C++ :: Normal Distribution Range - Select Objects On A Vector
May 23, 2014
I'm implementing an normal_distribution to select objects on a vector. The thing is I can't use values greater then 1 or less then -1. Here is what could be done:
The question is if the distribution would loose it's power to be a normal distribution, because some of the gerated numbers wouldn't be used. Any way to set ranges for the distribution?
Write a function that generates 1000 normally distributed (Gaussian Probability Distribution) random numbers. Range should be between -3 and +3. Numbers should be double floating point.
There's more to it than that, but I've got it from there.
I wrote the following program shown below that produces a normally distributed random number several times, and then takes the average of them. The problem that I have been having though is that the output it has been producing is 0.0288385 despite the fact that I set the mean of the normal distribution to be 0.1. Why this output value would be so far off from 0.1 despite having averaged over such a large number of random numbers namely 10,000 of them? Also, how to randomly seed this random number generator such that it gives a different value each time its run perhaps by seeding it with the windows timer? Below is the program.
#include <iostream> #include <random> using namespace std; int main() { default_random_engine generator; normal_distribution<double> distribution1(0.1,3.0); double number1,sum,n;
I need creating a unique form of binary tree. I will eventually drop 256 balls into this to see the distribution, but its creating a pascals triangle recursively.
To create it I need to use two classes, a tree and a node class, and friend them create it recursively.
I need to construct Truncated Gaussian distribution in the range of (5-20 microns), specifyed by initial standard deviation.
Particularly i need input which comprises of minimum value(5 microns), maximum value(20 microns) and standard deviation of (5,10,20 etc..). In this regard i tried with Box-Muller but it doesn't fulfuil the goal.
In my problem I am to create a base class to represent a four vector (a concept in physics involving a four dimensional vector) then create a derived class specifically to represent the four momentum of a particle which inherits from the base class. I have been supplied a small piece of code to use to generate a 'random' x y and z component of the momentum magnitude. The code is as follows
#include <cstdlib> double triangular(double momentum){ double x, y; do{ x = momentum*rand()/RAND_MAX; y = x/momentum; } while (1.0*rand()/RAND_MAX > y); return x; }
It is said in my problem that this code is supposed to generate the magnitude, and then randomly split into x, y and z components. This code returns a single value and so I cannot see how it is doing what it says in the problem.
I am working on my second c++ project that is a statistical analysis of a vector data set of integers. I created a struct called range with a maximum value, minimum value and count for occurrence. The frequencies are stored in a vector<range>.
I have tried messing around with the increment to get the high range test above the maximum element, though my ranges cumulatively increase by 9.9. I'm not sure how the professor's program has the distance between high and low ranges as 10 instead of 9.9, which is the increment. I'm also unsure why half way through his buckets, the ranges appear as 9.99 briefly and then return to 10 after (40.00 - 49.99 then 49.99 - 59.99). I feel like I am missing something very obvious on line 04 or 10 in my code.
Here is the code for the frequency that accepts a vector reference for my data set of integers.
I'm making a simple game and I'm having trouble creating boundaries for the players movements. The map is a 2D vector. When I compare the vector with the players current position sometimes I get an error during run. When the error isn't occurring the behavior of the boundaries is bizarre. The error tells me that the vector is out of range.
Here is the where the map is created. It's within its own class constructor.
vector< vector<char> > map_parts; map_parts.resize(25); for ( int i = 0; i < 25; i++ ) {
I'm trying to do some operator overloading, the function is supposed to add the values at index [i] of two vectors and place the result in the returning vector. The problem is I keep getting a vector out of range. This is the overloaded operator I'm working with (relatively new to these):
vector<float> operator+(const vector<float>& a, const vector<float>& b){ unsigned long size; vector<float> temp; if(a.size() >= b.size()) size = a.size();
[Code] .....
and then I would do something like this in the main:
vector<float> v, v1, v2;
v1.push_back(9.1); ... v2.push_back(8); ... v = v1 + v2;
but when I try to output the vector v I just get a vector out of range exception.
