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• [OT] : Tagged : SQL Dream Cars

  - by AaronBertrand

  Steve Jones ( blog | twitter ) posted an entry today called "SQL Dream Cars," where he talks briefly about 5 of the cars he would love to own. He then tagged a few of us to share our lists. Before I get to mine, I wanted to reflect a bit on one of Steve's choices, the Ferrari 308 GTS. I remember when I was a kid, maybe 10 or 11 years old - after Magnum PI made that Ferrari 308 so popular - that a local doctor in North Bay had one. His name was Dr. Fazzarri (and I apologize if I've spelled that wrong);...(read more)

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• Generically correcting data before save with Entity Framework

  - by koevoeter

  Been working with Entity Framework (.NET 4.0) for a week now for a data migration job and needed some code that generically corrects string values in the database. You probably also have seen things like empty strings instead of NULL or non-trimmed texts ("United States       ") in "old" databases, and you don't want to apply a correcting function on every column you migrate. Here's how I've done this (extending the partial class of my ObjectContext):public partial class MyDatacontext{    partial void OnContextCreated()    {        SavingChanges += OnSavingChanges;    }     private void OnSavingChanges(object sender, EventArgs e)    {        foreach (var entity in GetPersistingEntities(sender))        {            foreach (var propertyInfo in GetStringProperties(entity))            {                var value = (string)propertyInfo.GetValue(entity, null);                 if (value == null)                {                    continue;                }                 if (value.Trim().Length == 0 && IsNullable(propertyInfo))                {                    propertyInfo.SetValue(entity, null, null);                }                else if (value != value.Trim())                {                    propertyInfo.SetValue(entity, value.Trim(), null);                }            }        }    }     private IEnumerable<object> GetPersistingEntities(object sender)    {        return ((ObjectContext)sender).ObjectStateManager            .GetObjectStateEntries(EntityState.Added | EntityState.Modified)             .Select(e => e.Entity);    }    private IEnumerable<PropertyInfo> GetStringProperties(object entity)    {        return entity.GetType().GetProperties()            .Where(pi => pi.PropertyType == typeof(string));    }    private bool IsNullable(PropertyInfo propertyInfo)    {        return ((EdmScalarPropertyAttribute)propertyInfo             .GetCustomAttributes(typeof(EdmScalarPropertyAttribute), false)            .Single()).IsNullable;    }}   Obviously you can use similar code for other generic corrections.

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• Surface normal to screen angle

  - by Tannz0rz

  I've been struggling to get this working. I simply wish to take a surface normal and convert it to a screen angle. As an example, assuming we're working with the highlighted surface on the sphere below, where the arrow is the normal, the 2D angle would obviously be PI/4 radians. Here's one of the many things I've tried to no avail: float4 A = v.vertex; float4 B = v.vertex + float4(v.normal, 0.0); A = mul(VP, A); B = mul(VP, B); A.xy = (0.5 * (A.xy / A.w)) + 0.5; B.xy = (0.5 * (B.xy / B.w)) + 0.5; o.theta = atan2(B.y - A.y, B.x - A.x); I'm finally at my wit's end. Thanks for any and all help.

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• Rainbows and Unicorns at the Devoxx OTN Hack Fest

  - by Tori Wieldt

  At the OTN Hack Fest at Devoxx, several developers did their first "hello world" with the Internet of Things (IoT). They had fun and built basic applications with Java Embedded, Raspberry Pi and Leap Motion controllers. Experts Yara & Vinicius Senger and Geert Bevin provided the basics and support. Geert Bevin did a bit of hacking too. Check out this video to see what he came up with a short amount of time: &amp;amp;amp;amp;lt;span id=&amp;amp;amp;amp;quot;XinhaEditingPostion&amp;amp;amp;amp;quot;&amp;amp;amp;amp;gt;&amp;amp;amp;amp;lt;/span&amp;amp;amp;amp;gt; Learn more about Java Embedded at the Oracle Technology Network. 

