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  • How to compute power spectrum from 2D FFT

    - by user1452954
    I've encounter a problem when doing my lab assignment, not sure how to implement this: Use fft2 on a gray image and to do Fourier transform and then compute the power spectrum. This is my code so far: >> Pc = imread('pckint.jpg'); >> whos Pc; Name Size Bytes Class Attributes Pc 256x256 65536 uint8 >> imshow(Pc); >> result = fft2(Pc); My question is from the result. How to computer power spectrum?

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  • Quickest way to compute the number of shared elements between two vectors

    - by shn
    Suppose I have two vectors of the same size vector< pair<float, NodeDataID> > v1, v2; I want to compute how many elements from both v1 and v2 have the same NodeDataID. For example if v1 = {<3.7, 22>, <2.22, 64>, <1.9, 29>, <0.8, 7>}, and v2 = {<1.66, 7>, <0.03, 9>, <5.65, 64>, <4.9, 11>}, then I want to return 2 because there are two elements from v1 and v2 that share the same NodeDataIDs: 7 and 64. What is the quickest way to do that in C++ ? Just for information, note that the type NodeDataIDs is defined as I use boost as: typedef adjacency_list<setS, setS, undirectedS, NodeData, EdgeData> myGraph; typedef myGraph::vertex_descriptor NodeDataID; But it is not important since we can compare two NodeDataID using the operator == (that is, possible to do v1[i].second == v2[j].second)

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  • Selecting a user-defined scalar function that takes as a parameter another field

    - by ghills
    I have a table a with a list of id's, and a user-defined function foo(id) that takes the id and returns a VARCHAR(20). What I am trying to do is: SELECT id, foo(id) AS 'text field' FROM a However, instead of calling the function for each ID number, like I desired, the text comes back the same for every row. I have tested the foo() function manually with the returned ID's and it does not have that problem, so I realize I must not understand something about the evaluation of the query.

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  • How to call a scalar function in a stored procedure

    - by Luke101
    I am wacking y head over the problem with this code. DECLARE @root hierarchyid declare @lastchild hierarchyid SELECT @root = NodeHierarchyID from NodeHierarchy where ID = 1 set @lastchild = getlastchild(@root) it says it does not recognize getlastchild function. What am I doing wrong here

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  • How to improve performance of non-scalar aggregations on denormalized tables

    - by The Lazy DBA
    Suppose we have a denormalized table with about 80 columns, and grows at the rate of ~10 million rows (about 5GB) per month. We currently have 3 1/2 years of data (~400M rows, ~200GB). We create a clustered index to best suit retrieving data from the table on the following columns that serve as our primary key... [FileDate] ASC, [Region] ASC, [KeyValue1] ASC, [KeyValue2] ASC ... because when we query the table, we always have the entire primary key. So these queries always result in clustered index seeks and are therefore very fast, and fragmentation is kept to a minimum. However, we do have a situation where we want to get the most recent FileDate for every Region, typically for reports, i.e. SELECT [Region] , MAX([FileDate]) AS [FileDate] FROM HugeTable GROUP BY [Region] The "best" solution I can come up to this is to create a non-clustered index on Region. Although it means an additional insert on the table during loads, the hit isn't minimal (we load 4 times per day, so fewer than 100,000 additional index inserts per load). Since the table is also partitioned by FileDate, results to our query come back quickly enough (200ms or so), and that result set is cached until the next load. However I'm guessing that someone with more data warehousing experience might have a solution that's more optimal, as this, for some reason, doesn't "feel right".

