I've written the functions below as part of a much larger application for processing FASTA formatted files via a web interface. For some reason it decided to run into infinity when call upon my baseCounts() function from within makePretty(). It might be worth noting that both functions are encapsulated by the same parent function.
The function baseCounts() returns valid data in the form of a 100+ long array, console.log confirms that it is not to blame so the problem has to be with makePretty().
Any help is welcome.
function baseCount(records){
// Count instances of Bases in array
var basecounts = Array();
for (i=0; i < records.length; i++){
var record = records[i];
console.log(record);
var count = [record.match(/A/g), record.match(/T/g), record.match(/C/g), record.match(/G/g)];
var basecount = Array();
for (i=0; i < count.length; i++){
basecount.push(count[i].length);
}
// return array of occurance
basecounts.push(basecount);
}
}
function makePretty(fasta){
// Make FASTA more human friendly
var data = Array();
var basecounts = Array();
var bases = Array();
console.log(fasta.length);
// Generate base array
for (i=1; i < fasta.length; i++){
bases.push(fasta[i][2])
}
basecounts = baseCount(bases); // RUNS INTO INFINITY
for (i=0; i < fasta.length; i++){
var record = Array();
record.push(i); // Add protein number
record.push(fasta[i][0]); // Add NC_#
record.push(fasta[i][1]); // Add base index
_record = fasta[i][2];
var l_record = _fasta.length; // Protein length
//var basecount = baseCount(_record);
var cg_content;
}
}
Your nested loops are using the same variable i, and clobbering each other's state.
for (i=0; i < records.length; i++){
...
for (i=0; i < count.length; i++){
...
}
Use distinct variables, say i and j or better yet pick meaningful names.
Also you should declare the variables (var i) to ensure they're local to the function.
Finally, use ++i, not i++. The former means "increment i" while the latter means "i, and oh by the way increment it". They both increment i, but the latter one returns the old value, which is a special language feature to use in special cases.
You're reseting your variable counter in your inner loop (i).
To avoid this, and future problems like it as well as hoisting issues, I would suggest using the newer functions such as forEach or map. You can also clean up your code this way:
function baseCountFunc(records){
// Count instances of Bases in array
var basecount = [];
records.forEach(function(record) {
var count = [record.match(/A/g), record.match(/T/g), record.match(/C/g), record.match(/G/g)];
count.forEach(function(countElement) {
basecount.push(countElement.length);
});
basecounts.push(basecount);
});
}
Also, I noticed you named your function the same name as your variables, you should avoid that as well.
Related
Question: Develop an array of 1000 objects (having properties name and number as shown).
We need a function to convert every object so the name is uppercased
and values are 5 times the original and store into the higher
variable. Similarly, another function that converts every object so
the name is lower case and value is 3 times the original, store this
into the little variable.
We need a function that takes each object in higher and finds all
objects in little that evenly divide into it. Example: 30 in
higher object is evenly divided by 6 in little.
The output of 2 must be an array of higher numbers, and in every
object there should be got (which is a variable inside the object) which will contain every little
object that evenly divided the higher.
My code:
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<script>
var n = 1000;
var sample = [];
for (var i = 0; i < n; i++) sample.push({
name:'John' + i,
value: i
});
console.log(sample);
function Converter() {
var n = 1000;
var higher = sample;
for (var i = 0; i < n; i++) higher.name = 'John' + i;
higher.value = i * 5;
console.log(higher);
}
</script>
</body>
</html>
The array of objects is created and it is as expected/required by the question, however, the converter function for higher does not work, also how should the 3rd question be done?
Some thoughts:
1) only constructors should start with a capital letter, functions should be camelcase by convention so it should be converter
2) you don't call converter() so it never gets executed
3) make sure to indent your code properly var n and var sample should be at the same depth.
4) if you omit the brackets after an if or for, only the following statement gets inside the branch, so in your case you do:
for (var i = 0; i < n; i++)
higher.name = 'John'+i;
higher.value = i*5;
so the second line isn't even executed in the loop, you want:
for (var i = 0; i < n; i++) {
higher.name = 'John'+i;
higher.value = i*5;
}
5) higher.name makes little sense as higher is an array, you want to change the name of the ith higher number which you can do with higher[i].name
6) "John1" is not in caps, you want to call toUpperCase on it (("John1").toUpperCase())
also how should the 3rd question be done?
I guess fixing your code and doing the second question is enough for today.
