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Find min and max value in csv file

Looking to extend my javascript object, I want to find the minium and maximum of a multicolumn csvfile. I have looked up solutions but I cannot really grasp the right way. I found a solution here: Min and max in multidimensional array but I do not get an output.
My code that I have for now is here:
function import(filename)
{
var f = new File(filename);
var csv = [];
var x = 0;
if (f.open) {
var str = f.readline(); //Skips first line.
while (f.position < f.eof) {
var str = f.readline();
csv.push(str);
}
f.close();
} else {
error("couldn't find the file ("+ filename +")\n");
}
for (var i=(csv.length-1); i>=0; i--) {
var str = csv.join("\n");
var a = csv[i].split(","); // convert strings to array (elements are delimited by a coma)
var date = Date.parse(a[0]);
var newdate = parseFloat(date);
var open = parseFloat(a[1]);
var high = parseFloat(a[2]);
var low = parseFloat(a[3]);
var close = parseFloat(a[4]);
var volume = parseFloat(a[5]);
var volume1000 = volume /= 1000;
var adjusted_close = parseFloat(a[6]);
outlet(0, x++, newdate,open,high,low,close,volume1000,adjusted_close); // store in the coll
}
}

Edit
What if, instead of an array of arrays, you use an array of objects? This assumes you're using underscore.
var outlet=[];
var outletkeys=['newdate','open','high','low','close','volume','volume1000','adjusted_close'];
for (var i=(csv.length-1);i>0; i--) {
var a = csv[i].split(",");
var date = Date.parse(a[0]);
var volume = parseFloat(a[5],10);
outlet.push( _.object(outletkeys, [parseFloat(date,10) , parseFloat(a[1],10) , parseFloat(a[2],10) , parseFloat(a[3],10) , parseFloat(a[4],10) , parseFloat(a[5],10) , volume /= 1000 , parseFloat(a[6],10) ]) );
}
Then the array of the column 'open' would be
_.pluck(outlet,'open');
And the minimum it
_.min(_.pluck(outlet,'open'));
Edit2
Let's forget about underscore for now. I believe you need to get the maximum value on the second column, which is what you put in your open variable.
¿Would it help if you could have that value right after the for loop? For example
var maxopen=0;
for (var i=(csv.length-1); i>=0; i--) {
var a = csv[i].split(",");
var date = Date.parse(a[0]);
var newdate = parseFloat(date);
var open = parseFloat(a[1]);
maxopen=(open>maxopen)? open : maxopen; // open overwrites the max if it greater
...
...
outlet(0, x++, newdate,open,high,low,close,volume1000,adjusted_close);
}
console.log('Maximum of open is',maxopen);

Javascript string manipulation url

My problem is I am trying to extract certain things from the url. I am currently using
window.location.href.substr()
to grab something like "/localhost:123/list/chart=2/view=1"
What i have now, is using the index positioning to grab the chart and view value.
var chart = window.location.href.substr(-8);
var view = window.location.href.substr(-1);
But the problem comes in with I have 10 or more charts. The positioning is messed up. Is there a way where you can ask the code to get the string between "chart=" and the closest "/"?

var str = "/localhost:123/list/chart=2/view=1";
var data = str.match(/\/chart=([0-9]+)\/view=([0-9]+)/);
var chart = data[1];
var view = data[2];
Of course you may want to add in some validation checks before using the outcome of the match.
Inspired by Paul S. I have written a function version of my answer:
function getPathVal(name)
{
var path = window.location.pathname;
var regx = new RegExp('(?:/|&|\\?)'+name+'='+'([^/&,]+)');
var data = path.match(regx);
return data[1] || null;
}
getPathVal('chart');//2
Function should work for fetching params from standard get parameter syntax in a URI, or the syntax in your example URI

Here's a way using String.prototype.indexOf
function getPathVar(key) {
var str = window.location.pathname,
i = str.indexOf('/' + key + '=') + key.length + 2,
j = str.indexOf('/', i);
if (i === key.length + 1) return '';
return str.slice(i, j);
}
// assuming current path as described in question
getPathVar('chart');

You could split your string up, with "/" as delimiter and then loop through the resulting array to find the desired parameters. That way you can easily extract all parameters automatically:
var x = "/localhost:123/list/chart=2/view=1";
var res = {};
var spl = x.split("/");
for (var i = 0; i < spl.length; i++) {
var part = spl[i];
var index = part.indexOf("=");
if (index > 0) {
res[part.substring(0, index)] = part.substring(index + 1);
}
}
console.log(res);
// res = { chart: 2, view: 1}
FIDDLE

Javascript: How do I replace text between two delimiters?

