I have a very long formula that churns out the correct answer when it is just focussed on calculating one row.
I want to turn this into an array that will sum over multiple rows, however as soon as i turn the formula into an array it then gives an incorrect value... and i don't know why! For some reason it seems to do an extra multiplication when i put it into an array, i believe anyway.
Original working formula on single row:
=(IFERROR(.........
+12.5*$C15), ....)
Not working array:
{=SUM(IFERROR(.........
+12.5*$C15:$C16), ....)
When C15 is 0.5, the array returns a value that is 6.25 too low
When C15 is 1, the array returns a value that is 12.5 too low
When C15 is 1, the array returns a value that is 25 too low
So it is most definitely something to do with the 12.5 but i don't understand why turning it into an array makes it return a value too low.
Based on the duplicate question found here: https://stackoverflow.com/questions/42025870/excel-array-formula-complicated?noredirect=1
You do not need the IFERROR:
The CSE array formula:
=SUM(IF(ISNUMBER(SEARCH("S",B2:B3,1), 1, 2))
Remove the quotes around the numbers, with quotes they are strings and SUM will ignore them.
The ISNUMBER takes the place of the IFERROR.
This is an array formula and needs to be confirmed with Ctrl+Shift+Enter.
If done correctly then Excel will put {} around the formula.
Related
I have a 2D array PointAndTangent of dimension 8500 x 5. The data is row-wise with 8500 data rows and 5 data values for each row. I need to extract the row index of an element in 4th column when this condition is met, for any s:
abs(PointAndTangent[:,3] - s) <= 0.005
I just need the row index of the first match for the above condition. I tried using the following:
index = np.all([[abs(s - PointAndTangent[:, 3])<= 0.005], [abs(s - PointAndTangent[:, 3]) <= 0.005]], axis=0)
i = int(np.where(np.squeeze(index))[0])
which doesn't work. I get the follwing error:
i = int(np.where(np.squeeze(index))[0])
TypeError: only size-1 arrays can be converted to Python scalars
I am not so proficient with NumPy in Python. Any suggestions would be great. I am trying to avoid using for loop as this is small part of a huge simulation that I am trying.
Thanks!
Possible Solution
I used the following
idx = (np.abs(PointAndTangent[:,3] - s)).argmin()
It seems to work. It returns the row index of the nearest value to s in the 4th column.
You were almost there. np.where is one of the most abused functions in numpy. Half the time, you really want np.nonzero, and the other half, you want to use the boolean mask directly. In your case, you want np.flatnonzero or np.argmax:
mask = abs(PointAndTangent[:,3] - s) <= 0.005
mask is a 1D array with ones where the condition is met, and zeros elsewhere. You can get the indices of all the ones with flatnonzero and select the first one:
index = np.flatnonzero(mask)[0]
Alternatively, you can select the first one directly with argmax:
index = np.argmax(mask)
The solutions behave differently in the case when there are no rows meeting your condition. Three former does indexing, so will raise an error. The latter will return zero, which can also be a real result.
Both can be written as a one-liner by replacing mask with the expression that was assigned to it.
So I m trying to find some alternative to sumifs in excel where each condition needs to be checked in a 2D range instead of a 1D range.
For example, in the below table I want the sum of values in column V for rows where A12 ("IJ") is present in range A2:C8 (P), B12 ("NM") is present in the range D2:F8 (S) and C12 ("XX") is present in range G2:I8 (A)
I am trying to find a solution involving an array-based formula (without VBA).
Like for example in the below-given formulas,
SUMPRODUCT((B2:B8'=A12)*J2:J8) will give an array-based calculation as follows
SUMPRODUCT({TRUE;FALSE;TRUE;FALSE;FALSE;TRUE;FALSE}*{22;79;45;67;43;72;52})
= SUMPRODUCT({22;0;45;0;0;72;0})
=139
It is easy when there is only one condition needs to be checked but like sumifs, I intend to check multiple conditions, but as soon as I add other conditions, the array becomes multidimensional and gives the wrong answer.
Example:
SUMPRODUCT((A2:C8=A12)*(D2:F8=B12)*J2:J8) breaks down to
=SUMPRODUCT(
{FALSE,TRUE,FALSE;FALSE,FALSE,FALSE;FALSE,TRUE,FALSE;FALSE,FALSE,FALSE;FALSE,FALSE,FALSE;FALSE,TRUE,FALSE;FALSE,FALSE,FALSE}*
{TRUE,FALSE,FALSE;FALSE,FALSE,FALSE;TRUE,FALSE,FALSE;FALSE,FALSE,FALSE;FALSE,FALSE,FALSE;TRUE,FALSE,FALSE;FALSE,FALSE,FALSE}
*J2:J8)
in the background what is happening is (example for 3rd row)
SUMPRODUCT( ({FALSE, TRUE ,FALSE} * {TRUE,FALSE,FALSE}) * 45 )
= SUMPRODUCT({FALSE,FALSE,FALSE} *45 )
=0
SUMPRODUCT(({FALSE,TRUE ,FALSE} + {TRUE,FALSE,FALSE}) * 45 )
= SUMPRODUCT({TRUE,TRUE,FALSE} *45 )
= 90
#expected answer =45
Can someone help me understand where I am going wrong or what I am missing?
