问题
I'm trying to generate a string of 140 Characters based on probabilities of repetition from an input text. I already have an array with each valid character and in a different array probability of each char.
char[] array = [a, b, c, ...]
double[] array2 = [.1, .3, .4, ...]
I already read that I need to generate a random double from 0-1, but I don't get how to relate it to my arrays and generate a 140 char String. Just need help with that method, at least the explanation on how to do it.
Thanks in advance.
回答1:
Here is my implementation. If you have some questions let me know.
import java.util.Random;
public class MarkovChainTest {
private static char[] array = {'a', 'b', 'c', 'd'};
private static double[] array2 = {.1, .3, .4, .2};
public static void main(String[] args) {
System.out.println(generateString(array, normalizeToOne(array2), 140));
}
private static double[] normalizeToOne(double[] freqs) {
double sum = 0;
for (double freq : freqs)
sum += freq;
double[] ret = new double[freqs.length];
for (int i = 0; i < freqs.length; i++)
ret[i] = freqs[i] / sum;
return ret;
}
private static String generateString(char[] chars, double[] freqs, int length) {
return generateString(chars, freqs, length, new Random(System.currentTimeMillis()));
}
private static String generateString(char[] chars, double[] freqs, int length, Random rnd) {
StringBuilder ret = new StringBuilder();
for (int i = 0; i < length; i++)
ret.append(generateChar(chars, freqs, rnd));
return ret.toString();
}
private static char generateChar(char[] chars, double[] freqs, Random rnd) {
double val = rnd.nextDouble();
double sumOfPrevFreqs = 0;
for (int i = 0; i < chars.length; i++) {
if (sumOfPrevFreqs + freqs[i] >= val)
return chars[i];
sumOfPrevFreqs += freqs[i];
}
throw new IllegalStateException("Sum of frequencies (" + sumOfPrevFreqs + ") < " + val);
}
}
来源:https://stackoverflow.com/questions/32578239/markov-chains-random-text-based-on-probability-java