I am trying to make a simple savings system and i have already set a simple function to calculate interest. The problem is the interest rate formula. Once the app will be deployed, the formula cannot be changed anymore. My plan is to store my formula in a database and retrive the formula everytime the interest function is called but the function treats the formula as string.
Is there any way to change how a function would work during runtime?
Related
I have a table in Excel that has column heading names (e.g. data_type1, data_type2, etc.). The data in this table changes based on parameters entered on another sheet, and they are pulled to charts which update dynamically.
As a convenience to a user who might be using this sheet I have added a 'user specified function' (non-vba) which also plots to one of the charts. By user specified function I mean I have three cells with dropdown lists. Two correspond to the table headings and one has a short list of operations that can be applied between the two selected data types (e.g. a user might select 'dataype1', '+', 'datatype2' which would produce a sum of the two in the final column of my table).
The user specified function is achieved by defining a named 'range/function' to match the drop downs with their respective column headers and then calls evaluate. See below:
=EVALUATE("="&ADDRESS(ROW('Raw Data'!XFD5),MATCH(user_in1,'Raw Data'!$A$4:$AF$4,0)) & user_operation & ADDRESS(ROW('Raw Data'!XFD5),MATCH(user_in2,'Raw Data'!$A$4:$AF$4,0)))
I name this 'user1_result' and then enter =user1_result in the final column of my table. This approach is nice because it calculates much faster than doing the same thing through building a UDF in VBA and then applying that UDF to every cell in a fairly long column.
Now here is my hangup, this works fine initially, but if the user makes a parameter change that affects one or both of the selected datatypes, the user specified column does not recalculate on-the-fly with the updated data. If the user re-toggles any of the dropdowns the data does recalculate. I am speculating this is from one of two things:
1) Excel does not recognize that a precedent of 'user1_result' has changed, and so for efficiency sake doesn't bother to recompute the column;
2) The 'Evaluate' function used in the named definition of 'user1_result' is not checked for updating, because it's not a normal function (doesn't show up through intellisense if you try to just add that to a cell).
So I am looking for some either confirmation or refutation of these speculations. In the case of confirmation I am hoping to get some advice on how to force the user specified column to update if its precedents change.
One solution is to have VBA do this checking for me and force the computation, but I would like to leave that as a last resort. So, non-VBA solutions preferred.
For posterity I'll answer the above question based on Mat'sMug's feedback:
Regarding the cause of the problem:
The reason the user specified column does not update is because the 'Evaluate' portion of the 'user1_result' named formula is intended to be used at the application level and not as a worksheet function. Because of this, Excel doesn't bother checking to see if its precedents change and ignores it for recalculation.
The problem's solution:
It was suggested to use VBA to watch for worksheet_change events, however, my problem requires that I do NOT use VBA. So, an alternative workaround that forces Excel to check precedents and recalculate the user specified function uses two steps. This functions as a pseudo worksheet_change stand-in.
First, I use a helper cell that performs a countif with an arbitrary counting condition. I don't need it to change, I just need it to share precedents with the inputs of 'user1_result'. So I have it count the number of cells in the first row of data that are larger than some constant:
=COUNTIF(A5:AK5,">100000")
The result of this computation doesn't matter, but in my case my data have small values and so this returns 0 always.
Second, I use a condition for the computation in the user specified column (the last column in my data table).
=IF($AO$1=$AO$1,user1_result)
Now, anytime my data table updates, the final column using the named function recomputes. Simple, and if using macros is not viable (for example due to a client/user's security concerns), this can sort of substitute for a worksheet change event.
I hope somebody out there gets use from this!
I have a excel sheet that display's price on certain items in a column by looking up amazon API using excel vba. The price of may change overtime. So I am trying to display the difference in prices each time i run my macro, in a cell adjacent to the cell that displays price.
But I am not sure how to achieve this. Can any body guide me on how to achieve this?
This is just a sample, it must be adapted to your schema and data layout. Say the prices are stored in column A from A1 to A100. Say you already have a macro called RefreshData() that updates column A. In B1 enter:
=C1-A1
and copy down. This macro store the current values in column C before refreshing the data:
Sub DoUpdate()
Range("A1:A100").Copy Range("C1")
Call RefreshData
End Sub
Column B will display the price difference.
Something like this?
Let's say your data are in a range A2:A10
Dim rng as Range
Set rng = Range("A2:A10")
rng.Offset(0,1).Value = rng.Value
Run this before you run your original macro to store the values in an adjacent column before the values change. You may need to make the range dynamic, depending on your needs.
Without seeing you code, I cannot give a detailed answer. However, I ran across a similar problem once, not using Amazon API though, but a sharepoint connection.
If the amazon api is somewhat similar to the sharepoint stuff, I guess it refreshes cells when you click "update", or run the update sub. In that case you will have to either create an array to store the old prices in vba (very slow process), and then write them to your table, or create a separate tab where you store the item-lastPrice combination.
I ended up storing not only current price but all prices and the date/time of the price, to be able to see change over time.
For the copying of data itself using VBA, either of the above methods should work. In my initial code I used vba loops :-p, but copying using excel functionality is much faster.
I have a very simple task. I have two datsets. The first is a single value that has returned me a number of calls that has been made. The second is a list of targets. I want to be able to divide the first number of calls by its call target in order to calculate the total %.
The lookups of these are dependant on the criteria that is selected in the report itself. I know it's possible to do inside SQL its just a huge pain in the ass. I want to be able to calculate two fields and I thought something so simple would be a breeze for SSRS but apparently not. So the error i get is:
*The expression used for the calculated field'=fields!DMCP.Value / FIRST(Fields!DMCTarget.Value,"AllTargets")' includes an aggregate,rownumber,runningvalue, previous or lookup function. aggregate,rownumber,runningvalue, previous and lookup functions cannot be used in calculated field expressions.*
I can take the first function out but it doesn't help me. It says it can only calculate in the same dataset, problem is these values can never co-exist in the same dataset. Anything I can do????
Thanks in advance
Data tables in Excel are really nice to see how numbers would evolve if one of your input changes. However:
they're (very) slow
the variable you edit is not dynamic; i.e. changing the row or column input cell to =INDIRECT(<dynamic address>) works but doesn't update if the dynamic adress changes.
they force you to use an annoying structure
the variable needs to be in the same sheet as the table
Because I want to do a lot of them, point 1 and 2 make it very impractical to work with data tables. Is there any way to make a function that does this in VBA? I tried a UDF that changes the variable's value (e.g. =whatif(<hypothetical output>, <variable cell>, <variable hypothetical value>), but that's not allowed in VBA (see How to prevent VBA function from re-executing inside the code).
I am quite sure you can achieve your goals using subs rather than UDFs. The concept is to, basically, treat the worksheet like one huge function:
the sub sets up a group of input cells
the sub allows the worksheet to calculate
the sub monitors the output cell(s)
If the goal is some kind of non-linear analysis (like sensitivity analysis), the sub compares successive runs. If the goal is some kind of optimization, the sub drives the inputs to achieve a result. If the goal is some kind of statistical analysis or modelling, the sub can drive a Monti Carlo.
I am trying to find the best moving average and stumbled upon a problem.
I can create cells with content like B233:B253 based on a n. However, I am unable to paste this value to the AVG() function, which sees the value as a string.
Is there any kind of eval() function?
VBA is out of the game as I am going to use MS Solver.
there is a type of eval function - INDIRECT
Example
put 3 values in column A
put A1:A3 in B1
=AVERAGE(INDIRECT(B1)) will give you the average of cells A1:A3