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  • How can I modify a scalar reference passed to a subroutine reference

    - by Mark
    I have a function to convert documents into different formats, which then calls another function based on the type document. It's pretty straight forward for everything aside from HTML documents which require a bit of cleaning up, and that cleaning up is different based on where it's come from. So I had the idea that I could pass a reference to a subroutine to the convert function so the caller has the opportunity to modify the HTML, kinda like so (I'm not at work so this isn't copy-and-pasted): package Converter; ... sub convert { my ($self, $filename, $coderef) = @_; if ($filename =~ /html?$/i) { $self->_convert_html($filename, $coderef); } } sub _convert_html { my ($self, $filename, $coderef) = @_; my $html = $self->slurp($filename); $coderef->(\$html); #this modifies the html $self->save_to_file($filename, $html); } which is then called by: Converter->new->convert("./whatever.html", sub { s/<html>/<xml>/i }); I've tried a couple of different things along these lines but I keep on getting 'Use of uninitialized value in substitution (s///)'. Is there any way of doing what I'm trying to do? Thanks

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  • How do I get a scalar value from a stored proc using Nettiers

    - by Micah
    I have a really simple stored procedure that looks like this: CREATE PROCEDURE _Visitor_GetVisitorIDByVisitorGUID ( @VisitorGUID AS UNIQUEIDENTIFIER ) AS DECLARE @VisitorID AS bigint SELECT @VisitorID = VisitorID FROM dbo.Visitor WHERE VisitorGUID = @VisitorGUID --Here's what I've tried RETURN @VisitorID 'Returns an IDataReader SELECT @VisitorID 'Returns an IDataReader --I've also set it up with a single output --parameter, but that means I need to pass --the long in by ref and that's hideous to me I'm trying to get nettiers to generate a method with this signature: public long VisitorService.GetVisitorIDByVisitorGUID(GUID visitorGUID); Basically I want Nettiers to call ExecuteScalar instead of ExecuteReader. What am I doing wrong?

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  • Return nullable datetime from scalar, stored procedure

    - by molgan
    Hello I have a function that returns a date from a stored procedure, and it all works great til the value is NULL, how can I fix this so it works with null aswell? public DateTime? GetSomteDate(int SomeID) { DateTime? LimitDate= null; if (_entities.Connection.State == System.Data.ConnectionState.Closed) _entities.Connection.Open(); using (EntityCommand c = new EntityCommand("MyEntities.GetSomeDate", (EntityConnection)this._entities.Connection)) { c.CommandType = System.Data.CommandType.StoredProcedure; EntityParameter paramSomeID = new EntityParameter("SomeID", System.Data.DbType.Int32); paramSomeID.Direction = System.Data.ParameterDirection.Input; paramSomeID.Value = SomeID; c.Parameters.Add(paramSomeID); var x = c.ExecuteScalar(); if (x != null) LimitDate = (DateTime)x; return LimitDate.Value; }; }

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  • System.Data.SqlClient.SqlException: Must declare the scalar variable "@"

