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    Fourier transform of irregularly spaced data Ask Programming

    January 01, 2019

    Fourier transform of irregularly spaced data Ask Programming

    Fourier transform of irregularly spaced data

    Posted: 01 Jan 2019 03:44 PM PST

    I've got real world data and I want to do an fft (fast fourier transform) but there's a catch. The X values are not evenly spaced. The fourier transform I want to do has been called NUfft (non uniform fft) or irregularly spaced fourier transform.

    I have tried NUFFT programs in matlab/octave, python, mathematica but I cannot for the life of me figure out how to input a list of data and get an output list of data.

    Example (X is time data, Y is physical measurement data, list is N = 6 elements long):

    X Y

    1.3 6.1

    1.5 7.2

    2.0 4.9

    2.1 3.0

    2.3 2.9

    2.5 1.9

    ​

    Wise programmers of reddit, please guide me to an easy non uniform fft of my data.

    submitted by /u/pigeon181
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    6-digit password guessing (JS?) app questions

    Posted: 01 Jan 2019 08:37 PM PST

    Hello r/AskProgramming!

    I am a primary school teacher in desperate need of help. A coworker of mine has called on a favor and I need to help him create a password guessing game of sorts. What we would like to do is put an app (I'm assuming I could write this in JS) that is on an interactive white board that has a simple interface with a 4-6 digit password that can be typed in and guessed. We think the best way would be to have the teacher be able to write the password the same way you would on a computer or phone without being able to see the characters being written. Then onces it is set, students cant come up to the board and press on drop boxes with numbers 0-9 and try to guess the password. It's probably better if they can guess the 6 numbers all at once and then press a button and then see red or green lights if each number was guessed correctly or not. The interface can be simple as long as that it is clean. My coworker said that he will have it up in class and parents may see it.

    I am not looking for someone to straight up do this for me, as I wouldn't mind using this as a learning experience for myself and my class. What I need rather, is for someone to point me in the right direction with some instructions if that's possible. However if someone wanted to do it AND provide instructions I would obviously be happy with that as well, but that's asking too much. I have some experience coding in JS and Python, so either is fine, however I have never used Python outside of an online IDE. My coworker will use it in class, but I will try and walk my year 4-5 students through it (if I can get it myself). I know how to teach the concepts in coding, however my own recently experience is... lacking.

    If someone knows of a website or an app that does what I'm looking for that would be lovely as well, however I still wouldn't mind some advise on how to start this on my own. I would give it a go without the help but I'm at a bit of a loss for time as school just got back in and I'm up to my neck in preparation for test week.

    Thank you so much for your help! (and I'm sorry for the beefy text)

    submitted by /u/damnwall
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    Using .htaccess, how can I load content from two different folders (based on the subdomain) and keep the old URLs?

    Posted: 01 Jan 2019 08:13 PM PST

    My website is example.com.

    In my public_html folder, I have two folders. One is called main, and the other is called report.

    When somebody navigates to example.com, I want to serve content from the main folder, but I want their URL to remain the same.

    So, if they navigate to example.com/file.html, I want them to see the file.html file that's in the main folder, but I don't want their URL to change to example.com/main/file.html.

    Similarly, if they navigate to report.example.com/report1.pdf, I want them to see the report1.pdf file that's in the report folder, but I don't want their URL to change to report.example.com/report/report1.pdf.

    The closest thing I've been able to achieve is this:

    DirectoryIndex index.php index.html index.htm RewriteEngine on RewriteBase / RewriteCond %{HTTP_HOST} ^example.com$ [NC] RewriteRule ^((?!main).*)$ /main/$1 RewriteCond %{HTTP_HOST} ^report.example.com$ [NC] RewriteRule ^((?!report).*)$ /report/$1 [L]

    That seems to work to some extent, but:

    • If somebody navigates to http://example.com/report/index.html, the server incorrectly loads the index.html file from the public_html/report folder rather than the public_html/main/report folder. Normally that path would make sense, but in this case I'm trying to change that behavior.

    • If somebody navigates to http://report.example.com/test, the server correctly displays the public_html/test/index.html file, but redirects them to http://report.example.com/report/test/.

    How can I load the correct files and keep the URLs correct?

    submitted by /u/Pikamander2
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    Is it possible to use Scrapy to scrape only new contents every time new post is out?

    Posted: 01 Jan 2019 07:52 PM PST

    I'm currently using Scrapy and Python to scrape a website but the website only post new contents every 2 days and I would like to scrape the new data automatically without restarting the scraper. How do I go about doing it?

    submitted by /u/PewPaw-Grams
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    Good books/articles to improve lead role

    Posted: 01 Jan 2019 07:47 AM PST

    I am looking to improve my skills as a lead developer this year and make my team more effective.