var record = "HENRY|5|58|L581"
How do I change the above to:
record now equals "HENRY|Five|58|L581"
I know how to retrieve the index of the first '|' and the second '|' .. I know how to retrieve the number '5' into a string.
But I have no idea how to actually replace that 5 with the word Five.
The part |5| could be any number from 1-50

Something like that ?
record = record.replace('|5|', '|FIVE|');
Following edit :
To replace any number by FIVE, you can do
record = record.replace(/\|\d+\|/, '|FIVE|');
If you want to replace with something depending of the number (maybe you want TEN when the number is 10), then you'll have to do some work :
record = record.replace(/\|\d+\|/, function(str) {
var number = parseInt(str,10);
return 'FIVE'; // here build a new string and return it
});

You can do this, for example:
var record = "HENRY|5|58|L581"
var recordArray = record.split("|");
for (var i = 0; i < recordArray.length; i++) {
if (recordArray[i] === "5") {
recordArray[i] = "FIVE";
}
}
record = recordArray.join("|"); // or record = recordArray.toString();
Is this what you want to achieve?
UPDATE
If you want any number, you can set it into a function:
function changeNumber(textVar, valueToChange, replaceText) {
var recordArray = textVar.split("|");
for (var i = 0; i < recordArray.length; i++) {
if (recordArray[i] === valueToChange) {
recordArray[i] = replaceText;
}
}
return recordArray.join("|"); // or recordArray.toString();
}
See demo.

I presume you don't want to replace any number with "five", you want to replace with the actual string representing number.
var repl = [0, 1, ....];
var to = ["zero", "one", ...];
var recordArray = record.split("|");
for (var i = 0; i < recordArray.length; i++) {
recordArray[i] = to[indexOf(recordArray[i], repl)];
}
finStr = recordArray.join("|");

Writing a function that "solves" an equation

I want to write a function which will allow me to "solve" an equation in js.
what I want (not in a programming language):
function f(x) { 1 + x * x }
var z = 2
var y = f(z) //y will be 5 as a number
what I have written in JS:
function P(cfg) { ....
this.equation = "1 + x";
....};
P.prototype.eqn = function(x) {
var tmp = eval(this.equation);
return tmp;
};
....
P.prototype.draw = function() {....
for(var i = 0; i < z; i++)
ctx.lineTo(i, this.eqn(i));
....};
also I've read that using eval in a loop is probably not a good idea, but I have not figured out another way (yet) (JS beginner)...
The problem with this code is, that at least in FF the var tmp will STILL contain the string from this.equation instead of the calculated value.
I would appreciate any further insight very much!
Thank you for your time :)
EDIT: because my question was not formulated very well:
after the execution of line
var tmp = eval(this.equation);
the var tmp will hold a STRING which equals the string this.equation, instead of the desired solution y value.
Also I do not mean solve but evaluate, thanks for that tip :)

Based on your example, I'd say that you want to "evaluate an expression", rather than "solve an equation". For evaluating an expression, you can probably find many tutorials. I'll break it down in brief though. You need to do a few steps.
Starting with your string "1 + x * x", you need to break it into tokens. Specifically, break it down into: "1", "+", "x", "*", "x". At this point, you can substitute your variables ("x") for their literal values ("2"), giving you "1", "+", "2", "*", "2"
Now you need to parse the expression. Based on order of operations PEMDAS you need to create a tree data structure, where parenthetical clauses (stuff surrounded by parenthesis) are executed first, multiplication and division next, and then additions and subtraction last. Parsing is often not an easy task, and you may want to put together a simpler BNF grammar (though you can probably find a grammar for simple math expressions with some googling).
Next, walk the tree, depth first, evaluating the operations as you go up the tree. Once you get to the top of the tree, you have your solution.
If instead you want to "solve an equation", you're going to need something much more sophisticated, like Sage

I have used this expression evaluator before. It seemed to work very well. It allows you to pass expressions into a Parser that returns a function object that can then evaluate inputs.
var expr = Parser.parse("2 ^ x");
expr.evaluate({ x: 3 }); // 8
It supports trig functions (sin, cos, ect...) and other handy built in functions such as abs & ciel.
var expr = Parser.parse("sin(x/2) + cos(x/2)")
expr.evaluate({x: Math.PI / 2}); // 1
Examples: http://silentmatt.com/javascript-expression-evaluator/
Code: https://github.com/silentmatt/js-expression-eval
Note that this lib does not use eval().

Not sure I entirely understand your question but how about:
var makeFunctionOfX = function(src) {
return Function('x', 'return ' + src);
};
Then you can say things like:
var g = makeFunctionOfX('2 * x')
var y = g(3); // y contains 6
The great advantage of this over eval is that the Function we create has no magic ability to see variables in the scope (hence the need to explicitly pass it x as a parameter name).