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• Modifying RaspberryPi as perfect linux box [on hold]

  - by Jai Hind Rubik's

  I have just bought one Raspberry pi RaspberryPi. I want to load linux kernel there. Actually my plan is to first load kernel ver sion 2.6.* after that one 3.10.* above that and in boot time I want to load 3.10.* (can choose). just after booting, I want to log in there through my windows machine using client like putty or telnet, on telnet I want see following prompt there: login as: root [email protected]'s password: ********** Last login: Thu Aug 21 22:41:07 2014 from 10.78.235.82 [root@debd ~]# [root@debd ~]#ls [root@debd ~]# Documents ... Can any one tell what kind of modification I needed to do for this? I am college student and have less knowledge managing hardware

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• RPi and Java Embedded GPIO: Connecting LEDs

  - by hinkmond

  Next, we need some low-level peripherals to connect to the Raspberry Pi GPIO header. So, we'll do what's called a "Fry's Run" in Silicon Valley, which means we go shop at the local Fry's Electronics store for parts. In this case, we'll need some breadboard jumper wires (blue wires in photo), some LEDs, and some resistors (for the RPi GPIO, 150 ohms - 300 ohms would work for the 3.3V output of the GPIO ports). And, if you want to do other projects, you might as well by a breadboard, which is a development board with lots of holes in it. Ask a Fry's clerk for help. Or, better yet, ask the customer standing next to you in the electronics components aisle for help. (Might be faster) So, go to your local hobby electronics store, or go to Fry's if you have one close by, and come back here to the next blog post to see how to hook these parts up. Hinkmond

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• Ease Rotate RigidBody2D toward arbitrary angle

  - by Plastic Sturgeon

  I'm trying to make a rigidbody2D circle return to an orientation after a collision. But there is a weird behavior I do not expect - it always orients to the same direction. This is what I call in FixedUpdate(): rotationdifference = -halfPI + rigidbody2D.rotation; rigidbody2D.AddTorque (rotationdifference * ease); I would expect this would rotate 90 degrees (1/2 Pi Radians) off of the neutral axis. But it does not. In fact it performs exactly the same as: rotationdifference = rigidbody2D.rotation; rigidbody2D.AddTorque (rotationdifference * ease); What is going on? How would I be able to set an angle I want it to ease towards, and then have it ease towards it when its not colliding with some other force?

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• What makes an application memory bandwidth bound?

  - by TheLQ

  This has been something that's been bothering me for a while: What makes an application memory bandwidth bound? For example, take this monstrosity of a computer that calculated the 5 trillionth digit of pi (and later 10 trillionth digit). I was surprised that they choose the lower but faster 98 GB RAM at 1066 MHz instead of the larger but slower 144 GB at 800 MHz. This is especially surprising considering they are using 22 TB HD array to store the results from computation; more RAM means less need for hard drives. Maybe its because I don't write applications for HPC servers, but how would RAM be the bottleneck? Are there any other non-HPC applications that usually run into this problem?

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• Devoxx Coming Up!

  - by Yolande

   Devoxx, the biggest Java conference in Europe, is  only a couple of days away. From November 12th to  16th, over 3,400 developers from all over Europe  are descending on Antwerp, Belgium for a week  focused on Java.  At the Oracle booth, Java experts will be available  to answer your  questions and demo the new  features of the Java Platform, including Java  Embedded,  JavaFX, JavaSE and Java EE.  Beer bash at the booth Tuesday from 17:30-19:30 and Wednesday/Thursday from 18:00 to 20:00. Oracle is also raffling off two Raspberry PI and books every day. Make sure to stop by  and enter the raffle during the day. Check the online schedule with sessions from the Java experts at Oracle.

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• Developer Preview of JDK8, JavaFX8 *HARD-FLOAT ABI* for Linux/ARM Now Available!

  - by HecklerMark

  Just a quick post to spread the good word: the Developer Preview of JDK8 and JavaFX8 for Linux on ARM processors - hard-float ABI - is now available here. Right here. It's been tested on the Raspberry Pi, and many of us plan to (unofficially) test it on a variety of other ARM platforms. This could be the beginning of something big. So...what are you still doing here? Go download it already! (Did I mention you could get it here?) :-D All the best,Mark

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• Get system info from C program?

