I want to print out all number from 1 to 1,000,000 with 1,000 numbers per line. and return the response without having a long delay.
Thanks in advance for any type of help!!!
Well, first you can create a function to print numbers from 1 to 1000.
function getThousand(index) {
var result = '';
for (var i = index; i < index + 1000; i++) {
result += i + ' ';
}
return result;
}
Then, you need a function to call this for 1 to 1000000.
function getAll() {
var result = '';
for (var i = 0; i < 1000; i++) {
result = getThousand((i * 1000) + 1) + " \n";
fs.appendFileSync('foo.txt', result);
}
}
Then call it all:
getAll();
This will save your lines into a file. At the end of getAll() you can print what you need.
Related
I am new to Google Sheet scripting.
I am writing a code to strip the sixth components from a long text that is based on a naming convention. The text have 6 parts all separated by an underscore. However, my code is not returning anything
function RetailerStrip(account) {
var count = 0;
var retname = "";
var retcount = 0;
for(var i = 0, len = account.length; i < len; i++) {
if (account[i] =="_") {
++count;
}
if (count == 5) {
retname[retcount]= account[i];
++retcount;
}
}
return retname;
}
I then call this function from sheet as below
=RetailerStrip("abc_def_ghi_jkl_mno_pqr")
When I tried to declare 'retname' as an array the function did return the required text (fifth component) but the text was spread across multiple cells with on character in each cell, and not as a single string in one cell
var retname = [];
Please help
You could try this:
function RetailerStrip(str) { return str.split('_')[5]; }
The split() method creates an array.
But if you prefer to stick with the string-iteration method, you could use this:
function RetailerStrip(account) {
var count = 0;
var retname = []; // Array
var retcount = 0;
for (var i = 0, len = account.length; i < len; i++) {
if (account[i] =="_") {
++count;
}
if (count == 4) {
retname[retcount]= account[i];
++retcount;
}
}
retname.shift(); // To get rid of the underscore from the array
var retnameString = retname.join(''); // To convert the array to a string
return retnameString;
}
When I remove Thread pooling or uncomment Console.WriteLine() from code then code works fine, but to improve performance I want to process each DataTable column on separate Task. It throws index out of range exception.
DataTable dt = new DataTable();
private async void btnExcel_Click(object sender, RoutedEventArgs e)
{
dt = new DataTable("worksheet");
dt.Columns.Add("Id");
dt.Columns.Add("MobileNo");
dt.Columns.Add("Name");
dt.Columns.Add("Name1");
dt.Columns.Add("Name2");
dt.Columns.Add("Name3");
dt.Columns.Add("Name4");
for (int i = 0; i < 100; i++)
dt.Rows.Add(i, "99999", "ABC" + i, "n1", "n2", "n3", "n4");
//var tasksInFlight = new Task[dt.Columns.Count];
var tasksInFlight = new List<Task>();
for (int index = 0; index < dt.Columns.Count; index++)
{
tasksInFlight.Add(updateDt(index, "col " + index));
}
//await Task.Factory.ContinueWhenAll(tasksInFlight, cT => { string a = "abc"; });
await Task.WhenAll(tasksInFlight);
}
public async Task updateDt(int colNum, string data)
{
try
{
Task t = Task.Run(() =>
{
for (int i = 0; i < dt.Rows.Count; i++)
{
// Console.WriteLine("Col Num : " + colNum + " i = " + i);
dt.Rows[i][colNum] = data;
}
});
await t;
}
catch (Exception ex)
{
}
}
When you call tasksInFlight.Add(updateDt(index, "col " + index)); the value of index is not read; you merely store a task that will be executed later - when you call Task.WhenAll. It is when the tasks are executed when the value of index is evaluated. Which happens after the loop is over and the value of index is now equal to dt.Columns.Count, which is out of the range of the array.
Read about C# closures here.
To fix it, you can do like this:
for (int index = 0; index < dt.Columns.Count; index++)
{
int tmpIndex = index;
tasksInFlight.Add(updateDt(tmpIndex, "col " + tmpIndex));
}
EDIT: After further investigation it turns out that DataTable is not thread-safe.
In addition to the fix above, DataTable should be accessed in a lock:
lock (dt)
{
dt.Rows[i][colNum] = data;
}
However, unless retrieving the actual data to put in the DataTable CPU-intensive, the lock eliminates all benefits of concurrency in this case.
