Replace This While Loop with More Efficient Code? - excel

The below code copies the named range "MasterLLTable" n times where n is the difference between the two integers NumTables and UserNumTables. n can be in the hundreds, so the loop can take many seconds to run. Is there a way to speed this operation up by replacing the While loop with something more efficient? Need to make n copies of "MasterLLTable" without the While loop if possible. Also, the spacing between the tables must be preserved.
Do While NumTables < UserNumTables
Range("MasterLLTable").Copy EIRPLL.Cells(LastLLRow + 2, 2)
LastLLRow = EIRPLL.UsedRange.Rows.Count
NumTables = (EIRPLL.UsedRange.Rows.Count - 4) / 15
Loop

That code is fairly optimal, there are things in it you could nitpick, however that is most likely NOT what is causing the slow execution you see. VBA is inherently slow because of all the interop that takes place. However, you can speed it up with a few tricks:
First, set Application.Calculation = xlCalculationManual before executing the loop, then Application.Calculation = xlCalculationAutomatic after the loop executes. This will stop excel from calculating each and every cell after each paste operation.
Second, you can set Application.ScreenUpdating = FALSE around the same time you set Application.Calculation, this will stop the GUI from updating anything while the script is running. Once the loop is complete (or the script), set Application.ScreenUpdating = TRUE to let Excel start doing its thing again.
I have noticed that these two things tend to make the largest difference in performance of a VBA script. There is a website Optimizing VBA that goes through some other things you can do, but they may not be worth your time. There is more discussion on the subject on another question I answered: VBA - Code Execution is Extremely Slow

Related

How to make Autofill more efficient, or an alternative to Autofill

I'm currently working on a document that needs to autofill a selection of cells down an area that is changing, although it will regularly be upwards of 25000 or more rows. The cells that I am attempting to autofill downwards are filled with "complex" formulas, that are configured to work with autofill.
When I have more than 15000 rows, to run one instance of
Worksheets("sheet1").Range("A1:A4").AutoFill Destination:=Range("A1:A" & LastRow), Type:=xlFillDefault
this will take upwards of 20 minutes to completely execute this one line, so if I need to run this 5 times for an example, we're looking an estimated 100 minutes of run time for 5 lines of code.
I'm curious if there's a more efficient way to either use AutoFill, or execute the task I'm looking to achieve.
I haven't really found much that was helpful, I did change my range a few times to see if that increases or reduces times.
If I change LastRow to be equal to say, 50-1000 this line of code runs instantaneously. Once we creep above the 1000 rows, this starts to run incredibly slow.
Ideally, If I can find an additional way to run this that would significantly decrease my run times, that would be great.
There are some boilerplate code I use frequently to squeeze a better performance out of my VBA code:
Sub Test()
Application.EnableEvents = False
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
'Code here
....
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
Application.EnableEvents = True
End Sub
Application.ScreenUpdating = False makes your spreadsheet not jump around. Can't provide you with hard data here, but from my personal experience updating the screen slows down your macro quite significantly.
Application.Calculation controls how calculation is handled, and is defaulted to xlCalculationAutomatic. Under this default setting, all formula field gets updated when there is a change in value of a referenced cell. Setting it to xlCalculationManual before running your VBA, then back to xlCalculationAutomatic will ensure that calculations are only performed one time, instead of throughout your script when numbers are changing all the time.
Application.EnableEvents controls codes that is triggered by event (like saving, or activating a worksheet). Just in case, I set it to False.
Remember to set everything back to their default values at the end of your vba, or under your ErrorHandler section of your VBA.
Just FYI, having these two application settings changed makes it a harder to debug your code if you rely on looking at your spreadsheet to debug. Best to completely remove them during debugging, and add them back once you are ready to push to production.
Without your specific formula, it is hard to further optimize. There is one other way you may try that MAY speed things up.
Sub MyAutoFill()
My_Formula = "SUM(1,3)" 'Replace this with your complex formula, remember to escape your inverted commas
Worksheets("sheet1").Range("A1:A" & LastRow) = "=" & My_Formula
End Sub
The above code sets the values of a range to a string the begins with "=", which becomes an excel formula on the worksheet. This MAY be more efficient than autofill, try it out and report back!

How to refresh database data in Excel at regular intervals?