When i build this program i get no errors, however a message appears saying vector subscript out of range. What does this mean and what can i do to mkae my program work
Suppose I have a stl vector of ints, and I want to pass a sub-range of that vector as an argument to a function. One way of doing that would be to copy the sub-range, and then pass that copy by reference, as follows:
Code: #include <vector> using namespace std; int MyFunction(vector<int> &a_vector) { // Do something return 0;
[Code] ....
However, it can be time-consuming to copy the elements between the two vectors if my_vector is large. So I'm wondering if it is possible to directly pass a sub-range of my_vector by reference, without having to create a new vector and manually copy over all of the relevant elements?
I will try my best to describe this problem I am having because I am not sure if I can reproduce the error in a small code example as this is part of a large code project.
I have a plain std::vector which contains pointers to objects.
When attempting to delete the objects, even if I know for a fact that the std::vector has at least one object in it as shown by the debugger, I get the "Vector Subscript Out of Range" error.
I'll even do a range for loop like so:
for (auto & e : CurrentObjects) { delete e; }
And yet I still get the "Vector Subscript Out of Range" error. The destructor is never called for the object represented by "e" so I am not sure why I get the error.
You are to write a C++ program to generate random integers in the range [ LOW = 1, HIGH = 10000 ] and to store them in a vector < int > of size VEC_SIZE = 250. Then, sort the contents of the vector (in ascending order) and display it on stdout.
To sort the contents of a vector, use the sort ( ) function from the STL. In addition to the main ( ) routine, implement the following subroutines in your program:
• void genRndNums ( vector < int >& v ) : This routine generates VEC_SIZE integers and puts them in vector v. Initializes the random number generator (RNG) by calling the function srand ( ) with the seed value SEED = 1, and generates random integers by calling the function rand ( ).
• void printVec ( const vector < int >& v ) : This routine displays the contents of vector v on stdout, printing exactly NO_ITEMS = 12 numbers on a single line, except perhaps the last line. The sorted numbers need to be properly aligned on the output. For each printed number, allocate ITEM_W = 5 spaces on stdout.
Programming Notes:
• You are not allowed to use any I/O functions from the C library, such as scanf or printf. Instead, use the I/O functions from the C++ library, such as cin or cout. • Let v be a vector of integers, then the call: sort ( v.begin ( ), v.end ( ) ) sorts the elements of v in ascending order. The detailed description of the sort ( ) routine can be found on the course web site and in the course textbook. • Execute the srand ( ) function only once before generating the first random integer with the given seed value SEED. The rand ( ) function generates a random integer in the range [ 0, RAND_MAX ], where the constant value RAND_MAX is the largest random integer returned by the rand ( ) function and its value is system dependent. To normalize the return value to a value in the range [ LOW, HIGH ], execute: rand ( ) % ( HIGH – LOW + 1 ) + LOW.
I have the following code. however, when I debug it gives an error saying" vector subscript out of range"
Vector based mufti-dimensional arrays
Vectors are a STL container that allow you to store pretty much anything in them. When used correctly they can be very powerful containers.
They provide an added benefit that they will automatically remove the memory they use when they go out of scope. This means that objects stored within a vector do not need to be de-allocated (but pointers to objects do). You can also do some interesting things with dynamic multidimensional arrays with vectors.
For example, if you only allocate the first dimension, then use the .push_back() to add records to the 2nd dimension it's no longer a grid, but an array with a dynamically sized 2nd dimension (much like a street of buildings each with a different amount of floors).
This functionality can be achieved using pointers, but is much harder to do.
#include <iostream> #include <vector> #include<conio.h> using std::vector; using namespace std;
I've been really busy but managed to get in enough down time to learn somewhat decent info about vectors. Anyways originally my program created a dynamic array of pointers to class objects and I came across a few problems because of this. Apparently an array of pointers is now outta of the question and I will now be switching to a vector of objects instead.
Why I want a list of objects instead of pointers this little comment should clear things up.
tiles[i]->show() dereferences tiles[i] (i.e. accesses whatever it points at) before calling the show() method.
That is undefined behaviour. Once undefined behaviour occurs, there is no recovery, and there is nothing the show() method (or any subsequently called function for that matter) can do to recover (short of invoking their own forms of undefined behaviour - compiler specific hacks, etc).
Even if the show() method initialises the object correctly, it cannot change the pointer tiles[i] which is in a different scope (within main()).