  - by Hamid

  I'm writing a little program in C that I want to use to output some system stats to my HD44780 16x2 character display. The system I'll be working with is a Debian ARM system and, although irrelevant, the display is on the GPIO header.(The system is a Raspberry Pi). As an initial (somewhat unambitious) attempt, I'd like to start with something simple like RAM and CPU usage (I'm new to C). I understand that if I make external command calls I need to fork() and execve() (or some equiv that will let me return the results), what I would like to know is how I go about getting the information I want in a nice clean format that I can use. Surely I will not have to call (for e.g); free -h And then use awk or similar to chop out the piece I want? There must be a cleaner way? The question should be seen as more of a generic, what is best practice for getting info about the system in C (the RAM/CPU usage are just an initial example).

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• Arranging the colors on the board in the most pleasing form

  - by Shashwat

  Given a rectangular board of height H and width W. N colors are given. ith color occupy Pi percentage of area on the board. Sum of Pis is 1. What can be algorithm to layout the colors on the board in the form of rectangles in the most pleasing form. By pleasing mean the aspect ratios (Width/Height) of rectangle of each color should be as close to 1 as possible. In an ideal case the board would be filled only with squares.

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• Calculate random points (pixel) within a circle (image)

  - by DMills

  I have an image that contains a circles at a specific location, and of a specific diameter. What I need to do is to be able to calculate random points within the circle, and then manipulate said the pixels they correlate to. I have the following code already: private Point CalculatePoint() { var angle = _random.NextDouble() * ( Math.PI * 2 ); var x = _originX + ( _radius * Math.Cos( angle ) ); var y = _originY + ( _radius * Math.Sin( angle ) ); return new Point( ( int )x, ( int )y ); } And that works fine for finding all the points at the circumference of the circle, but I need all points from anywhere in the circle. If this doesn't make sense let me know and I will do my best to clarify.

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• MVC - Cocoa interface - Cocoa Design pattern book

  - by Idan

  So I started reading this book: http://www.amazon.com/Cocoa-Design-Patterns-Erik-Buck/dp/0321535022 On chapter 2 it explains about the MVC design pattern and gives and example which I need some clarification to. The simple example shows a view with the following fields: hourlyRate, WorkHours, Standarthours , salary. The example is devided into 3 parts : View - contains some text fiels and a table (the table contains a list of employees' data). Controller - comprised of NSArrayController class (contains an array of MyEmployee) Model - MyEmployee class which describes an employee. MyEmployee class has one method which return the salary according to the calculation logic, and attributes in accordance with the view UI controls. MyEmployee inherits from NSManagedObject. Few things i'm not sure of : 1. Inside the MyEmplpyee class implemenation file, the calculation method gets the class attributes using sentence like " [[self valueForKey:@"hourlyRate"] floatValue];" Howevern, inside the header there is no data member named hourlyRate or any of the view fields. I'm not quite sure how does it work, and how it gets the value from the right view field. (does it have to be the same name as the field name in the view). maybe the conncetion is made somehow using the Interface builder and was not shown in the book ? and more important: 2. how does it seperate the view from the model ? let's say ,as the book implies might happen, I decide one day to remove one of the fields in the view. as far as I understand, that means changing the way the salary method works in MyEmplpyee (cause we have one field less) , and removing one attribute from the same calss. So how is that separate the View from the Model if changing one reflect on the other ? I guess I get something wrong... Any comments ? Thanks

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• solve a classic map-reduce problem with opencl?

