How to replace all roman numbers in a string for the arabic equivalent?
I have a list of all Shakespeare sonnets and I'm making a function to search for each sonnet. However, I want to be able to search them using arabic numbers (for example "/sonnet 122". The .txt is formatted this way:
I
This is a sonnet
II
This is a second sonnet
I am using node right now to try to do it, but I've been trying since yesterday to no avail. My last attempts yesterday were using the 'replace' method as such:
'use strict';
//require module roman-numerals, which converts roman to arabic
var toArabic = require('roman-numerals').toArabic;
//require file-handling module
var fs = require('fs');
fs.readFile('sonn.txt', 'utf8', function (err,data) {
if (err) {
console.log(err);
} else {
var RN = /[A-Z]{2,}/g;
var found = data.match(RN); //finds all roman numbers and puts them in an array
var numArr = [];
for (var i = 0; i < found.length; i++ ){
numArr.push(toArabic(found[i])); //puts all arabic numbers in numArr
}
for (var e = 0; e < found.length; e++){
data.replace(found, found.forEach((x, i)=> {
toArabic(x)
}
});
Then I tried replacing them with:
data.replace(found, function(s, i){
return numArr[i];
});
Then I tried with a for loop. I didn't keep that code, but it was something like:
for(var i=0;i<found.length;i++){
data.replace(found, numArr[i]);
}
The last code replaces each number and then erases the data and replaces the next number as such:
replace(abc, 123) -> 1bc, a2c, ab3
How do I make it iterate each occurrence in the data and keep it? Then saving it to a new txt should be easy.
(Also, my RegExp only finds multiple character roman numbers to avoid replacing lonely I's that could be found at the end of a line.)
You have to write the replaced string back, and you could use a callback for replace()
'use strict';
var toArabic = require('roman-numerals').toArabic;
var fs = require('fs');
fs.readFile('sonn.txt', 'utf8', function (err,data) {
if (err) {
console.log(err);
} else {
data = data.replace(/[A-Z]{2,}/g, function(x) {
return toArabic(x);
});
}
});
Here are some more regular expressions to match romans
If you use String.prototype.replace , you can use your regular expression and a custom replacement function. You just need to return the value to use as a replacement, which is what toArabic does.
var data = 'InnThis is a sonnetnnIInnThis is a second sonnet';
//========================
var toArabic = (function () {
var forEach = Array.prototype.forEach;
/**
* Converts a roman number to its arabic equivalent.
*
* Will throw TypeError on non-string inputs.
*
* @param {String} roman
* @return {Number}
*/
function toArabic (roman) {
if (('string' !== typeof roman) && (!(roman instanceof String))) throw new TypeError('toArabic expects a string');
// Zero is/was a special case. I'll go with Dionysius Exiguus on this one as
// seen on http://en.wikipedia.org/wiki/Roman_numerals#Zero
if (/^nulla$/i.test(roman) || !roman.length) return 0;
// Ultra magical regexp to validate roman numbers!
roman = roman.toUpperCase().match(/^(M{0,3})(CM|DC{0,3}|CD|C{0,3})(XC|LX{0,3}|XL|X{0,3})(IX|VI{0,3}|IV|I{0,3})$/);
if (!roman) throw new Error('toArabic expects a valid roman number');
var arabic = 0;
// Crunching the thousands...
arabic += roman[1].length * 1000;
// Crunching the hundreds...
if (roman[2] === 'CM') arabic += 900;
else if (roman[2] === 'CD') arabic += 400;
else arabic += roman[2].length * 100 + (roman[2][0] === 'D' ? 400 : 0);
// Crunching the tenths
if (roman[3] === 'XC') arabic += 90;
else if (roman[3] === 'XL') arabic += 40;
else arabic += roman[3].length * 10 + (roman[3][0] === 'L' ? 40 : 0);
// Crunching the...you see where I'm going, right?
if (roman[4] === 'IX') arabic += 9;
else if (roman[4] === 'IV') arabic += 4;
else arabic += roman[4].length * 1 + (roman[4][0] === 'V' ? 4 : 0);
return arabic;
};
return toArabic;
})();
//====================
var RN = /[A-Z]{1,2}(?=n)/g;
var newData = data.replace(RN, toArabic);
document.body.innerText = newData;链接地址: http://www.djcxy.com/p/37234.html
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