I was writing a JavaScript implementation of merge sort in NodeJS, since the native V8 sort function uses quick sort, which is less efficient than merge sort in its worst case. In order to the test the performance, I made an array of 10000 elements, pre-sorted (worst-case for quick sort) and timed how long it took to sort this list with both functions. In a single execution, the native sort function takes about 16 milliseconds, where my implementation takes about 9 milliseconds. However, when executing both 100 times, the native sort takes about 2.1 milliseconds on average, and mine takes about 4.3 milliseconds. Here is my code:
const { performance } = require('perf_hooks');
function merge(a, b, func) {
const array = new Array(a.length + b.length);
let aIndex = 0;
let bIndex = 0;
while(aIndex + bIndex < array.length) {
if(aIndex >= a.length || func(a[aIndex], b[bIndex]) > 0) {
array[aIndex + bIndex] = b[bIndex++];
} else {
array[aIndex + bIndex] = a[aIndex++];
}
}
return array;
}
function mergeSort(list, func) {
if(list.length <= 1) {
return list;
}
const half = list.length / 2;
return merge(mergeSort(list.slice(0, half), func), mergeSort(list.slice(half), func), func);
}
function time(func, iters) {
let sum = 0;
for(let i = 0; i < iters; i++) {
let startTime = performance.now();
func();
sum += performance.now() - startTime;
}
return sum / iters;
}
const arr = [...Array(10000).keys()];
const sortFunc = (a, b) => a - b;
console.log("JavaScript built-in sort execution time, one iteration:")
console.log(time(() => arr.sort(sortFunc), 1)); // ~16
console.log("Manually implemented merge sort execution time, one iteration:")
console.log(time(() => mergeSort(arr, sortFunc), 1)); // ~9
console.log();
console.log("JavaScript built-in sort average execution time, 100 iterations:")
console.log(time(() => arr.sort(sortFunc), 100)); // ~2.1
console.log("Manually implemented merge sort average execution time, 100 iterations:")
console.log(time(() => mergeSort(arr, sortFunc), 100)); // ~4.3
Why is it so much faster when executed repeatedly than only once, and why is this improvement more pronounced for the native sort function?
EDIT: I was able to make my algorithm more efficient by tracking array indices instead of using the slice method. My code now consistently beats v8's native sort when used on pre-sorted arrays, but loses on randomized arrays, as expected. Here is that code, for those interested:
const { performance } = require('perf_hooks');
function merge(a, b, func) {
const array = new Array(a.length + b.length);
let aIndex = 0;
let bIndex = 0;
while(aIndex + bIndex < array.length) {
if(aIndex >= a.length || func(a[aIndex], b[bIndex]) > 0) {
array[aIndex + bIndex] = b[bIndex++];
} else {
array[aIndex + bIndex] = a[aIndex++];
}
}
return array;
}
function mergeSortRec(list, func, start, limit) {
if (limit === 1) {
return [list[start]];
}
const half = limit / 2 | 0;
return merge(mergeSortRec(list, func, start, half), mergeSortRec(list, func, half + start, limit - half), func);
}
function mergeSort(list, func) {
return mergeSortRec(list, func, 0, list.length);
}
function time(func) {
let startTime = performance.now();
func();
return performance.now() - startTime;
}
const sortFunc = (a, b) => a - b;
console.log();
console.log("--- Sequential array ---");
console.log();
const sequenceArr = [...Array(10000).keys()];
console.log("JavaScript built-in sort execution time, one iteration:");
console.log(time(() => sequenceArr.slice(0).sort(sortFunc)));
console.log("Manually implemented merge sort execution time, one iteration:");
console.log(time(() => mergeSort(sequenceArr, sortFunc)));
let sum = 0;
for(let i = 0; i < 100; i++) {
const array = sequenceArr.slice(0);
sum += time(() => array.sort(sortFunc));
}
console.log("JavaScript built-in sort average execution time, 100 iterations:");
console.log(sum / 100);
sum = 0;
for(let i = 0; i < 100; i++) {
sum += time(() => mergeSort(sequenceArr, sortFunc))
}
console.log("Manually implemented merge sort average execution time, 100 iterations:");
console.log(sum / 100);
console.log();
console.log("--- Randomized array ---");
console.log();
const randomArrays = new Array(101);
for(let i = 0; i < 101; i++) {
randomArrays[i] = new Array(10000);
for(let j = 0; j < 10000; j++) {
randomArrays[i][j] = Math.random() * 5000 | 0;
}
}
console.log("JavaScript built-in sort execution time, one iteration:");
console.log(time(() => randomArrays[100].slice(0).sort(sortFunc)));
console.log("Manually implemented merge sort execution time, one iteration:");
console.log(time(() => mergeSort(randomArrays[100], sortFunc)));
sum = 0;
for(let i = 0; i < 100; i++) {
const array = randomArrays[i].slice(0)
sum += time(() => array.sort(sortFunc));
}
console.log("JavaScript built-in sort average execution time, 100 iterations:");
console.log(sum / 100);
sum = 0;
for(let i = 0; i < 100; i++) {
sum += time(() => mergeSort(randomArrays[i], sortFunc))
}
console.log("Manually implemented merge sort average execution time, 100 iterations:");
console.log(sum / 100);
I need to do a loop in Node JS where I need the result of the previous iteration.