Using eval is safe if you trust the input from the user, and works just fine. (I have no idea what you mean by "the var tmp will still have the string this.equation".)
function FuncCreator(eqn){ this.eqn = eqn }
FuncCreator.prototype.run = function(x,y,z){ return eval(this.eqn) }
var add1 = new FuncCreator('1+x');
var result = add1.run(41); // 42
var complex = new FuncCreator('Math.sin(x*y) / Math.cos(z)');
var result = complex.run(3,4,5); // -1.891591285331882
If you don't trust the user input, you'll need to actually parse the input and process it yourself. This is non-trivial.

You can use the expression parser from the math.js library and do something like this:
var parser = math.parser();
var f = parser.eval('function f(x) = 1 + x * x');
// use the created function f in expressions:
parser.eval('z = 2'); // 2
parser.eval('y = f(z)'); // 5
// or use the created function f in JavaScript:
var z = 2; // 2
var y = f(z); // 5
Creating functions in math.js is quite currently limited, loops and blocks needed to define more extensive functions are not yet supported.

This is an old thread, but I wrote this equation calculator, this doesn't solve algebraic equations though. There is however a function that will allow you to provide an array containing assigned variables. But this doesn't solve for variables that don't have an assigned value.
I probably haven't permuted every test case scenario, but it seems to work pretty decent.
Edit: This would have to be modified to handle negative numbers. Other than that... works fine.
Here is a fiddle
<!doctype html>
<html>
<head>
<title>Javascript Equation Calculator</title>
</head>
<body>
<input type="button" onclick="main()" value="calculate"><br>
<input type="text" id="userinput"><br>
<span id="result">Ready.</span><br>
<script>
function Calculator(){}
String.prototype.replaceLast = function (what, replacement)
{
var pcs = this.split(what);
var lastPc = pcs.pop();
return pcs.join(what) + replacement + lastPc;
};
function inS(substr, str){return (str.indexOf(substr) > -1);}
function arrayValueOrToken(arr, key, token)
{
if(key in arr)
{
return arr[key];
}
return token;
}
function reduceEquation(inputStr)
{
console.log("reduceEquation Executed-----");
while(hasNest(inputStr))
{
if(hasNest(inputStr))
{
inputStr = inputStr.replace(")(",')*(');
for(var i=0;i<=9;i++)
{
inputStr = inputStr.replace(i+"(",i+'*(');
inputStr = inputStr.replace(")"+i,')*'+i);
}
var s = inputStr.lastIndexOf("(");
var e = 0;
for(i=s;i,inputStr.length;i++){if(inputStr[i]==")"){e=i+1;break;}}
var eq = inputStr.substring(s,e);
var replace = eq;
eq = eq.replace(/[()]/g, '');
var substitution = solveEquation(eq);
inputStr = inputStr.replaceLast(replace,substitution);
}
}
return inputStr;
}
function solveEquation(eq)
{
console.log("solveEquation Executed-----");
eq = doFirstOrder(eq);
eq = doLastOrder(eq);
return eq;
}
function doFirstOrder(eq)
{
console.log("doFirstOrder Executed-----");
for(var i=0;i<eq.length;i++)
{
if(eq[i]=="*"){eq = solve(eq,"*");return doFirstOrder(eq);}
if(eq[i]=='/'){eq = solve(eq,'/');return doFirstOrder(eq);}
}
return eq;
}
function doLastOrder(eq)
{
console.log("doLastOrder Executed-----");
for(var i=0;i<eq.length;i++)
{
if(eq[i]=="+"){eq = solve(eq,"+");return doLastOrder(eq);}
if(eq[i]=="-"){eq = solve(eq,"-");return doLastOrder(eq);}
}
return eq;
}
function solve(eq, operator)
{
var setOp = operator;
console.log("solve Executed-----");
var buildEq = "",var1 = true,done = false,char="";
var operators = "+-/*";
var ops = operators.replace(operator, '').split('');
var a=ops[0];
var b=ops[1];
var c=ops[2];
for(var i=0;i<eq.length;i++)
{
char = eq[i];
switch(true)
{
case(char==operator):if(var1===true){var1 = false;}else{done = true;}break;
case(char==a):
case(char==b):
case(char==c):if(var1){char = ""; buildEq = "";}else{done = true;}
}
if(done){break;}
buildEq = buildEq + char;
}
var parts = parts = buildEq.split(operator);
var solution = null;
if(operator=="+"){solution = parseFloat(parts[0]) + parseFloat(parts[1]);}
if(operator=="-"){solution = parseFloat(parts[0]) - parseFloat(parts[1]);}
if(operator=="*"){solution = parseFloat(parts[0]) * parseFloat(parts[1]);}
if(operator=="/"){solution = parseFloat(parts[0]) / parseFloat(parts[1]);}
return eq.replace(buildEq, solution);
}
function hasNest(inputStr){return inS("(",inputStr);}
function allNestsComplete(inputStr)
{
var oC = 0, cC = 0,char="";
for(var i=0;i<inputStr.length;i++){char = inputStr[i];if(char=="("){oC+=1;}if(char==")"){cC+=1;}}
return (oC==cC);
}
Calculator.prototype.calc = function(inputStr)
{
console.log("Calc Executed-----");
inputStr = inputStr.replace(/ /g, "");
inputStr = inputStr.replace(/\\/g, '/');
inputStr = inputStr.replace(/x/g, "*")
inputStr = inputStr.replace(/X/g, "*")
if(!allNestsComplete(inputStr)){return "Nested operations not opened/closed properly.";}
inputStr=reduceEquation(inputStr);
inputStr = solveEquation(inputStr);
return inputStr;
};
Calculator.prototype.calcWithVars = function(inputList)
{
if(inputList.length < 2){return "One or more missing arguments!";}
var vars = [];
var assocVars = [];
var lastVarIndex = inputList.length - 2;
var i = 0;
var inputStr = inputList[inputList.length-1];
for(i=0;i<=lastVarIndex;i++)
{
vars.push(inputList[i].replace(/ /g, ""));
}
for(i=0;i<=vars.length-1;i++)
{
var vParts = vars[i].split("=");
var vName = vParts[0];
var vValue = vParts[1];
assocVars[vName] = vValue;
}
inputStr = inputStr.replace(/ /g, "");
var eqVars = inputStr.replace(/\s+/g, ' ').replace(/[^a-zA-Z-]/g, ' ').replace(/\s\s+/g, ' ');
if(inS(" ", eqVars))
{
eqVars = eqVars.split(" ");
}
else{eqVars = [eqVars];}
eqVars.sort(function(a, b){return a.length - a.length;});
var tempTokens = [];
var tempCount = 1;
for(i=0;i<eqVars.length;i++)
{
var eqVname = eqVars[i];
var substitution = arrayValueOrToken(assocVars, eqVname, "<unknown>");
if(substitution != "<unknown>")
{
inputStr = inputStr.replace(eqVname,substitution);
}
else
{
var tempToken = "#______#"+tempCount+"#______#";
tempCount++;
tempTokens.push(tempToken + "?" + eqVname);
inputStr = inputStr.replace(eqVname,tempToken);
}
}
for(i=0;i<tempTokens.length;i++)
{
var tokenSet = tempTokens[i];
var tokenParts = tokenSet.split("?");
var token = tokenParts[0];
var variableName = tokenParts[1];
inputStr = inputStr.replace(token,variableName);
}
var answerName = "<unknown>";
var eq = inputStr;
if(inS("=", inputStr))
{
var eqParts = inputStr.split("=");
answerName = eqParts[0];
eq = eqParts[1];
}
eq = this.calc(eq);
var result = [];
for(i=0;i<eqVars.length;i++)
{
var v = arrayValueOrToken(assocVars, eqVars[i], "<unknown>");
if(v != "<unknown>")
{
result.push(assocVars[eqVars[i]]);
}
}
result.push(eq);
return result;
};
function main()
{
var calculator = new Calculator();
elUserInput = document.getElementById('userinput');
console.log("input: "+ elUserInput.value);
elResult = document.getElementById('result');
equation = elUserInput.value;
result = calculator.calc(equation);
console.log("result: "+ result);
elResult.innerHTML = result;
}
</script>
</body>
</html>