    We have minimal barriers and rarely do meetings while being a fairly small group.

    I would like to learn more about task/project planning/management as well as just general tips for people in my position.

    Any recommendations?

    submitted by /u/boxhacker
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    How to search for data in API Python

    Posted: 01 Jan 2019 07:22 PM PST

    My Python script is getting there, I just need to add a search method so the user can search for key words like the starting letters of a planet or host name, or a number to reference for mass, and then it displays the closest results. Here's what I have so far.

    import urllib.request import json menu = input("Enter sorting 'distance', 'alphabetical', 'stellar mass', or 'planet mass': ") print() length = input("Enter the amount of results you would like to receive: ") print() if menu == 'distance': sort = '&order=st_dist' elif menu == 'stellar mass': sort = '&order=st_mass' elif menu == 'planet mass': sort = '&order=pl_bmassj' else: sort = '&order=pl_hostname' base = "https://exoplanetarchive.ipac.caltech.edu/cgi-bin/nstedAPI/nph-nstedAPI?" data_table = "table=exoplanets&select=" host_name = "pl_hostname," host_mass = "st_mass," planet_name = "pl_name," planet_massj = "pl_bmassj," ra = "ra," dec = "dec," distance = "st_dist" format = "&format=json" link = urllib.request.urlopen(base + data_table + host_name + host_mass + planet_name + planet_massj + ra + dec + distance + sort + format) url = link.read() api = json.loads(url.decode("utf-8")) for item in api[:int(length)]: print("Host: %s" %(item["pl_hostname"])) print("Mass: %sM\u2609" %(item["st_mass"])) print("Planet: %s" %(item["pl_name"])) print("Mass: %sM\u1D0A" %(item["pl_bmassj"])) print("Distance from Earth: %spc" %(item["st_dist"])) print("--------------------------------")
    submitted by /u/kurotheactivist
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    Why does this solution work for an algorithm to check if a sequence is almost increasing?

    Posted: 01 Jan 2019 09:00 AM PST

    I am trying to solve a problem from CodeSignal:

    ​

    Given a sequence of integers as an array, determine whether it is possible to obtain a strictly increasing sequence by removing no more than one element from the array.

    For 

    sequence = [1, 3, 2, 1]

    the output should be

    almostIncreasingSequence(sequence) = false

    For 

    sequence = [1, 3, 2]

    the output should be

    almostIncreasingSequence(sequence) = true

    ​

    I was trying to analyze the top solution:

    ​

    boolean almostIncreasingSequence(int[] a) { int cnt = 0 , cnt2 = 0; for(int i = 0 ; i < a.length-1 ; i++){ if(a[i] >= a[i+1]) cnt++; } for(int i = 0 ; i < a.length-2 ; i++){ if(a[i] >= a[i+2]) cnt2++; } return cnt + cnt2 > 2 ? false : true; }

    I understand the first loop, comparing the current and following element. I don't understand the second loop, comparing the current element and then the next next element. Why does this work?

    submitted by /u/pablolikescats
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    memory allocation when creating directed graphs on

    Posted: 01 Jan 2019 06:35 PM PST

    what if i exploit the stack allocations that happen during recursing down a tree, figuring out the total memory required at the end of the recursion, allocating exactly that and while coming back up the recursion stack(s) do tail-calls which copy the data from the stack to its final resting place?

    the sticky point is how to allocate the exact memory required, once, while only traversing through the tree, once.

    i am sorry i am not good at explaining things like this :(

    submitted by /u/MasochistCoder
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    Help with Discord Bot?

    Posted: 01 Jan 2019 10:42 AM PST

    Hello,

    I've taken all the steps to making my own Discord Bot from this tutorial here, but my bot never came online. I must have gone through a dozen tutorials by now, trying to figure out why it won't come online. I've downloaded node.js and git. I ran the code at the bottom of the tutorial and a similar one from the bottom of another tutorial in command prompt.

    If it's of any help, someone said run node bot.js, so I did, and here's what command prompt told me.

    I'm an hvac tech, not a programmer, so code is not my forte. (Although I'd love to learn.)

    Any help is appreciated!