function jsonParser(txt_file, cb) {
var perc = 0;
lines = txt_file.split('\n');
insert_communication = 'INSERT INTO communication (account_id, contact_id, type_com_id, coin_id, com_datetime, ' +
'destination_key, destination_st, duration, cost, description, discount) VALUES ';
insert_internet = 'INSERT INTO internet_data (account_id, contact_id, type_com_id, coin_id, com_datetime, ' +
'duration, cost, description, discount) VALUES ';
for (let i = 2; i < lines.length; i++) {
readTextFile2(lines[i], function (cb) {
if (cb[0] == "communication")
insert_communication += cb[1] + ',';
if (cb[0] == "internet")
insert_internet += cb[1] + ',';
});
}
cb(insert_communication);
}
How I am supposed to achieve this?
Thanks
for (let i = 2; i < lines.length; i++) {
const previous = lines[i - 1 ];
const hasPrevious = !!previous;
if(hasPrevious) {
//ok you have a previously value, now you could use it
}
readTextFile2(lines[i], function (cb) {
if (cb[0] == "communication")
insert_communication += cb[1] + ',';
if (cb[0] == "internet")
insert_internet += cb[1] + ',';
});
}
ok, I have a homework assignment where I have to read in files and calculate the distance between a bunch of numbers in the files and then print out the mean and standard deviation of each set of numbers. The end of the script, where the console.log stuff is, is giving all NaN for the variables. Can anyone help me out?
*I've omitted repeating parts of the script to make it shorter (their are more arrays than just the lHipJoint array and the calculations for them but I left them out).
var fs = require('fs');
var lHipJoint = new Array();
//open the first text file
fs.readFile('file.txt','utf8', function (err, data)
{
if (err) throw err;
//split the data into an array with each line as an element
stuff=data.split('\n');
for (var i = 0; i < stuff.length; i++)
{
//function that processes each line into an array
//with each number as an element and does the euclidean dis.
processLine(stuff[i]);
}
data.length = 0;
stuff.length = 0;
});
//do the same for the next file
fs.readFile('file2.txt','utf8', function (err, data)
{
if (err) throw err;
stuff=data.split('\n');
for (var i = 0; i < stuff.length; i++)
{
processLine(stuff[i]);
}
data.length = 0;
stuff.length = 0;
});
//and again
fs.readFile('file3.txt','utf8', function (err, data)
{
if (err) throw err;
stuff=data.split('\n');
for (var i = 0; i < stuff.length; i++)
{
processLine(stuff[i]);
}
data.length = 0;
stuff.length = 0;
});
//and again
fs.readFile('file4.txt','utf8', function (err, data)
{
if (err) throw err;
stuff=data.split('\n');
for (var i = 0; i < stuff.length; i++)
{
processLine(stuff[i]);
}
data.length = 0;
stuff.length = 0;
});
//and again
fs.readFile('file5.txt','utf8', function (err, data)
{
if (err) throw err;
stuff=data.split('\n');
for (var i = 0; i < stuff.length; i++)
{
processLine(stuff[i]);
}
data.length = 0;
stuff.length = 0;
});
//and again
fs.readFile('file6.txt','utf8', function (err, data)
{
if (err) throw err;
stuff=data.split('\n');
for (var i = 0; i < stuff.length; i++)
{
processLine(stuff[i]);
}
data.length = 0;
stuff.length = 0;
});
//function to split each line into an array with each number as an element
//then parse the number strings into floats and do the euclidean distances,
//storing the values in arrays for each bone.