You could continue reading:
Coding style matters
js array iterations
You should also try to think in a more structured manner about your code here. I would suggest writing separate functions for each problem and giving them meaningful names. Perhaps something like the following:
var n = 1000;
var sample = [];
for (var i = 0; i < n; i++) sample.push({
name: 'John' + i,
value: i
});
console.log(sample);
var higher = convertToHigher(sample);
var little = convertToLittle(sample);
var higherWithDivisors = findAllDivisors(higher, little);
function convertToHigher(arr) {
var newArr = [];
// TODO: iterate through each entry in arr, create a new modified object
// with a higher value and add it to newArr
return newArr;
}
function convertToLittle(arr) {
var newArr = [];
// TODO: iterate through each entry in arr, create a new modified object
// with a lower value and add it to newArr
return newArr;
}
function findAllDivisors(arr1, arr2) {
var newArr = [];
// TODO: solve problem 3 here
return newArr;
}
So, i'm looping through the document body searching for all "#result>tbody>tr" objects. I'm then trying to search within those elements to see if any of the names exist, if they do, I would like to delete them. I got it working if I don't loop through the names and use a single object. If I try and loop through the names, it only loops four times and then nothing else happens.
Any ideas?
Edit: Currently there are 30 objects the first loop loops through. When I add the second loop into the mix to see if the sub-objects exist, it will only loop through four and than break the loop. Hope that explains better.
Example: https://jsfiddle.net/8c9p7bp5/1/
var dlList = document.querySelectorAll("#result>tbody>tr");
for (var i = 0, len = dlList.length; i < len; i++) {
var names = ['Test', 'Router', 'IP', 'Mod'];
for (var j = 0, len = names.length; j < len; j++) {
var vi = dlList[i].querySelector("td>br>img[title^='" + names[i] + "']");
if(!dlList[i].contains(vi)) {
//dlList[i].remove();
console.log(dlList[i]);
}
}
}
First mistake of your code that you are using same limit for you nested loop "len", in the first iteration the value becomes 4 that's why it will break the parent loop.
You initialize j but never use it in the inner loop.
Try this instead:
var vi = dlList[i].querySelector("td>br>img[title^='" + names[j] + "']");
Also, you should use a different variable than len for the inner loop to avoid running into variable scope issues.
I'm working in Google apps script and seem to have screwed up one of my for loops. I'm sure that I am missing something trivial here, but I can't seem to spot it.
Code Snippet:
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheets = ss.getSheets();
var lastRow = sheets[3].getLastRow();
var zw = sheets[3].getRange(2, 1, lastRow - 1, 26).getValues();
for (var j = 0; j < zw.length; ++j) {
if (zw[j][9] === 'Yes') {
var masterEmail = [];
var firstLetterLastName = [];
var first2Letter = [];
var masterEmail.push(zw[j][22]);
var firstLetterLastName.push(zw[j][1].charAt(0).toLowerCase());
var first2Letter.push(zw[j][1].charAt(0).toLowerCase() + zw[j][1].charAt(1).toLowerCase());
//The rest of the function follows...
}
}
What's Not Working:
The for loop doesn't increment. When running the code in a debugger, var j stays at a value of 0.0, and the rest of the function only runs based of off the values in the 0 position of zw.
What I need it to do (AKA - How I thought I had written it:)
The ZW variable is holding a 2 dimensional array of cell values from a Google sheet. I'm looping through that, checking the 9th value of each array entry for a string of "Yes" and then running the rest of the function (for each column with a "Yes") if the condition is true.
I thought I had this working before, but recently had to restructure and optimize some things. Now I'm starting to think I may need to rethink things and use a different loop method. Can anyone educate me?
Edit: Here's a bit more context as requested:
function menuItem1() {
var ui = SpreadsheetApp.getUi();
var response = ui.alert('Are you sure you want to send emails?', ui.ButtonSet.YES_NO);
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheets = ss.getSheets();
var lastRow = sheets[3].getLastRow();
var zw = sheets[3].getRange(2, 1, lastRow - 1, 26).getValues();
if (response === ui.Button.YES) {
for (var j = 0; j < zw.length; j++) {
if (zw[j][9] === 'Yes') {
var firstLetterLastName = [];
firstLetterLastName.push(zw[j][1].charAt(0).toLowerCase());
//Other Stuff....
}
}
}
}
I have a menu item attached to a simple onOpen, that calls menuItem1(). Calling the function prompts the user with a warning that they are about to send emails, then goes about getting data to assign email addresses based on the contents of the sheets. firstLetterLastName is an example.
I'm still not getting the loop to function, is it because I have it between two if statements? (Here is a link to the sheet)
Indeed it is quite trivial. You have mixed up your increment. You wrote
for (var j = 0; j < zw.length; ++j)
which means that you do 1 + i (and we know that at the start i = 0 which means your value will always be 1) instead of using the usual
for (var j = 0; j < zw.length; j++)
which would mean that you do i + 1 and update i, so you will get the expected 0 + 1 1 + 1 etc
EDIT:
First, I recommend instead of something like
if (responseMir === ui.Button.YES) {
// Your For loop
doing
if (responseMir !== ui.Button.YES) {
return
}
and in a similar fashion in the for loop
if (zw[j][9] !== 'Yes') {
break
}
It mostly helps increase readability by not including large blocks of code under a single if, when all you want to do is to stop execution.
