I have an array with eight values inside it. I have another array with the same amount of values. Can I simply substract these arrays from each other?
Here is an example:
var firstSet =[2,3,4,5,6,7,8,9]
var secondSet =[1,2,3,4,5,6,7,8]
firstSet - secondSet =[1,1,1,1,1,1,1,1] //I was hoping for this to be the result of a substraction, but I'm getting "undefined" instead of 1..
How should this be done properly?
Like this:
var newArray = [];
for(var i=0,len=firstSet.length;i<len;i++)
newArray.push(secondSet[i] - firstSet[i]);
Note that it is expected for secondSet to have the same number (or more) as firstSet
Give this a try:
for (i in firstSet) {
firstSet[i] -= secondSet[i];
}
var i (implicitly creating a global var) and stackoverflow.com/questions/500504/…. -1 sorry.for ... in with Arrays in js.Element-wise subtraction should work:
var result = [];
for (var i = 0, length = firstSet.length; i < length; i++) {
result.push(firstSet[i] - secondSet[i]);
}
console.log(result);
var firstSet = [2,3,4,5,6,7,8,9]
var secondSet = [1,2,3,4,5,6,7,8]
var sub = function(f, s) {
var st = [], l, i;
for (i = 0, l = f.length; i < l; i++) {
st[i] = f[i] - s[i];
}
return st;
}
console.log(sub(firstSet, secondSet));
What you're after is something like Haskell's "zipWith" function
"zipWith (-) xs ys", or in Javascript syntax "zipWith(function(a,b) { return a - b; }, xs, ys)" returns an array of [(xs[0] - ys[0]), (xs[1] - ys[1]), ...]
The Underscore.js library has some nice functions for this kind of thing. It doesn't have zipWith, but it does have "zip", which turns a pair of arrays xs, ys into an array of pairs [[xs[0], ys[0]], [xs[1], ys[1]], ...], which you can then map a subtraction function over:
_.zip(xs, ys).map(function(x) { return x[0] - x[1]; })
You may find this interesting https://github.com/documentcloud/underscore/issues/145
