Given this array = [ "3ab1", "2a0", "1abc2" ]
How do I sort it to [ "1abc2", "3ab1", "2a0" ]
(descending order of the last number)
and return [ 1,3,2 ]
. (the first numbers of each term)
When the last number and the next last number is not consecutive, the value returned should be 0.
[ "2x2", "3x0", "2x1" ] ==> [ 2, 2, 3 ]
[ "22x0", "3x9", "2x1" ] ==> [ 3, 0, 0, 0, 0, 0, 0, 0, 2, 22 ]
[ "2x4", "3x0" ] ==> [ 2, 0, 0, 3 ]
[ "axn", "bx(n-2)" ] ==> [ "axn", "0x(n-1)", bx(n-2) ] ==> [ a, 0, b ]
I was thinking of converting to the array to string, replacing the number and letters in front and then sorting the array. But I do not know how put the part that was replaced back to its original number. This is my attempt on returning the final array once it is sorted.
var ary = [ "1abc2", "3ab1", "2a0" ]; console.log(((ary.toString()).match(/\\d+(?!,)/g)).slice(0, -1));
I saw these questions on sorting arrays based on numbers but they do not seem to work for me.
Your question is a bit odd, but you can achieve this using map
and parseInt
:
var arr = [ "1abc2", "3ab1", "2a0" ]; var res = arr.map(function (i) { return parseInt(i); }); console.log(res);
A combination of sort and map should do the trick.
const ary = [ "1abc2", "3ab1", "2a0" ]; const newarray = ary .sort((a, b) => { return a[a.length - 1] < b[b.length - 1]; }) .map((a) => { return parseInt(a[0]); }); console.log(newarray);
The script below first sorts the array descending, based on the end-numbers,
and then returns only the start-numbers of the sorted array.
(I changed your numbers in the array to show that they can be longer than one digit.)
var array = ["31ab12", "20a40", "11abc27"]; array.sort(function(a,b) { function getEndNum(str) {for (var i=str.length-1; i>=0; --i) {if (isNaN(str.charAt(i))) {return str.substring(i+1);}}} //this function returns the end-number of the supplied string return getEndNum(b) - getEndNum(a); //sort array descendingly, based on the end-numbers }); console.log(array.map(function(a){return parseInt(a);})); //create a new array with only the start-numbers
You can use regular expression to get the numbers when using sort
and reduce
to get the result:
var array = [ "22x0", "3x9", "2x1" ]; var reS = /^\\d+/, // regexp for getting all digits at the start of the string reE = /\\d+$/; // regexp for getting all digits at the end of the string var result = array.sort(function(a, b) { // First: sort the array a = reE.exec(a); // get the last number from the string a b = reE.exec(b); // get the last number from the string b return b - a; // sort in a descending order }).reduce(function(res, str, i) { // Then: accumulate the result array var gap = reE.exec(array[i - 1]) - reE.exec(str); // calculate the gap between this string str and the last string array[i - 1] (gap = N_of_last_string - N_of_this_string) if(gap > 0) // if there is a gap while(--gap) res.push(0); // then fill it with 0s res.push(+reS.exec(str)); // push this string number return res; }, []); console.log("Sorted array:", array); // array is now sorted console.log("Result:", result); // result contain the numbers
In recent ECMAScript versions you can do it shortly using arrow functions like this:
let array = [ "22x0", "3x9", "2x1" ]; let reS = /^\\d+/, reE = /\\d+$/; let result = array.sort((a, b) => reE.exec(b) - reE.exec(a)) .reduce((res, str, i) => { let gap = reE.exec(array[i - 1]) - reE.exec(str); if(gap > 0) while(--gap) res.push(0); res.push(+reS.exec(str)); return res; }, []); console.log("Sorted array:", array); console.log("Result:", result);
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