Your for loop gets broken because of the mistake here:
teacherEmailMir.push(selValsMir[j][7]);
So your loop will go over once. However on the next itteration, you try to push selValsMir[1][7] which does not exist. Note that each itteration you have var selValsMir = []; inside the loop, which means that for every j selValsMir will always be an empty array. So with the following line
selValsMir.push([zw[j][0], zw[j][1], zw[j][2], zw[j][3], zw[j][4], zw[j][5], zw[j][7], zw[j][22], zw[j][23], zw[j][24]]);
your array will always have selValsMir.lenght = 1 and selValsMir[0].length = 10. So obviously trying to access anything from selValsMir[1] will throw you an error and stop the script right there.
I also recommend looking over the if statements that look at the first and first 2 letters of the name as I believe you can accomplish the same with less code. Always try to streamline. Consider using switch() where you end up using a lot of else if
I understand how to go about tasks using loops, recursion is kind of a mystery to me, but from what I understand in certain cases it can save a ton of time if looping through a lot of data.
I created the following function to loop through a large(ish) data set.
var quotes = require('./quotes.js');
//Pulls in the exported function from quotes.js
var exportedQuotes = quotes.allQuotes();
var allAuthors = exportedQuotes.author;
//Create an empty key value object, we use these to coerce unique values to an array
var uniqs = {};
//I create this object to hold all the authors and their quotes
var fullQuote = {};
//Create an object with only unique authors
for(var i = 0; i < allAuthors.length ; i++){
fullQuote[allAuthors[i]] = null;
}
//Coerce unique authors from javascript object into an array
var uniqAuthors = Object.keys(uniqs);
var quoteCount = exportedQuotes.author.length;
var iterativeSolution = function(){
for(var i = 0; i < Object.keys(fullQuote).length; i++){
for(var j = 0; j < exportedQuotes.author.length; j++){
//If the author in the unique list is equal to the author in the duplicate list
if(Object.keys(fullQuote)[i] == exportedQuotes.author[j]){
//if an author has not had a quote attributed to its name
if(fullQuote[exportedQuotes.author[j]] == null){
//assign the author an array with the current quote at the 0 index
fullQuote[exportedQuotes.author[j]] = [exportedQuotes.quote[j]]
} else {
//if an author already has a quote assigned to its name then just add the current quote to the authors quote list
fullQuote[exportedQuotes.author[j]].push(exportedQuotes.quote[j])
}
}
}
}
}
I don't currently have the skills to do analyze this, but, I'm wondering if there is a case for recursion to save the time it takes to get through all the loops. And if there is a case for recursion what does it look like for nested loops in javascript, specifically when creating key value objects recursively?
There may be a slight misunderstanding about what recursion is: recursion does not save time. It's just a different way of doing the same traversal. It generally a little easier to read, and depending on the problem, will map to certain algorithms better. However, one of the first things we do when we need to start optimizing code for speed is to remove recursion, turning them back into loops, and then even "unrolling" loops, making code much uglier, but fast, in the process. Recursion vs plain loops is almost always a matter of taste. One looks nicer, but that's hardly the only quality we should judge code on.
And also: just because it sounds like I'm advocating against using it, doesn't mean you shouldn't just try it: take that code, put it in a new file, rewrite that file so that it uses recursion. Doing so lets you compare your code. Which one is faster? Which is easier to read? Now you know something about how (your) code behaves, and you'll have learned something valuable.
Also don't sell yourself short: if you wrote this code, you know how it works, so you know how to analyze it enough to rewrite it.
Algorithms makes code fast or slow, not recursion. Some quite fast algorithms can use recursion, but that's a whole different story. Many algorithms can be written as both with recursion, and without recursion.
However, your code has a big problem. Notice how many times you call this code?
Object.keys(fullQuote)
You are re-computing the value of that many many times in your code. Don't do that. Just call it once and store in a variable, like the following:
var uniqAuthors = Object.keys(uniqs);
var uniqFullQuote = Object.keys(fullQuote);
var quoteCount = exportedQuotes.author.length;
//Loop through all quotes and assign all quotes to a unique author::Each author has many quotes
for(var i = 0; i < uniqFullQuote.length; i++){
for(var j = 0; j < exportedQuotes.author.length; j++){
//If the author in the unique list is equal to the author in the duplicate list
if(uniqFullQuote[i] == exportedQuotes.author[j]){
//if an author has not had a quote attributed to its name
if(fullQuote[exportedQuotes.author[j]] == null){
//assign the author an array with the current quote at the 0 index
fullQuote[exportedQuotes.author[j]] = [exportedQuotes.quote[j]]
} else {
//if an author already has a quote assigned to its name then just add the current quote to the authors quote list
fullQuote[exportedQuotes.author[j]].push(exportedQuotes.quote[j])
}
}
}
}
You don't have to iterate Object.keys(fullQuote).
var quotes = require('./quotes.js'),
exportedQuotes = quotes.allQuotes(),
allAuthors = exportedQuotes.author,
fullQuote = Object.create(null);
for(var i=0; i < allAuthors.length; ++i)
(fullQuote[allAuthors[i]] = fullQuote[allAuthors[i]] || [])
.push(exportedQuotes.quote[i])
I don't recommend recursion. It won't improve the asymptotic cost, and in JS calling functions is a bit expensive.