    Edit: I have no idea if it would work, since it won't come online, period, but apparently you can run the bot 24/7 if you run it through Heroku? I began following a tutorial for that, but the code they were using was half the size of the original code that I was given, so I didn't know if it would work. The bot.js code I'm using is the first tutorial's one and this is the Heroku one.

    submitted by /u/tunafishpaste
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    Creating an Online Purchase Bot

    Posted: 01 Jan 2019 03:45 PM PST

    I'm writing this in Java because I'm just creating a simple JFX program. Is it possible auto fill, click things on a page, or anything like that without using a browser automation tool like Selenium, but rather using HTTP requests? I wouldn't mind using Selenium, but I just don't want Selenium to open the browser which I'm pretty sure you can't avoid. I'm not asking to be given the code, I'd just like to know if this is possible and how I could go about doing it! Thanks!

    submitted by /u/cooopjc
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    Deploying smart contract onto XDC Blockchain

    Posted: 01 Jan 2019 07:45 AM PST

    I'm facing some issues trying to deploy my smart contract (written in Solidity) on the XDC Blockchain.

    I have been following this guide and while I have managed to do majority of it, I am stuck on the 4th point, i.e. "Interact with your contract".

    When I type getPartialSchwiftyInstance I get undefined for the address field. However, in my geth.log file I can see the address.

    submitted by /u/PositivePlayer1
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    JavaScript DOMS

    Posted: 01 Jan 2019 10:20 AM PST

    Can someone clarify my doubts. What does

    document.addEventListener('init',function (event){

    var page = event.target }):

    What's the above line of code suppose to do?

    If I am correct it is instructing the document object which is my webpage to listen for a particular event called initialisation?(not so sure about this)

    If the page is initiated, an anonymous function with the argument event will run (I suppose event is a global reserved variable)?

    Also what is e I often would see an anonymous function with e as argument.

    submitted by /u/UniversalZeroZeroX
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    What should an ISO C conforming compiler do when compiling non-conforming code?

    Posted: 01 Jan 2019 11:58 AM PST

    According to the standard, the compiler should tell if a program contains a illegal instruction: "If a program contains a violation of any diagnosable rule, a conforming implementation shall issue at least one diagnostic message"

    But what else does it have to do? I'm guessing that if you have an error in your source code, then the output can be whatever it likes, but I can't find it in the standard.

    submitted by /u/groenewald
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    How do you search for specific data in an API

    Posted: 01 Jan 2019 11:32 AM PST

    My script is getting there, I just need to add a search method so the user can search for key words like the starting letters of a planet or host name, or a number to reference for mass, and then it displays the closest results. Here's what I have so far.

    import urllib.request import json menu = input("Enter sorting 'distance', 'alphabetical', 'stellar mass', or 'planet mass': ") print() length = input("Enter the amount of results you would like to receive: ") print() if menu == 'distance': sort = '&order=st_dist' elif menu == 'stellar mass': sort = '&order=st_mass' elif menu == 'planet mass': sort = '&order=pl_bmassj' else: sort = '&order=pl_hostname' base = "https://exoplanetarchive.ipac.caltech.edu/cgi-bin/nstedAPI/nph-nstedAPI?" data_table = "table=exoplanets&select=" host_name = "pl_hostname," host_mass = "st_mass," planet_name = "pl_name," planet_massj = "pl_bmassj," ra = "ra," dec = "dec," distance = "st_dist" format = "&format=json" link = urllib.request.urlopen(base + data_table + host_name + host_mass + planet_name + planet_massj + ra + dec + distance + sort + format) url = link.read() api = json.loads(url.decode("utf-8")) for item in api[:int(length)]: print("Host: %s" %(item["pl_hostname"])) print("Mass: %sM\u2609" %(item["st_mass"])) print("Planet: %s" %(item["pl_name"])) print("Mass: %sM\u1D0A" %(item["pl_bmassj"])) print("Distance from Earth: %spc" %(item["st_dist"])) print("--------------------------------")
    submitted by /u/kurotheactivist
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    Fantasy Golf Project

    Posted: 01 Jan 2019 10:43 AM PST

    My dad runs a fantasy golf pool with some of his golf buddies. Each year more and more people are joining in, and he is starting to have trouble getting all of the people and their team picks into his excel files, so, he's asked me to help him automate the process.

    ​

    I want to create a website that allows for users to register, then pick their team for the upcoming tournament using a webapp that I've created. The webapp helps the user create a valid player/team, which is then put into an array. I need to be able to store each user's team array and access it when needed. I've been looking into Auth0, Okta, Passport.js, jwt tokens, etc. trying to wrap my head around authentication, sessions, etc. but I am still not quite grasping the whole flow of things. I've ran the sample project from Auth0 and have been able to create a simple page where I can login in and out, but have had trouble implementing it into my site. I tried integrating it into my netbeans project, but found that auth0 was setup on port 3000 but my netbeans project was running on port 8383. I've got mysql server setup, and have been able to run commands from cmd, and from netbeans.