  - by liuliu

  I am trying to parallel a classic map-reduce problem (which can parallel well with MPI) with OpenCL, namely, the AMD implementation. But the result bothers me. Let me brief about the problem first. There are two type of data that flow into the system: the feature set (30 parameters for each) and the sample set (9000+ dimensions for each). It is a classic map-reduce problem in the sense that I need to calculate the score of every feature on every sample (Map). And then, sum up the overall score for every feature (Reduce). There are around 10k features and 30k samples. I tried different ways to solve the problem. First, I tried to decompose the problem by features. The problem is that the score calculation consists of random memory access (pick some of the 9000+ dimensions and do plus/subtraction calculations). Since I cannot coalesce memory access, it costs. Then, I tried to decompose the problem by samples. The problem is that to sum up overall score, all threads are competing for few score variables. It keeps overwriting the score which turns out to be incorrect. (I cannot carry out individual score first and sum up later because it requires 10k * 30k * 4 bytes). The first method I tried gives me the same performance on i7 860 CPU with 8 threads. However, I don't think the problem is unsolvable: it is remarkably similar to ray tracing problem (for which you carry out calculation that millions of rays against millions of triangles). Any ideas?

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• Powershell: Select-Object with additional calculated difference value

  - by David.Chu.ca

  Let me explain my question. I have a daily report about one PC's free space as in text file (sp.txt) like: DateTime FreeSpace(MB) ----- ------------- 03/01/2010 100.43 DateTime FreeSpace(MB) ----- ------------- 03/02/2010 98.31 .... Then I need to use this file as input to generate a report with difference of free space between dates: DateTime FreeSpace(MB) Change ----- ------------- ------ 03/01/2010 100.43 03/02/2010 98.31 2.12 .... Here are some codes I have to get above result without the additional "Change" calculation: Get-Content "C:\report\sp.txt" ` | where {$_.trim().length -gt 0 -and -not ($_ -like "Date*") -and -not ($_ -like "---*")} ` | Select-Object @{Name='DateTime'; expression={[DateTime]::Parse($_.SubString(0, 10).Trim())}}, ` @{Name='FreeSpace(MB)'; expression={$_.SubString(12, 12).Trim()}}, ` | Sort-Object DateTime ` | Select-Object DateTime, 'FreeSpace(MB)' |ft -AutoSize # how to add additional column Change to this Select-Object? My understanding is that Select-Object will return a collection of objects. Here I create this collection from an input text file(parse each line into parts: datetime and freespace(MB)). In order to calculate the difference between dates, I guess that I need to add additional calculated value to the result of the last Select-Object, or pipe the result to another Select-Object with the calculation as additional property or column. In order to do it, I need to get the previous row's FreeSpace value. Not sure if it is possible and how?

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• Calculate time of method execution and send to WCF service async

  - by Tim

  I need to implement time calculation for repository methods in my asp .net mvc project classes. The problem is that i need to send time calculation data to WCF Service which is time consuming. I think about threads which can help to cal WCF service asynchronously. But I have very little experience with it. Do I need to create new thread each time or I can create a global thread, if so then how? I have something like that: StopWatch class public class StopWatch { private DateTime _startTime; private DateTime _endTime; public void Start() { _startTime = DateTime.Now; } protected void StopTimerAndWriteStatistics() { _endTime = DateTime.Now; TimeSpan timeResult = _endTime - _startTime; //WCF proxy object var reporting = AppServerUtility.GetProxy<IReporting>(); //Send data to server reporting.WriteStatistics(_startTime, _endTime, timeResult, "some information"); } public void Stop() { //Here is the thread I have question with var thread = new Thread(StopTimerAndWriteStatistics); thread.Start(); } } Using of StopWatch class in Repository public class SomeRepository { public List<ObjectInfo> List() { StopWatch sw = new StopWatch(); sw.Start(); //performing long time operation sw.Stop(); } } What am I doing wrong with threads?

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• Concurrent cartesian product algorithm in Clojure

  - by jqno

  Is there a good algorithm to calculate the cartesian product of three seqs concurrently in Clojure? I'm working on a small hobby project in Clojure, mainly as a means to learn the language, and its concurrency features. In my project, I need to calculate the cartesian product of three seqs (and do something with the results). I found the cartesian-product function in clojure.contrib.combinatorics, which works pretty well. However, the calculation of the cartesian product turns out to be the bottleneck of the program. Therefore, I'd like to perform the calculation concurrently. Now, for the map function, there's a convenient pmap alternative that magically makes the thing concurrent. Which is cool :). Unfortunately, such a thing doesn't exist for cartesian-product. I've looked at the source code, but I can't find an easy way to make it concurrent myself. Also, I've tried to implement an algorithm myself using map, but I guess my algorithmic skills aren't what they used to be. I managed to come up with something ugly for two seqs, but three was definitely a bridge too far. So, does anyone know of an algorithm that's already concurrent, or one that I can parallelize myself?