I got really curious and created a recursive solution just to see how it works. Then timed it, my iterative solution took 53 seconds to run, while my recursive solution took 1 millisecond to run. The iterative approach can obviously be tweaked based on the answers provided below, to run faster, but a recursive approach forced me to think in a "leaner" manner when creating my function.
var exportedQuotes = quotes.allQuotes();
var allAuthors = exportedQuotes.author;
var n = allAuthors.length
var fullQuote = {};
var recursiveSolution = function(arrayLength) {
//base case
if(arrayLength <= 1){
if(fullQuote[exportedQuotes.author[0]] == null){
fullQuote[exportedQuotes.author[0]] = [exportedQuotes.quote[0]];
}else{
fullQuote[exportedQuotes.author[0]].push(exportedQuotes.quote[0])
}
return;
};
//recursive step
if(fullQuote[exportedQuotes.author[arrayLength]] == null){
fullQuote[exportedQuotes.author[arrayLength]] = [exportedQuotes.quote[arrayLength]];
}else{
fullQuote[exportedQuotes.author[arrayLength]].push(exportedQuotes.quote[arrayLength])
}
newLength = arrayLength - 1;
return recursiveSolution(newLength);
}
////////Timing functions
var timeIteration = function(){
console.time(iterativeSolution);
iterativeSolution(); // run whatever needs to be timed in between the statements
return console.timeEnd(iterativeSolution);
}
var timeRecursive = function(){
console.time(recursiveSolution(n));
recursiveSolution(n); // run whatever needs to be timed in between the statements
return console.timeEnd(recursiveSolution(n));
}
So I'm working on this script. When I'm done with it, it should be used for making 2-and-2 groups. But anyway; The 'input' array in the start of the script, will get 22 different inputs from my HTML file. As a standard, I gave them the values 1-22. The thing is my two blocks '1st number' and '2nd number' doesn't work very well: they don't return the right numbers. Cause I want every elev[x] to be used once! Not 2 times, not 0 times, once! And the blocks returns like some of them twice and some of them isn't even used. So how can I fix this?
function Calculate(){
var elev = [];
var inputs = document.getElementsByName("txt");
for(i=0; i<inputs.length; i++) {
elev[i] = {
"Value": inputs[i].value,
"Used": false
};
}
function shuffle(elev){
var len = elev.length;
for(i=1; i<len; i++){
j = ~~(Math.random()*(i+1));
var temp = elev[i];
arr[i] = elev[j];
arr[j] = temp;
}
}
for(var v=0; v<1; v++) {
shuffle(elev);
document.write(elev + '<br/>\n');
}}
Yes, I'm still new at programming and I just wanna learn what I can learn.
Problem solved by doing the Fisher-Yates shuffle.
The idea of shuffling an array and iterating over it is correct, however, sorting by a coin-flipping comparator (a common mis-implementation; suggested by the other answer) is not the correct way to shuffle an array; it produces very skewed results and is not even guaranteed to finish.
Unless you're willing to fetch underscore.js (arr = _.shuffle(arr)), It is recommended to use the Fisher-Yates shuffle:
function shuffle(arr){
var len = arr.length;
for(var i=1; i<len; i++){
var j = ~~(Math.random()*(i+1)); // ~~ = cast to integer
var temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
...
shuffle(elev);
for(var i=0; i<elev.length; i++){
//do something with elev[i]
console.log(elev[i].Value);
}
also, note that object fields should be lowercase, not uppercase (value', not 'Value'). Also, theUsed` field should not be neccessary since you now iterate in order. Also, any chance you could use an array of Values? They seem to be the only field in your objects.
Also, Don't use document.write(). It doesn't work as expected when used after the page load. If you want to append something to the document, you hate jQuery and other frameworks and you don't want to go the long way of creating and composing DOM nodes, document.body.innerHTML += is still better than document.write() (but still consider appending DocumentFragments instead').
demo: http://jsfiddle.net/honnza/2GSDd/1/
You are only getting random numbers once, and then processing them if they haven't already been used.
I would suggest shuffling the array (elev.sort(function() {return Math.random()-0.5})) and then just iterating through the result without further random numbers.