Week6-LetterFreq

#sol. in python

import numpy as np

def letterFrequency(filename):
    # Computes the frequency of each letter, a to z, case insensitive
    # in the text file (filename given as input)

    # Define alphabet
    alphabet = "abcdefghijklmnopqrstuvwxyz"

    # Read file into string
    filein = open(filename, "r")
    lines = filein.readlines()
    text = "".join(lines)

    # Convert to lower case
    text = text.lower()

    # Compute number of occurencies
    occur = np.zeros(26)
    for i in range(26):
        occur[i] = text.count(alphabet[i])

    # Compute frequencies in percent
    freq = occur / np.sum(occur) * 100
    return freq
    
    
 #sol. in matlab
 
 function freq = letterFrequency(filename)
% Computes the frequency of each letter, a to z, case insensitive
% in the text file (filename given as input)

% Define alphabet
alphabet = 'abcdefghijklmnopqrstuvwxyz';

% Read file into string
text = fileread(filename);

% Convert to lower case
text = lower(text);

% Compute number of occurencies
occur = zeros(1, 26);
for i = 1:26
    occur(i) = sum(text == alphabet(i));
end

% Compute frequencies in percent
freq = occur / sum(occur) * 100;



#sol. in R

letterFrequency <- function(filename) {
    # Computes the frequency of each letter, a to z, case insensitive
    # in the text file (filename given as input)

    # Define alphabet
    alphabet <- "abcdefghijklmnopqrstuvwxyz"

    # Read file into string
    lines <- readLines(filename)
    text <- paste0(lines, collapse="")

    # Convert to lower case
    text <- tolower(text)

    # Convert string to character vector
    textvec <- strsplit(text, "")[[1]]

    # Compute number of occurencies
    occur <- rep(0, 26)
    for (i in 1:26) {
        occur[i] <- sum(textvec == substring(alphabet, i, i))
    }

    # Compute frequencies in percent 
    freq <- occur / sum(occur) * 100
    return(freq)
}