function processLine(line)
{
var line1 = line
var numbers = line1.split(" ");
line1.length = 0;
for (var i = 0; i < numbers.length; i++)
{
var number = parseFloat(numbers[i]);
line1[i] = number[i];
}
lHipJoint = Math.sqrt((line1[6] - line1[9])*(line1[6] - line1[9]) + (line1[7] - line1[10])*(line1[7] - line1[10]) + (line1[8] - line1[11])*(line1[8] - line1[11]));
//reset the arrays so they can be reused
line1.length = 0;
numbers.length = 0;
number.length = 0;
}
//calculations and output for the mean and SD of each bone's distance from the root bone.
for(var i = 0; i < lHipJoint.length; i++)
{
var lHipJointTotal = lHipJointTotal + lHipJoint[i];
}
var lHipJointMean = lHipJointTotal/lHipJoint.length;
for(var i = 0; i < lHipJoint.length; i++)
{
var lHipJointSDSum = lHipJointSDSum + (lHipJoint[i] - lHipJointMean)*(lHipJoint[i] - lHipJointMean);
}
var lHipJointSD = Math.sqrt(lHipJointSDSum/lHipJoint.length);
console.log("The mean distance of the left hip joint from the root bone is " +lHipJointMean+ " and the standard deviation is " +lHipJointSD+ ".\n");
You are doing a lot of strange things here in your script i will try to
bring upp as manny as i can.
So first of all dont reset arrays.
your in a garbage collected language just reallocate new ones.
Also in the processLine function you are assigning numbers to the indexes of a string
i asume you think its an array but its not the same thing.
strings are immutable (cant be changed) in javascript.
In the aggregating for loops att the bottom of the file you are
declaring the variable in every iteration. you want to declare it before the loop like this.
var x = 0;
for(var i = 0; i < list.length; i++) {
x = x + ......
}
Your cals to read the files all do the same thing.
So you want to use the same function for that.
write it ones.
You are assigning to the lHipJoint array in the
processLine function my understanding is that you want to add
the calculated value to the array.
You can do this with the push method like this
lHipJoint.push(Math.sqr(........
Also theres a problem with using the async file reading
sins your printing the result before you even read the files.
if you want to use the async ones you need to coordinate so that.
you only print the result when you done all the file reading.
but a tips is to use the non async ones in this case.
I understand this is an assignment so you might not want to read my
attempt to correct the program beneath.
Maybe read it after you handed in yours, but im leaving it here
for the q&a reference for others reading this.
var fs = require("fs");
var filePaths = ["file.txt", "file2.txt",
"file3.txt", "file4.txt",
"file5.txt", "file6.txt"];
var lHipJoint = [];
filePaths.forEach(function(path) {
var content = fs.readFileSync(path, "utf-8");
var lines = content.split("\n");
lines.forEach(function(line) {
if(line.trim() === "") return;
var numbers = line.split("\t").map(parseFloat);
// im not touching your calculation :D
lHipJoint.push(Math.sqrt((numbers[6] - numbers[9])*(numbers[6] - numbers[9])
+ (numbers[7] - numbers[10])*(numbers[7] - numbers[10]) + (numbers[8] - numbers[11])
* (numbers[8] - numbers[11])));
});
});
var lHipJointTotal = lHipJoint.reduce(function(p, c) {
return p + c;
});
var lHipJointMean = lHipJointTotal / lHipJoint.length;
var lHipJointSDSum = lHipJoint.reduce(function(p, c) {
return p + (c - lHipJointMean) * (c - lHipJointMean);
}, 0);
var lHipJointSD = Math.sqrt(lHipJointSDSum/lHipJoint.length);
console.log("The mean distance of the left hip joint from the root bone is "
+ lHipJointMean + " and the standard deviation is " + lHipJointSD + ".\n");
there might be some error in this program i dont know how the data looks but i hope this helps
you.