    - by Owala Wilson
    Haloo everyone...I am new to asp.net and I have been trying to query one table, and if the value returns true execute another query. here is my code: protected void Button1_Click(object sender, EventArgs e) { SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyServer"].ConnectionString); SqlConnection con1 = new SqlConnection(ConfigurationManager.ConnectionStrings["MyServer"].ConnectionString); int amounts = Convert.ToInt32(InstallmentPaidBox.Text) + Convert.ToInt32(InterestPaid.Text) + Convert.ToInt32(PenaltyPaid.Text); int loans = Convert.ToInt32(PrincipalPaid.Text) + Convert.ToInt32(InterestPaid.Text); con.Open(); DateTime date = Convert.ToDateTime(DateOfProcessing.Text); int month1 = Convert.ToInt32(date.Month); int year1 = Convert.ToInt32(date.Year); SqlCommand a = new SqlCommand("Select Date,max(Amount)as Amount from Minimum_Amount group by Date",con); SqlDataReader sq = a.ExecuteReader(); while (sq.Read()) { DateTime date2 = Convert.ToDateTime(sq["Date"]); int month2 = Convert.ToInt32(date2.Month); int year2 = Convert.ToInt32(date2.Year); if (month1 == month2 && year1 == year2) { int amount = Convert.ToInt32(sq["Amount"]); string scrip = "<script>alert('Data Successfully Added')</script>"; Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "Added", scrip); int areas = amount - Convert.ToInt32(InstallmentPaidBox.Text); int forwarded = Convert.ToInt32(BalanceBroughtTextBox.Text) + Convert.ToInt32(InstallmentPaidBox.Text); if (firsttime.Checked) { int balance = areas + Convert.ToInt32(PenaltyDue.Text) + Convert.ToInt32(InterestDue.Text); SqlCommand cmd = new SqlCommand("insert into Cash_Position(Member_No,Welfare_Amount, BFWD,Amount,Installment_Paid,Loan_Repayment,Principal_Payment,Interest_Paid,Interest_Due,Loan_Balance,Penalty_Paid,Penalty_Due,Installment_Arrears,CFWD,Balance_Due,Date_Prepared,Prepared_By) values(@a,@b,@c,@d,@e,@)f,@g,@h,@i,@j,@k,@l,@m,@n,@o,@p,@q", con); cmd.Parameters.Add("@a", SqlDbType.Int).Value = MemberNumberTextBox.Text; cmd.Parameters.Add("@b", SqlDbType.Int).Value = WelfareAmount.Text; cmd.Parameters.Add("@c", SqlDbType.Int).Value = BalanceBroughtTextBox.Text; cmd.Parameters.Add("@d", SqlDbType.Int).Value = amounts; cmd.Parameters.Add("@e", SqlDbType.Int).Value = InstallmentPaidBox.Text; cmd.Parameters.Add("@f", SqlDbType.Int).Value = loans; cmd.Parameters.Add("@g", SqlDbType.Int).Value = PrincipalPaid.Text; cmd.Parameters.Add("@h", SqlDbType.Int).Value = InterestDue.Text; cmd.Parameters.Add("@i", SqlDbType.Int).Value = InterestDue.Text; cmd.Parameters.Add("@j", SqlDbType.Int).Value = 0; cmd.Parameters.Add("@k", SqlDbType.Int).Value = PenaltyPaid.Text; cmd.Parameters.Add("@l", SqlDbType.Int).Value = PenaltyDue.Text; cmd.Parameters.Add("@m", SqlDbType.Int).Value = areas; cmd.Parameters.Add("@n", SqlDbType.Int).Value = forwarded; cmd.Parameters.Add("@o", SqlDbType.Int).Value = balance; cmd.Parameters.Add("@p", SqlDbType.Date).Value = date; cmd.Parameters.Add("@q", SqlDbType.Text).Value = PreparedBy.Text; int rows = cmd.ExecuteNonQuery(); con.Close();

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  • Compute the Length of Largest substring that starts and ends with the same substring

    - by Deepak
    Hi People, Below is the Problem Statement: PS: Given a string and a non-empty substring sub, compute recursively the largest substring which starts and ends with sub and return its length. Examples: strDist("catcowcat", "cat") ? 9 strDist("catcowcat", "cow") ? 3 strDist("cccatcowcatxx", "cat") ? 9 Below is my Code: (Without recursion)//since i found it hard to implement with recursion. public int strDist(String str, String sub){ int idx = 0; int max; if (str.isEmpty()) max = 0; else max=1; while ((idx = str.indexOf(sub, idx)) != -1){ int previous=str.indexOf(sub, idx); max = Math.max(max,previous); idx++; } return max; } Its working for few as shown below but returns FAIL for others. Expected This Run strDist("catcowcat", "cat") ? 9 6 FAIL strDist("catcowcat", "cow") ? 3 3 OK strDist("cccatcowcatxx", "cat") ? 9 8 FAIL strDist("abccatcowcatcatxyz", "cat") ? 12 12 OK strDist("xyx", "x") ? 3 2 FAIL strDist("xyx", "y") ? 1 1 OK strDist("xyx", "z") ? 0 1 FAIL strDist("z", "z") ? 1 1 OK strDist("x", "z") ? 0 1 FAIL strDist("", "z") ? 0 0 OK strDist("hiHellohihihi", "hi") ? 13 11 FAIL strDist("hiHellohihihi", "hih") ? 5 9 FAIL strDist("hiHellohihihi", "o") ? 1 6 FAIL strDist("hiHellohihihi", "ll") ? 2 4 FAIL Could you let me whats wrong with the code and how to return the largest substring that begins and ends with sub with its respective length.