In an Excel spreadsheet/VBA script I'm making, I need to call data from a database, and refresh the values every 5 minutes. The program starts from the push of a button, and should run continuously until the user breaks the execution. I'm currently not sure how to make Excel/VBA 'wait' 5 minutes without pausing the spreadsheet and, ideally, without being computationally inefficient.
I've tried using the "Application.Wait" and "Sleep" functions, but both of those pause the spreadsheet during the 5 minute wait.
My current solution is to use a "While" loop with "DoEvents" inside it, as shown in the code below. This makes the program just run the "While" loop for 5 minutes, and it does not pause the spreadsheet thanks to "DoEvents". However, while the spreadsheet is usable, this is computationally inefficient, since the program execution isn't technically paused, it's just running the "While" loop continuously, and some of the slower computers that may end up using my program might be significantly slowed by this.
My current solution is as follows:
Sub MainProgram()
'dimension variables, open database connection, etc.
Do While 1 < 2 'ad infinitum
'get database data, write to spreadsheet, etc.
WasteTime()
Loop
End Sub
Sub WasteTime()
EndTime = Now + TimeSerial(0,5,0)
While Now < EndTime
DoEvents
Wend
End Sub
The problem with this, as mentioned above, is the computational inefficiency. CPU utilization is fairly high throughout the WasteTime loop. So I'm wondering, is there any way to pause the script without pausing the spreadsheet and without running the code continuously, thus burdening the CPU?
As BigBen mentions in comments Application.OnTime is the best option for this. It avoids the overhead you describe by scheduling a second macro to be called at a future time.
Below is an example. You can modify the wait time with the constant variable. These should be within the same Module (or change theCalculation macro to not be private).
Sub TheTimerMac()
'enter in timevalue (hour:Minute:Second)
Const DelayTime As String = "00:05:00"
Dim nextRunTime As Date
nextRunTime = Now + TimeValue(DelayTime)
'Schedules application to execute below macro at set time.
Application.OnTime nextRunTime, "TheCalculation"
End Sub
Private Sub TheCalculation()
'whatever you use for your calc here
Application.CalculateFull
'This will restart the timer portion.
Call TheTimerMac
End Sub

Does making some codes in the same line makes the macro faster in VBA?

I've tried every suggestion on this site to make my macro faster.
Halt calculations
Disable the screen updating
Disable status bar updating
Telling the Excel to ignore events
and so much more. Even in loops, I've tried many methods of making my macro smooth.
And I saw an article that I can use colon to make a multiple lines of codes into single line.
From:
Dim x as Integer
x = 1
If x = 0 Then
Exit Sub
End If
To:
Dim x as Integer: x = 1: If x = 0 Then Exit Sub
Does making some codes in the same line makes the macro faster?
No, writing the code on the same line does not make the code run faster.
Code can be slow because of inefficient coding techniques, like looping through all cells in a column, reading each cell, calculating it, and writing the result back to another cell in each step of the loop.
Writing that code in one line is possible, but it won't make the code run faster.
What WILL make the code run faster is reading the data range into an array, then looping over the array, writing the output of any calculation into another array and then finally writing the result array back to the spreadsheet as one write operation.
This is simply a different line break and does not affect execution time.
You already noted a couple of tricks you applied:
Application.ScreenUpdating = False
Application.DisplayAlerts = False
Application.Calculation = xlCalculationManual
Application.EnableEvents = False
Since you haven't posted full code and "Please optimize my code" is not a question, there's the following general tips to speed up Execution:
When referencing the same Object multiple times in a row, use With and End With instead. This is faster than specifying the full path to the object each time, since it prevents certain IO operations to access the right block in memory.
Use as little references to Worksheet / Range objects as possible, in general. A lot of times it's faster to use an Array than a Range. See Chip Pearson's article on this.
Looping is slow. Using native functions is faster. Make use of Autofilter instead of checking each cell, for example.
Do not use Copy and Paste, instead use the Destination parameter of the Copy method
Declare your objects as accurately as possible: Use Dim ws As Worksheet instead of Dim ws or Dim ws As Object.
Never use .Select and .Activate - See this Question
No, such changes does not boost Your code.
It also depends what Your macro do, but my case was that I needed to use sth similar to vlookup in my code, so at the first version I used ForEach loop and if statment - when I was to match 10 000 records with about 3k values it took about 15 minutes. So I decided to use dictionary (reference does not break acro on other machines) and it really boost my code. Now 20 k records with 6k values takes about 2 minutes.