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• Converting Milliseconds to Timecode

  - by Jeff

  I have an audio project I'm working on using BASS from Un4seen. This library uses BYTES mainly but I have a conversion in place that let's me show the current position of the song in Milliseconds. Knowing that MS = Samples * 1000 / SampleRate and that Samples = Bytes * 8 / Bits / Channels So here's my main issue and it's fairly simple... I have a function in my project that converts the Milliseconds to TimeCode in Mins:Secs:Milliseconds. Public Function ConvertMStoTimeCode(ByVal lngCurrentMSTimeValue As Long) ConvertMStoTimeCode = CheckForLeadingZero(Fix(lngCurrentMSTimeValue / 1000 / 60)) & ":" & _ CheckForLeadingZero(Int((lngCurrentMSTimeValue / 1000) Mod 60)) & ":" & _ CheckForLeadingZero(Int((lngCurrentMSTimeValue / 10) Mod 100)) End Function Now the issue comes within the Seconds calculation. Anytime the MS calculation is over .5 the seconds place rounds up to the next second. So 1.5 seconds actually prints as 2.5 seconds. I know for sure that using the Int conversion causes a round down and I know my math is correct as I've checked in a calculator 100 times. I can't figure out why the number is rounding up. Any suggestions?

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• how can I add a custom non-DataTable column to my DataView, in a winforms ADO.net application?

  - by Greg

  Hi, How could I (/is it possible) to add a custom column to my DataView, and in this column display the result of a specific calculation. That is, I currently have a dataGridView which has a binding to a DataView, based on the DataTable from my database. I'd like to add an additional column to the dataGridView to display a number which is calculated by looking at this current row plus it's children row. In other words the info for the column isn't just derivable from the row data itself. Specific questions might be: a) where to add the column itself? to the DataView I assume? b) which method / event to trigger the re-calculation of the value of this custom column from ( / how do I control this) Thanks PS. I've also noted if I use the following code/approach I get a infinite loop... // Custom Items DataColumn dc = new DataColumn("OverallSize", typeof(long)); DT_Webfiles.Columns.Add(dc); DT_Webfiles.RowChanged += new DataRowChangeEventHandler(DT_Row_Changed); private static void DT_Row_Changed(object sender, DataRowChangeEventArgs e) { e.Row["OverallSize"] = e.Row["OverallSize"] ?? 0; e.Row["OverallSize"] = (long)e.Row["OverallSize"] + 1; } What other approach could avoid this looping. i.e. currently I'm saying update the value of the custom column when the row changes, however after then changing the row it triggers antoher 'row has changed' event...

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• How to automatically read in calculated values with PHPExcel?

  - by Edward Tanguay

  I have the following Excel file: I read it in by looping over every cell and getting the value with getCell(...)->getValue(): $highestColumnAsLetters = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestColumn(); //e.g. 'AK' $highestRowNumber = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestRow(); $highestColumnAsLetters++; for ($row = 1; $row < $highestRowNumber + 1; $row++) { $dataset = array(); for ($columnAsLetters = 'A'; $columnAsLetters != $highestColumnAsLetters; $columnAsLetters++) { $dataset[] = $this->objPHPExcel->setActiveSheetIndex(0)->getCell($columnAsLetters.$row)->getValue(); if ($row == 1) { $this->column_names[] = $columnAsLetters; } } $this->datasets[] = $dataset; } However, although it reads in the data fine, it reads in the calculations literally: I understand from discussions like this one that I can use getCalculatedValue() for calculated cells. The problem is that in the Excel sheets I am importing, I do not know beforehand which cells are calculated and which are not. Is there a way for me to read in the value of a cell in a way that automatically gets the value if it has a simple value and gets the result of the calculation if it is a calculation? Answer: It turns out that getCalculatedValue() works for all cells, makes me wonder why this isn't the default for getValue() since I would think one would usually want the value of the calculations instead of the equations themselves, in any case this works: ...->getCell($columnAsLetters.$row)->getCalculatedValue();