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  • OpenCL - incremental summation during compute

    - by user1721997
    I'm absolutelly novice in OpenCL programming. For my app. (molecular simulaton) I wrote a kernel for calculate intermolecular potential of lennard-jones liquid. In this kernel I need to compute cumulative value of the potential of all particles with one: __kernel void Molsim(__global const float* inmatrix, __global float* fi, const int c, const float r1, const float r2, const float r3, const float rc, const float epsilon, const float sigma, const float h1, const float h23) { float fi0; float fi1; float d; unsigned int i = get_global_id(0); //number of particles (typically 2000) if(c!=i) { // potential before particle movement d=sqrt(pow((0.5*h1-fabs(0.5*h1-fabs(inmatrix[c*3]-inmatrix[i*3]))),2.0)+pow((0.5*h23-fabs(0.5*h23-fabs(inmatrix[c*3+1]-inmatrix[i*3+1]))),2.0)+pow((0.5*h23-fabs(0.5*h23-fabs(inmatrix[c*3+2]-inmatrix[i*3+2]))),2.0)); if(d<rc) { fi0=4.0*epsilon*(pow(sigma/d,12.0)-pow(sigma/d,6.0)); } else { fi0=0; } // potential after particle movement d=sqrt(pow((0.5*h1-fabs(0.5*h1-fabs(r1-inmatrix[i*3]))),2.0)+pow((0.5*h23-fabs(0.5*h23-fabs(r2-inmatrix[i*3+1]))),2.0)+pow((0.5*h23-fabs(0.5*h23-fabs(r3-inmatrix[i*3+2]))),2.0)); if(d<rc) { fi1=4.0*epsilon*(pow(sigma/d,12.0)-pow(sigma/d,6.0)); } else { fi1=0; } // cumulative difference of potentials fi[0]+=fi1-fi0; } } My problem is in the line: fi[0]+=fi1-fi0;. In the one-element vector fi[0] are wrong results. I read something about sum reduction, but I do not know how to do it during the calculation. Exist any simple solution of my problem?

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  • C++: compute a number's complement and its number of possible mismatches

    - by Eagle
    I got a bit stuck with my algorithm and I need some help to solve my problem. I think an example would explain better my problem. Assuming: d = 4 (maximum number of allowed bits in a number, 2^4-1=15). m_max = 1 (maximum number of allowed bits mismatches). kappa = (maximum number of elements to find for a given d and m, where m in m_max) The main idea is for a given number, x, to compute its complement number (in binary base) and all the possible combinations for up to m_max mismatches from x complement's number. Now the program start to scan from i = 0 till 15. for i = 0 and m = 0, kappa = \binom{d}{0} = 1 (this called a perfect match) possible combinations in bits, is only 1111 (for 0: 0000). for i = 0 and m = 1, kappa = \binom{d}{1} = 4 (one mismatch) possible combinations in bits are: 1000, 0100, 0010 and 0001 My problem was to generalize it to general d and m. I wrote the following code: #include <stdlib.h> #include <iomanip> #include <boost/math/special_functions/binomial.hpp> #include <iostream> #include <stdint.h> #include <vector> namespace vec { typedef std::vector<unsigned int> uint_1d_vec_t; } int main( int argc, char* argv[] ) { int counter, d, m; unsigned num_combination, bits_mask, bit_mask, max_num_mismatch; uint_1d_vec_t kappa; d = 4; m = 2; bits_mask = 2^num_bits - 1; for ( unsigned i = 0 ; i < num_elemets ; i++ ) { counter = 0; for ( unsigned m = 0 ; m < max_num_mismatch ; m++ ) { // maximum number of allowed combinations num_combination = boost::math::binomial_coefficient<double>( static_cast<unsigned>( d ), static_cast<unsigned>(m) ); kappa.push_back( num_combination ); for ( unsigned j = 0 ; j < kappa.at(m) ; j++ ) { if ( m == 0 ) v[i][counter++] = i^bits_mask; // M_0 else { bit_mask = 1 << ( num_bits - j ); v[i][counter++] = v[i][0] ^ bits_mask } } } } return 0; } I got stuck in the line v[i][counter++] = v[i][0] ^ bits_mask since I was unable to generalize my algorithm to m_max1, since I needed for m_max mismatches m_max loops and in my original problem, m is unknown until runtime.