What I'm trying to do is create a vector of already intialized objects so that I can use a conditional statement of every single element to properly layer my games art resources. This should also automatically fix a mild unrelated collision dectection problem too but first thing first layering.
here's the problem. I want to delete the objects within a vector, although I'm not sure whether I should clear the vector afterwards. Is it really necessary?
Code:
for (i = 0; i < allSales.size(); i++) delete allSales[i];
I have two classes, Parent and Child, where Parent contains a vector that is used to store instances of Child. When I create an instance of Parent, three instances of Child are also created in Parent's constructor and stored in the vector. I understand that push_back() creates a shallow copy of each Child instance and that Child's destructor is called each time the loop (inside Parent's constructor) iterates. The problem is that because Child's destructor is called each time the local variable child goes out of scope, the memory previously allocated in Child's constructor is destroyed and when Child's destructor is called again later on in the program to get rid of the copy stored in vector, the program crashes. I can fix this by overriding the default copy function or by storing pointers to objects instead of copies of objects. I don't really need to use vectors in this case since I always have three children in one parent but I'm doing this as a learning exercise and would prefer to use vectors.
I'm implementing kruskal's algorithm and ran into some troubles compiling. I need to sort a vector of objects by value. Here is my code and the error I'm getting.
Code:
These are the two functions in graph.cpp (there are more but are unrelated)
#include <vector> #include <algorithm> #include <iostream> using namespace std; #include "graph.h" #include "edge.h" using std::vector; void graph::sort_edgesArray() {
[code].....
//This is the error I'm getting.
graph.cpp: In member function "void graph::sort_edgesArray()": graph.cpp:39:33: error: no matching function for call to sort (std::vector<edge>::iterator&, std::vector<edge>::iterator&, <unresolved overloaded function type>) /usr/include/c++/4.5/bits/stl_algo.h:5236:18: note: candidate is: void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<edge*, std::vector<edge> >, _Compare = bool (graph::*)(edge&, edge&)]
I'm working on a code for ascertaining the minimum penalty of an assignment problem. The basic complication of my code is this: I have a vector of objects of a custom struct. The struct has a member, which is an integer. I need to keep the vector sorted according to that member, even when objects are added to or deleted from the vector. To illustrate the problem, I'll give an example.
Code:
typedef struct examplestruct{int i; char c; ...} es; int function(void) {vector<es> ObjectTable; //insert an object so that the vector remains sorted according to i insertobject( newobject, &ObjectTable); //deleting the top element of the vector deleteobject(&ObjectTable); return 0;}
I have tried to do it using bubblesort. But it's too slow. How to make a heap out of it.
The detailed premises of the problem is this: There are a number of jobs, and with each job a completion time and a cost coefficient. We are to ascertain the optimal sequence of jobs for which the penalty is minimum. Now, suppose we are given jobs A, B, C, D and E. We find out the lower bound of penalties for all the jobs.
Suppose we find B has the lowest penalty. Then we find out the lower bound of penalties for BA, BC, BD and BE. We continue this until we have the best value and a complete sequence. The way I have implemented this in a code: I have created two structs. One is Job, with the completion time and cost coefficient as members. The other is Node. Nodes have a Job Array and a Penalty as members. Now, we have a vector of Nodes which we need to keep sorted according to the penalty. We need to insert new Nodes and delete the expanded Nodes.
I have included my code. The pushInTable function inserts the new Nodes in a sorted vector. But it slows down remarkably when we give more than 20 jobs as input.
For a beginners C++ lab, I have a base class Employee and two derived classes HourlyEmployee and SalaryEmployee. In main, I have a vector defined as vector <Employee *> VEmp; It's then passed to a function to get the input, which works fine. But what I'm struggling with is another function with the header "printList(const vector <Employee *> & Ve)". It's supposed to loop through the vector and call the appropriate printPay function, which is a seperate print function inside each derived class. How do I loop through the vector and print it out? I was trying to do a for loop and something like "Ve[i].printPay();", but that doesn't work. So how would I do it?
Here's some snippets of the relevant code.
class Employee { .... virtual void printPay() = 0; }; class HourlyEmployee : public Employee {