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• Ruby 1.9 GarbageCollector, GC.disable/enable

  - by seb

  I'm developing a Rails 2.3, Ruby 1.9.1 webapplication that does quite a bunch of calculation before each request. For every request it has to calculate a graph with 300 nodes and ~1000 edges. The graph and all its nodes, edges and other objects are initialized for every request (~2000 objects) - actually they are cloned from an uncalculated cached graph using Marshal.load(Marshal.dump()). Performance is quite an issue here. Right now the whole request takes in average 150ms. I then saw that during a request, parts of the calculation randomly take longer. Assuming, that this might be the GarbageCollector kicking in, I wrapped the request in GC.disable and GC.enable, so that the request waits with garbagecollecting until calculating and rendering have finished. def query GC.disable calculate respond_to do |format| format.html {render} end GC.enable end The average request now takes about 100ms (50 ms less). But I'm unsure if this is a good/stable solution, I assume there must be drawbacks doing that. Does anybody has experience with a similar problem or sees problems with the above code?

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• jQuery Ajax load images problem

  - by jackysee

  I have a code that would call $.load() to get an HTML fragment. In the fragment there will be a list of images and a script that would do some calculation based on the list size. The fragment looks like <div> <ul> <li><img .../></li> <li><img .../></li> ... </ul> </div> <script> //... script to do calculation on the list width </script> Originally, I use css's max-width to ensure that the image would not exceed 180px. But as IE has no max-width, I use the expression hack. However, it seems when the image are first load, the script cannot get a correct width of image list. Seems like the script load earlier than the CSS expression. If it is a new page, I can certainly call $(window).load() to ensure all the images are loaded. But what can I do in an ajax html fragment request?

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• .NET Web Service hydrate custom class

  - by row1

  I am consuming an external C# Web Service method which returns a simple calculation result object like this: [Serializable] public class CalculationResult { public string Name { get; set; } public string Unit { get; set; } public decimal? Value { get; set; } } When I add a Web Reference to this service in my ASP .NET project Visual Studio is kind enough to generate a matching class so I can easily consume and work with it. I am using Castle Windsor and I may want to plug in other method of getting a calculation result object, so I want a common class CalculationResult (or ICalculationResult) in my solution which all my objects can work with, this will always match the object returned from the external Web Service 1:1. Is there anyway I can tell my Web Service client to hydrate a particular class instead of its generated one? I would rather not do it manually: foreach(var fromService in calcuationResultsFromService) { ICalculationResult calculationResult = new CalculationResult() { Name = fromService.Name }; yield return calculationResult; } Edit: I am happy to use a Service Reference type instead of the older Web Reference.

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• How to automatically read in calculated values with PHPExcel?

  - by Edward Tanguay

  I have the following Excel file: I read it in by looping over every cell and getting the value with getCell(...)->getValue(): $highestColumnAsLetters = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestColumn(); //e.g. 'AK' $highestRowNumber = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestRow(); $highestColumnAsLetters++; for ($row = 1; $row < $highestRowNumber + 1; $row++) { $dataset = array(); for ($columnAsLetters = 'A'; $columnAsLetters != $highestColumnAsLetters; $columnAsLetters++) { $dataset[] = $this->objPHPExcel->setActiveSheetIndex(0)->getCell($columnAsLetters.$row)->getValue(); if ($row == 1) { $this->column_names[] = $columnAsLetters; } } $this->datasets[] = $dataset; } However, although it reads in the data fine, it reads in the calculations literally: I understand from discussions like this one that I can use getCalculatedValue() for calculated cells. The problem is that in the Excel sheets I am importing, I do not know beforehand which cells are calculated and which are not. Is there a way for me to read in the value of a cell in a way that automatically gets the value if it has a simple value and gets the result of the calculation if it is a calculation?

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