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  • T-SQL: Compute Subtotals For A Range Of Rows

    - by John Dibling
    MSSQL 2008. I am trying to construct a SQL statement which returns the total of column B for all rows where column A is between 2 known ranges. The range is a sliding window, and should be recomputed as it might be using a loop. Here is an example of what I'm trying to do, much simplified from my actual problem. Suppose I have this data: table: Test Year Sales ----------- ----------- 2000 200 2001 200 2002 200 2003 200 2004 200 2005 200 2006 200 2007 200 2008 200 2009 200 2010 200 2011 200 2012 200 2013 200 2014 200 2015 200 2016 200 2017 200 2018 200 2019 200 I want to construct a query which returns 1 row for every decade in the above table, like this: Desired Results: DecadeEnd TotalSales --------- ---------- 2009 2000 2010 2000 Where the first row is all the sales for the years 2000-2009, the second for years 2010-2019. The DecadeEnd is a sliding window that moves forward by a set ammount for each row in the result set. To illustrate, here is one way I can accomplish this using a loop: declare @startYear int set @startYear = (select top(1) [Year] from Test order by [Year] asc) declare @endYear int set @endYear = (select top(1) [Year] from Test order by [Year] desc) select @startYear, @endYear create table DecadeSummary (DecadeEnd int, TtlSales int) declare @i int -- first decade ends 9 years after the first data point set @i = (@startYear + 9) while @i <= @endYear begin declare @ttlSalesThisDecade int set @ttlSalesThisDecade = (select SUM(Sales) from Test where(Year <= @i and Year >= (@i-9))) insert into DecadeSummary values(@i, @ttlSalesThisDecade) set @i = (@i + 9) end select * from DecadeSummary This returns the data I want: DecadeEnd TtlSales ----------- ----------- 2009 2000 2018 2000 But it is very inefficient. How can I construct such a query?

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  • Compute bounding quad of a sphere with vertex shader

    - by Ben Jones
    I'm trying to implement an algorithm from a graphics paper and part of the algorithm is rendering spheres of known radius to a buffer. They say that they render the spheres by computing the location and size in a vertex shader and then doing appropriate shading in a fragment shader. Any guesses as to how they actually did this? The position and radius are known in world coordinates and the projection is perspective. Does that mean that the sphere will be projected as a circle? Thanks!

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  • Compute average distance from point to line segment and line segment to line segment

    - by Fred
    Hi everyone, I'm searching for an algorithm to calculate the average distance between a point and a line segment in 3D. So given two points A(x1, y1, z1) and B(x2, y2, z2) that represent line segment AB, and a third point C(x3, y3, z3), what is the average distance between each point on AB to point C? I'm also interested in the average distance between two line segments. So given segment AB and CD, what is the average distance from each point on AB to the closest point on CD? I haven't had any luck with the web searches I've tried, so any suggestions would be appreciated. Thanks.

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  • Fastest way to compute a "Visual" checksum of an image

    - by ensnare
    I'm looking to create an ID system for cataloging images. I can't use md5() since that will change if I alter the EXIF tags of the image. I am currently using the SHA1 checksum computed by imagemagick. It works perfectly, but it's really, really slow on larger images (~15 seconds on a quad-core xeon for a 21 megapixel JPG). Are there any other "visual" methods of uniquely identifying an image that would be faster? Thank you.