Measuring the length of an array, not characters in JavaScript

I have one problem regarding the length function. The problem is that when more than one entries come in the variable, it calculates the length perfectly but for a single entry, it starts to measure the number of characters instead of the amount of elements in the array. I want the alert to show 1 because there is one entry: finance consultant, but it's showing 18.
var win = Titanium.UI.createWindow({ backgroundColor:'#FFF' });
var tableView1=Titanium.UI.createTableView();
var Row = [];
Titanium.Yahoo.yql(
'select * from html where url="http://..." '
+ 'and xpath="//tbody/tr/td/a/font" limit 25',
function(e) {
results = e.data.font;
results = results.content;
alert(results.length);
for (var i = 0; i < results.length; i++) {
var rss = results[i];
var rssRow = Titanium.UI.createTableViewRow({ ... });
var titleLabel = Titanium.UI.createLabel({ ... });
rssRow.add(titleLabel);
Row.push(rssRow);
};
tableView1.setData(Row);
});
win.add(tableView1);
win.open();

You can try the following.
results = results.content;
if (typeof results === 'string')
results = [results];
alert(results.length);
So now you've forced a result that is a string to be an array of one string. The rest of your code should work unmodified.

In the line of slashingweapon answer, but simplified, why don't you just do this:
var length = 0;
if(typeof results === "string") {
length = 1;
} else {
length = results.length;
}
alert(length);
It's simpler and cleaner.