgb","yhn","ujm","ik,","ol.","p;'"]
             ṙ-                                           -   rotate left -1 = ["p;'","qaz","wsx","edc","rfv","tgb","yhn","ujm","ik,","ol."]
               ØD                                         -   digits = "0123456789"
                  "                                       -   zip with:
                 ;                                        -     concatenate = ["0p;'","1qaz","2wsx","3edc","4rfv","5tgb","6yhn","7ujm","8ik,","9ol."]
                   s2                                     -   split into twos = [["0p;'","1qaz"],["2wsx","3edc"],["4rfv","5tgb"],["6yhn","7ujm"],["8ik,","9ol."]]
                            ¦                             -   sparse application...
                         3,4                              -   ...to indices: [3,4]
                       $€                                 -   ...do: last two links as a monad for each:
                     Ẏ                                    -     tighten
                      W                                   -     wrap in a list = [["0p;'","1qaz"],["2wsx","3edc"],["4rfv5tgb"],["6yhn7ujm"],["8ik,","9ol."]]
                             Ẏ                            -   tighten = ["0p;'","1qaz","2wsx","3edc","4rfv5tgb","6yhn7ujm","8ik,","9ol."]
                                 Q                        -   de-duplicate (the neighbouring letters)
                                Ɱ                         -   map with:
                              œi                          -     multi-dimensional index-into    e.g. "fj" -> [[5,3],[6,7]]
                                                          -     (note <space> is not there so yields an empty list)
                                  Ḣ€                      -   head of each                                -> [5,6]
                                                          -     (...and the head of an empty list is 0)
                                     ¢                    -   call the last Link (1) as a nilad
                                    ị                     -   index-into                                  -> [[55,53],[69,54]]
                                                          -     (...and 0 indexes into the rightmost entry)
                                          Ɗ               -   last three links as a monad:
                                       Ƒ                  -     invariant under?:
                                      Q                   -       de-duplicate (1 if so, else 0)
                                         Z                -       transpose                               -> [[55,69],[53,54]]
                                        ị                 -       index-into                              -> [55,69]
                                           Q              -   de-duplicate                                -> [55,69]
                                                    $     -   last two links as a monad:
                                                  ?       -     if...
                                                 Ḋ        -     ...condition: dequeue
                                            3.75          -     ...then: 3.75
                                                ⁵         -     ...else: 10                               -> 3.75
                                                   ÷      -     divide                                    -> [0.06818181818181818,0.05434782608695652]
                                                     S    -   sum                                         -> 0.12252964426877469
                                                        S - sum

Answer 3

05AB1E, 92 86 bytes

Îü)v•δ'ā∍ë*8U¾Ã•₂в45+2ô9ÝÀžV€Sζ‚ø˜ð",.;'"S.;ykD4/ïD3›-D4›-‚©θ讀ËOUεXè}T/zX_iO3*8/ëθ]O

Try it online or verify all test cases.

Explanation:

Î                     # Push 0 and the input-string
 ü)                   # Create all pairs of the (implicit) input-string
                      # (which will be [] if the input-string is of length 0 or 1)
                      #  i.e. "ab d" → ["a","b"],["b"," "],[" ","d"]]
   v                  # Loop over these pairs `y`:
    •δ'ā∍ë*8U¾Ã•     '#  Push compressed integer 307264255556527588774514
      ₂в              #  Converted to Base-26 as list: [7,1,5,1,8,0,10,8,24,9,18,6,17,7,16,7,20]
        45+           #  Add 45 to each: [52,46,50,46,53,45,55,53,69,54,63,51,62,52,61,52,65]
           2ô         #  Split into parts of size 2: [[52,46],[50,46],[53,45],[55,53],[69,54],[63,51],[62,52],[61,52],[65]]
    9Ý                #  Push list [0,1,2,3,4,5,6,7,8,9]
      À               #  Rotate it once to [1,2,3,4,5,6,7,8,9,0]
       žV             #  Push builtin ["qwertyuiop","asdfghjkl","zxcvbnm"]
         €S           #  Convert each to a list of characters
           ζ          #  Zip/transpose; swapping rows/columns, with space as default filler:
                      #   [["q","a","z"],["w","s","x"],["e","d","c"],["r","f","v"],["t","g","b"],["y","h","n"],["u","j","m"],["i","k"," "],["o","l"," "],["p"," "," "]]
            ‚ø        #  Pair it with the digit list, and zip/transpose again
              ˜       #  Then flatten this entire list:
                      #   ["1","q","a","z","2","w","s","x","3","e","d","c","4","r","f","v","5","t","g","b","6","y","h","n","7","u","j","m","8","i","k"," ","9","o","l"," ","0","p"," "," "]
               ð",.;'"S.;
                      #  Replace the four spaces with [",", ".", ";", "'"] in order
     yk               #  Get the indices of the characters in the pair `y` in this list
                      #   i.e. ["b"," "] → [19,-1]
        4/            #  Divide both by 4
                      #   i.e. [19,-1] → [4.75,-0.25]
          ï           #  Floor the decimals to integers
                      #   i.e. [4.75,-0.25] → [4,-1]
           D3›-       #  If an index is larger than 3: decrease it by 1
                      #   i.e. [4,-1] → [3,-1]
               D4›-   #  If an index is now larger than 4: decrease it by 1 again
       D           ‚  #  Pair it with the original index
                      #   i.e. [[19,-1],[3,-1]]
                    © #  And save it in the register (without popping)
     θè               #  Then use the last of the two to index into the list of pairs
                      #   i.e. [3,-1] → [[55,53],[65]]
       ®€Ë            #  Check for each pair in the register if they're equal
                      #   i.e. [[19,-1],[3,-1]] → [0,0]
          O           #  Take the sum of that
           U          #  And pop and store it in variable `X`
            ε  }      #  Map the pairs in the list to:
             Xè       #   The `X`'th value in the pair
                      #    i.e. [[55,53],[65]] and `X`=0 → [55,65]
     T/               #  Divide each by 10
                      #   i.e. [55,65] → [5.5,6.5]
       z              #  And take 1/value for each
                      #  i.e. [5.5,6.5] → [0.181...,0.153...]
        X_i           #  If variable `X` was 0:
           O          #   Take the sum of these decimal values
                      #    i.e. [0.181...,0.153...] → 0.335...
            3*8/      #   Multiply it by 3, and then divide it by 8
                      #    i.e. 0.335... → 0.125...
          ë           #  Else:
           θ          #   Pop the pair of decimal values, and only leave the last one
   ]                  # Close both the if-else statement and the loop
    O                 # And take the sum of the stack
                      # (which is output implicitly as result)

See this 05AB1E tip of mine (sections How to compress large integers? and How to compress integer lists?) to understand why •δ'ā∍ë*8U¾Ã• is 307264255556527588774514 and •δ'ā∍ë*8U¾Ã•₂в is [7,1,5,1,8,0,10,8,24,9,18,6,17,7,16,7,20].