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  • Compute weighted averages for large numbers

    - by Travis
    I'm trying to get the weighted average of a few numbers. Basically I have: Price - 134.42 Quantity - 15236545 There can be as few as one or two or as many as fifty or sixty pairs of prices and quantities. I need to figure out the weighted average of the price. Basically, the weighted average should give very little weight to pairs like Price - 100000000.00 Quantity - 3 and more to the pair above. The formula I currently have is: ((price)(quantity) + (price)(quantity) + ...)/totalQuantity So far I have this done: double optimalPrice = 0; int totalQuantity = 0; double rolling = 0; System.out.println(rolling); Iterator it = orders.entrySet().iterator(); while(it.hasNext()) { System.out.println("inside"); Map.Entry order = (Map.Entry)it.next(); double price = (Double)order.getKey(); int quantity = (Integer)order.getValue(); System.out.println(price + " " + quantity); rolling += price * quantity; totalQuantity += quantity; System.out.println(rolling); } System.out.println(rolling); return totalQuantity / rolling; The problem is I very quickly max out the "rolling" variable. How can I actually get my weighted average? Thanks!

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  • Compute divergence of vector field using python

    - by nyvltak
    Is there a function that could be used for calculation of the divergence of the vectorial field? (in matlab http://www.mathworks.ch/help/techdoc/ref/divergence.html) I would expect it exists in numpy/scipy but I can not find it using google :(. # I need to calculate div[A * grad(F)], where F = np.array([[1,2,3,4],[5,6,7,8]]) (2D numpy ndarray) A = np.array([[1,2,3,4],[1,2,3,4]]) (2D numpy ndarray) so grad(F) is a set of 2D ndarrays # I know, I can calculate divergence like this: http://en.wikipedia.org/wiki/Divergence#Application_in_Cartesian_coordinates but do not want to reinvent the wheel. (and also I expent there is some optimized function)

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  • How to Compute a Database Column in .NET

    - by Michael
    I have a Database named CarsType.accdb there are four fields in the data base Item_Name, Item_Num, Item_Qty, Item_Cost. I am able to get the database to display my data in VisualBasic but I am not sure how to get the total cost to appear in my label (lblTotalCost). I prefer doing it in VB versus writing in my access program. All I am wanting to do it multiply item_qty * Item_Cost How would I go about doing that?

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  • CUDA - multiple kernels to compute a single value

    - by Roger
    Hey, I'm trying to write a kernel to essentially do the following in C float sum = 0.0; for(int i = 0; i < N; i++){ sum += valueArray[i]*valueArray[i]; } sum += sum / N; At the moment I have this inside my kernel, but it is not giving correct values. int i0 = blockIdx.x * blockDim.x + threadIdx.x; for(int i=i0; i<N; i += blockDim.x*gridDim.x){ *d_sum += d_valueArray[i]*d_valueArray[i]; } *d_sum= __fdividef(*d_sum, N); The code used to call the kernel is kernelName<<<64,128>>>(N, d_valueArray, d_sum); cudaMemcpy(&sum, d_sum, sizeof(float) , cudaMemcpyDeviceToHost); I think that each kernel is calculating a partial sum, but the final divide statement is not taking into account the accumulated value from each of the threads. Every kernel is producing it's own final value for d_sum? Does anyone know how could I go about doing this in an efficient way? Maybe using shared memory between threads? I'm very new to GPU programming. Cheers

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  • Compute jvm heap size to host web application

    - by Enrique
    Hello, I want to host a web application on a private JVM they offer 32, 64, 128, 256 MB plans. My web application uses Spring. And I store some objects for every logged in user session. My question is: How can I profile my web app to see how much heap size it needs so I can choose a plan?, How can I simulate hundreds of users logged in at the same time? I'm developing the application using Netbeans 6.7 Java 1.6 Tomcat 6.0.18 Thank you.

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  • Compute column widths in a HTML-like manner (based on cell contents)

    - by cipak
    Hi, I have a grid of data that I want to export to RTF, PDF etc. using various (and not perfect) PHP converters/generators. What I am missing most is the HTML table automatic adjustment of column widths based on the lengths of strings in the cells (strings contain line breaks which complicate things a bit, as they should be preserved). I need an algorithm that, given the contents of the cells (plain text), a total width of the table and an average width of a character, would return a width for each column. I wouldn't want to reinvent the wheel if something is already available. Of course it can't be perfect if the font is variable width, but an approximation would do just fine. Or maybe it could have a configurable table with widths for each character. Any hint would be appreciated. Thank you.

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