Excel VBA Slow Calculation Loop Iterations

Not sure if this is a code-specific issue or not, so I will be general for now.
I have a somewhat complicated macro that begins by reading financial market data that is manually inputted by a user into a worksheet, and then proceeds to process that market data, generating the required market curves, etc., and then calculate the certain valuations of interest.
The process requires a lot of looping since there are thousands of instruments that need to be valued. However, I noticed that every now and then the macro will loop extremely slowly - on the order of about 2-3 seconds per iteration. When I have the Excel workbook up, I can see down at the bottom it is saying "Calcuating (4 Processors x% complete)".
To resolve the issue I have to manually force Excel to shut down; usually this fixes the problem and the next time I run the program it works fine.
I am running Windows 8 (not 8.1) and Excel 2013. I've heard that this combination is particularly prone to crashing/bugs (I've experienced this several times myself where Excel will take a very long time to process basic requests such as font formatting or will spontaneously crash for no apparent reason).
However, I'd like to ask the community to see if the problem is more universal/known.
Thanks!
As a general tip for creating fast excel macros: wherever prossible don't loop through cells, you will get much better performance using a with statement on a range object, or where you need to operate on the data in a more elaborate way try copying your range of data into a 2 dimensional array, looping through an array will be orders of magnitude faster than looping though cells in a worksheet, you can then dump the array back to the range.
Try application.visible = false in the beginning of your code. Then make sure to do application.visible = true at the end. Should help.
Try to change the cursor to xlBeam
It changes everything in terms of speed in Windows 8.1
Sub CurseurDefault(zz As Boolean)
If zz = True Then
Application.Cursor = xlDefault
'Call ShowCursor(True)
Else
Application.Cursor = xlIBeam
'Call ShowCursor(False)
End If
End Sub

How do I determine whether calculation was completed, or detect interrupted calculation?