    ​

    I'm a novice programmer, but I have dabbled with a bit of java, javascript, html, css, php, mysql, python, c#.. (As a kid I setup a php apache server to run counter-strike and had user stats, admin mods and customized plugins, etc, so some of this is familiar)

    tl;dr: I need to fill in some knowledge gaps on how to go from authenticating a user to allowing that user to use a webapp to create data that will be stored in their "file."

    submitted by /u/JMB1007
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    Why do most people claim that Java or C# are easier languages to start learning than C++?

    Posted: 01 Jan 2019 04:40 PM PST

    I disagree with that. I'm learning C++ at university and I think it's much more simple than Java and C#, with which I tried to make some programs.

    First of all, the syntax is much easier to grasp.

    To ask for user input, simply put std::cin >> x in C++. In Java, you must import java.util.Scanner, then make a Scanner object like this: Scanner sc = new Scanner(System.in); and then use this object like int x = sc.nextInt(); . In C# you must ask for string input and convert it to integer if you need an integer like this: int x = Convert.ToInt32(Console.ReadLine());. Why all this hassle??

    To use a dynamic list, simply write #include <vector> in C++ and then a list is created like vector<int> list;. In Java, correct me if I'm wrong, you must import java.util.List AND java.util.ArrayList. Why?? In C# you must import System.Collections.Generic... Also why???

    To make an object, simply write MyClass obj;. In Java and C# you must write MyClass obj = new MyClass();, right? Also why?...

    To make an array in C++, write e.g. int arr[SIZE]; In Java and C# it's int[] arr = new int[SIZE];... Too much writing...

    Yes, I know Java and C# are mostly object-oriented, thus this syntax, and this is exactly why I think it's too difficult for beginners to understand.

    Maybe the only thing in C++ that's difficult is pointers, I think, as well as abstract data types. But why would I need to use the latter anyway?...

    Correct me if I'm wrong since I'm relatively new to programming. So I would like to see your opinions to this. =)

    NOTE: I would like to say thank you for your responses. I didn't expect so many replies.

    Also, this thread might seem like a rant, but actually are my thoughts and I would like you to explain me where I was wrong. Some answers did that gently, some others did that in a kind of insulting way.

    I said I'm a relatively beginner programmer. And I didn't expect I would lose all my karma just by asking a question......

    submitted by /u/HiTek_142857
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    How to print data correctly from JSON API

    Posted: 31 Dec 2018 11:17 PM PST

    I want to print all of the data in blocks. I currently have this script which will print the first block of data (when I have index set to 0). I have been told I can use json.dump() and that I can also move the data into a dictionary. Considering I am learning python, please explain how I can do that. What exactly do I need to be doing with my script? What do I remove/add and where?

    import requests import json url = "https://exoplanetarchive.ipac.caltech.edu/cgi-bin/nstedAPI/nph-nstedAPI?table=exoplanets&select=pl_hostname,st_mass,pl_name,pl_bmassj,ra,dec,st_dist&order=st_dist&format=json" grab = requests.get(url) api = grab.json() index = 0 stellar_name = api[index]["pl_hostname"] stellar_mass = api[index]["st_mass"] planet_name = api[index]["pl_name"] planet_massj = api[index]["pl_bmassj"] distance = api[index]["st_dist"] print("Host:", stellar_name, "\n") print("Mass:", stellar_mass, u"M\u2609", "\n") print("Planet:", planet_name, "\n") print("Mass:", planet_massj, u"M\u1D0A", "\n") print("Distance from Earth:", distance, "pc", "\n") print("-------------------------------\n")
    submitted by /u/kurotheactivist
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    Best CPP resources?

    Posted: 01 Jan 2019 07:58 AM PST

    I'm currently looking to learn CPP and not sure where to start. What some books and/or sites I can learn cpp from?

    submitted by /u/Yooniverse1354
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    Mathematics and Physics for career growth?

    Posted: 01 Jan 2019 01:10 AM PST

    Hi, I have been programming for over 2 years, I am a web developer, and pretty decent at it. However now that I want to take on more complex projects I feel like I am awfully lacking behind in mathematics and physics. I started failing in math at 7th grade never really took any interest. When I am working with colleagues on ML projects (as a volunteer) I am usually less than useless when it comes to making a linear algorithm out of a concept we just discussed, I am somewhat able to understand the concept and logic. I tried borrowing some 7th and 6th grade level books on both Math and Physics but I can't seem to make any progress. Can anyone help me with this? I am struggling a lot here.

    submitted by /u/iamllamma
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    Whats the most efficient way to cache a personalized news feed like Twitter/Instagram for users using redis?

    Posted: 01 Jan 2019 12:41 AM PST

    Is the most efficient way to pre-cache a feed for every user? When a user posts something, do you insert the post into each of their followers' feeds?

    submitted by /u/newp
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