A resource for finding letter frequencies with certain restrictions

Question

I'm looking for a resource where I can see the frequencies of letters with respect to their position in a word and the length of the word. I'd also like to see the frequencies of different combinations of letters, as in "how often does a word start with an e and end with an a".

To be extra clear: the most common letter in English is e, but the most common third letter is...? And what about the most common fourth letter in five-letters-long words?

I'm specifically interested in the frequencies within dictionaries.

Answer 1

For specific combinations of letters within words of a specific length, use a crossword solver.

For a bit more flexibility, you can use a regex dictionary. (Of course, this means you have to know or learn regex... not trivial.) Here's the regex for "how often does a word start with an e and end with an a":

^e[^\s]*a$

For your other use case, it's a bit more complicated but you could string together several tools. First, you get (for example) the fourth character of every five letter word, which could be done using Regex101 with a wordlist and the regex ^...(.).$ (must have multi line matching and maybe case insensitive modifiers, also maybe use [a-z] in the regex instead of ., since the latter matches spaces and hyphens), then export only the matches. Then, feed the results to something that tells you the most common occurrence in the list.

Answer 2

English character frequencies are amenable to online search. See for example The frequency of the letters of the alphabet in English.

Your second problem of frequencies of position in a word of specified length has to be coded. As a coding question it belongs on another site. Nevertheless, it is impossible to fit this into the format of a comment, so I have answered it here only so as to give a pointer to how it may be done.

One of the many ways is to code in Mathematica (see the sister Stack Exchange site) and to use the built-in dictionary of almost a hundred thousand words.

Here is the answer to your specific 5 word & 4th character query but it is simple to make a routine to examine any length (n) of word and any character (m) within the words:

From which you may see that the most common fourth letter in five letter words is "e".

(My coding is pretty basic and could be briefer in the hands of a more competent Mathematica user)

Here is the text version of the code:

(*Look up all words in the Mathematica Dictionary and convert to  lowercase*)  
allwords = ToLowerCase[DictionaryLookup[]];  
(*Find all words with length n*)  
words[n_] := Select[allwords, StringLength[#] == n &];  
(*Find the mth character in the list of n letter words*)  
wordNcharacterM[n_, m_] := Map[Take[#, {m}] &, Characters[words[n]]];  
(*Total number of characters found*)  
totalChars[n_, m_] := 
  Total[Tally[wordNcharacterM[n, m]]\[Transpose][[2]]];  
(*Tabulate the results of a tally of the numbers of characters found*)  
table[n_, m_] := 
  Map[{#[[1]], #[[2]], N[100 #[[2]]/totalChars[n, m], 2]} &, 
   Tally[wordNcharacterM[n, m]]];  
(*Construct a title table*)  
tableOut[n_, m_] := 
  Join[{{{"word", n}, {"character", m}, " "}}, {{{"letter"}, "number",
      "%"}}, table[n, m]];  
(*Present the table*)  
outputWordNMCharacterM[n_, m_] := 
  Join[{{{"word", n}, {"character", m}, " "}}, {{{"letter"}, "number",
      "%"}}, ReverseSort[table[n, m], #1[[2]] < #2[[2]] &]];
(*Present the table*)
outputWordNMCharacterM[n_, m_] := 
  Join[{{{"word", n}, {"character", m}, " "}}, {{{"letter"}, "number",
      "%"}}, ReverseSort[table[n, m], #1[[2]] < #2[[2]] &]];
(*Present the table*)
outputWordNMCharacterM[n_, m_] := 
  Join[{{{"word", n}, {"character", m}, " "}}, {{{"letter"}, "number",
      "%"}}, ReverseSort[table[n, m], #1[[2]] < #2[[2]] &]];
(*Present the table for five letter words position 4*)
outputWordNMCharacterM[5, 4] // TableForm