I have a rather large workbook that takes a really long time to calculate. It used to be quite a challenge to get it to calculate all the way, since Excel is so eager to silently abort calculation if you so much as look at it.
To help alleviate the problem, I created some VBA code to initiate the the calculation, which is initiated by a form, and the result is that it is not quite as easy to interrupt the calculation process, but it is still possible. (I can easily do this by clicking the close X on the form, but I imagine there are other ways)
Rather than taking more steps to try and make it harder to interrupt calculation, I'd like to have the code detect whether calculation is complete, so it can notify the user rather than just blindly forging on into the rest of the steps in my code. So far, I can't find any way to do that.
I've seen references to Application.CalculationState, but the value is xlDone after I interrupt calculation, even if I interrupt the calculation after a few seconds (it normally takes around an hour).
I can't think of a way to do this by checking the value of cells, since I don't know which one is calculated last. I see that there is a way to mark cells as "dirty" but I haven't been able to find a way to check the dirtiness of a cell. And I don't know if that's even the right path to take, since I'd likely have to check every cell in every sheet.
The act of interrupting calculation does not raise an error, so my ON ERROR doesn't get triggered.
Is there anything I'm missing? Any ideas?
Any ideas?
I think the trick you need to implement (if you're application runs in Excel 2007 or later) is to handle this with the Application.AfterCalculate event, which is raised after both calculation is complete and there are no outstanding queries.
If you've never worked with events in VBA before, there is a good overview from cpearson.com.
The (MSDN) solution by Charles Williams above worked for me where I had 1000's of VLOOKUP's that neeeded to recalculate as the code was changing the lookup value because of an iteration loop. Results were skewed as calculations were not running to 100% completion.
At the beginning of my subroutine the code executes
Application.Calculation = xlManual
This eliminated unnecessary calculations by Excel until I was ready.
Now at the critical point the code executes
Application.Calculation = xlAutomatic
ThisWorkbook.ForceFullCalculation = True
Application.Calculate
Having forced Excel to perform a full calculation, the code could then saved the result and move onto the next iteration ... but before doing so
ThisWorkbook.ForceFullCalculation = False
Application.Calculation = xlManual
Remembering at the very end
Application.Calculation = xlAutomatic
I've never actually used it but I think this might work to prevent calculation from being interrupted.
Application.CalculationInterruptKey = xlNoKey
I think I'm hearing that you need a way to monitor whether each step within the calculations being performed was executed.
Assuming that you're not interested in re-engineering the workbook to use methods that are easier to track than spreadsheet calculations (such as volatile calculations within VBA or Pivot Tables), this may work for you:
Within VB, you can utilize .EnableCalculation and .Calculate to set an entire worksheet as "Dirty" (needing calculation) and then recalculate. The key difference between this and your current process is that we will perform these actions one worksheet at a time in manual mode. By initiating the calculations one worksheet at a time from within VBA, you will be able to perform additional intermediate actions that can be used to track how far you got in the calculation process.
Please note that this approach assumes a fairly linear workbook structure such that your workbook will produce the correct results if we first recalculate Sheet1, then Sheet2, Sheet3, and so on, in whatever order you wish. If your formula dependencies are more "spaghetti" than linear, this probably won't work for you. It also assumes you are working in Excel 2000 or later.
For example, you could write a VBA routine that accomplishes the following steps.
You will need to know your dependencies in order to know which calculations must come before others, and start with the worksheet in a "clean" state where no calculations are currently pending.
Step 1: Set the active sheet to the first worksheet where recalculation is needed
Step 2: Set the calculation mode to manual as follows:
Application.Calculation = xlCalculationManual
Step 3: "Dirty" the entire active sheet as follows:
With ActiveSheet
.EnableCalculation = False
.EnableCalculation = True
Step 4: Initiate a recalculation for this worksheet only (not the entire workbook) using:
.Calculate
End With
Note that if the calculation mode were set to automatic, Step 3 would initiate a re-calculation across the entire workbook. By using manual mode and With, we are constraining that calculation to the current sheet.
Now you have dirtied and re-calculated the first sheet (hurray!). Now, by embedding Steps 3 and 4 above into a For/Each or For/Next loop, you can repeat the process for each worksheet in your workbook. Again, make sure you know the order in which your worksheets need to be calculated (if an order is needed).
Now for the big finish - by creating a counter variable within your loop, you can track how far you got in the calculations by updating your counter variable value each time you complete a worksheet calculation. For example, after you recalculate a worksheet, you can set the counter value to current value + 1 and store the results either in a global variable (so that it will persist even after your VBA routine ends), or in a cell within your worksheet. That way, you can check this value later to see how many worksheets were updated before the calculations finished or were interrupted.
If you have relatively few worksheets in your workbooks, the same approach could be applied to one range at a time rather than a sheet.
I won't go into detail about how to construct a "counter", loops, or global variables here, but if needed, this information can be easily found using your favorite search engine. I would also highly recommend re-enabling automatic calculations once you are done as it is easy to forget that it's been set to manual mode.
I hope this works for you - for more information on calculation modes and recalculation, this is a helpful link:
http://msdn.microsoft.com/en-us/library/bb687891.aspx
Perhaps the following would work:
Do Until Application.CalculationState = xlDone
DoEvents
Loop
Can't say I've tested it, nor that I know how robust the functionality of Application.CalculationState really is to determine whether 'complete' calculation occurred, as opposed to something interrupting the process and flagging the calculation state as done.
Private sub SomeCodeThatGeneratesFormulas
Application.Calculation = xlCalculation.xlCalculationManual
'...Some formulas are copied here'
Application.OnTime DateTime.DateAdd ("s",.01,DateTime.Now), "Module1.CalculateFullRebuildAndSubsequentSteps" 'By using Application.OnTime, this method will be called in a way that locks the end-user out of providing inputs into Excel until the calculation itself is complete.
end sub
public sub CalculateFullRebuildAndSubsequentSteps
Application.CalculateFullRebuild
'...Do next steps, i.e. paste as values'
end sub
On the status bar, right hand side, it will say Calculating (N processors) X% (where N is the number of processors on your computer and X% is how much it has completed) when recalculating. If you don't see text there, it's not recalculating.
I'm using Office 2010, but it should be there in all versions. It's just kinda subtle so it's easy to miss.
Arrays in Excel can be a bit stupid. That is that in order to accomplish some tasks people avoid to use intermediate columns/rows to store (temporary) data, so arrays have to recalculate staff from the beginning every time, thus getting really slow. My Suggestion would be:
fix arrays to avoid multiple searches. Use hidden cells or even hidden sheets
Avoid using A:A and rather use A1:A1000 specially in excel 2007 or later
use formulas to equal zero or error (ex: NA()) while previous items aren't calculated, so you can clearly see if an operation is done at all.
some VBA could be used to inject formulas in place one step at a time, perform calculations, then proceed to next step, but this could mean lots of work...

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