If there is any other way then suggestions are always welcome.
Please note this is a dummy data actual data is very big for each header (P,S,A) there are values in 10 columns respectively and the number of rows is also very large.
Try this...
=SUMPRODUCT( ((A2:A8=A12)+(B2:B8=A12)+(C2:C8=A12)) * ((D2:D8=B12)+(E2:E8=B12)+(F2:F8=B12)) * ((G2:G8=C12)+(H2:H8=C12)+(I2:I8=C12)) * J2:J8 )
For SUMPRODUCT to work, the shape of the Boolean array needs to match the shape of the array you wish to conditionally sum.
J2:J8 is seven rows tall by one column wide.
The above formula creates an array of 1s and 0s from your three criteria ranges and shapes it into seven rows tall by one column wide.
At that point, SUMPRODUCT can do it's normal thing because the criteria array matches the dimension of the sum array J2:J8.
Recently in an interview i was asked this question.
Given:
a + or - b = 40 // You can choose any one operator + or -
[list of any numbers in an array]
Explain how will you choose numbers for A and B from an given array to make the result 40 ?
My Answer:
Consider 1st element of array as A, now iterate through array from start to find possible values of B while this process fetch each element from array, sum up with A and compare it with 40.
But he was not happy.
Any other approaches ?
Sorting would definitely help you get the solution your interviewer has looked for:
First, sort the array. Should take about O(nlogn).
Now put 2 pointers, i and j. i starts at the beginning of the array, and j starts at the end.
Compare the 2 values (that i and j point to) to 40. If the result is bigger than 40, j moves to the left. If the result is smaller than 40, i moves to the right. You will keep doing this until having two values with the sum of 40.
If not found yet, do the same thing the other way around, for the subtraction of both values, to get 40.
The whole solution takes only O(nlogn) and is very elegant.
Good Luck!
We have a project on a certain math subject and I am done with the computations and it works just fine. So the task is, let's say you have a system of linear equations of certain number of unknowns, you input the number of unknowns, and fill in the values, and using matrix computations, find all the value of unknowns.
To make this short, I already finished the "find the value of unknowns" along with the computation, I checked it, and it seems fine. I can put 6 as the number of unknowns and it automatically computes the inverse of a 6x6 matrix and it will return the 6 unknown values using Index INDIVIDUALLY.
(Note: We aren't allowed to use VBA or Macros since we haven't discussed that yet.
The problem is, I don't know how to automatically fill a RANGE of cells with a VALUE or A FORMULA based on a SINGLE cell value.
For example, In cell A1, I will input 5 (which indicates the number of unknowns), then upon inputting this and hitting enter, let's say a range of cells A2 to A6 (which is 5 cells) will be automatically filled with incremented letters, like for A2 -> A ; A3 -> B ; ... A6 -> E, of which these letters indicate the 5 unknowns.
PROBLEM 2.
Another follow up question, let's say I input again 5, which again stands for the number of missing values/unknowns, in A1, besides the column of the variables A,B,C,D,E (5 unknowns), I want to automatically fill column B respectively with values from an array.
This is just the same with my first problem but this time, instead of incremented letters, it would be Incremented Index function.
For example: I input 5
*Column A will automatically be filled with the variables/letters
*Column B will automatically be filled with the values from an array that's computed using a formula but is not shown independently on cells.
I already have the formula
INDEX(Formula I created, Row number of the answer from the Formula I created , Column number of the answer from the formula I created)
The answers from the formula I made myself is also an array, an "n" rows and 1 column array. If I put the Index formula on a SINGLE cell, it returns specified row number value from the array that resulted in the computation from my formula
What I want is for example, for 5 unknowns
**A | B**
1|.......5..........................
2|.......A..............Some Value 1
3|.......B..............Some Value 2
4|.......C..............Some Value 3
5|.......D..............Some Value 4
6|.......E..............Some Value 5
Wherein the "Some Value" is the Arrayed Answer from my formula and the "1,2,3,4,5" specifies the row number from that arrayed answer.
This is upon inputting the matrix values, inputting the number of unknowns "n" in A1, and automatically filling a range of cells A2 to A"n" with letters A up to what letter "n" corresponds, and automatically filling a range of Cells B2 to B"n" with my formula but with incremented row number for every row in the Index(Formula, Row number , Column number) function.
Note: I hope there's a way to do this using excel functions only since we haven't discussed VBA or Macros yet so we can't use those, and even If we can, I have no knowledge for that. haha. :D
THANK YOU THANK YOU THANK YOU SO MUCH IN ADVANCED! Cheers. :D
Here's a formula for column A:A (write this in cell A2) and drag down:
=IF(ROW()-1<=$A$1,CHAR(ROW()+63),"")
Can anyone tell me if there is a way (in MATLAB) to check whether a certain value is equal to any of the values stored within another array?
The way I intend to use it is to check whether an element index in one matrix is equal to the values stored in another array (where the stored values are the indices of the elements which meet a certain criteria).
So, if the indices of the elements which meet the criteria are stored in the matrix below:
criteriacheck = [3 5 6 8 20];
Going through the main array (called array) and checking if the index matches:
for i = 1:numel(array)
if i == 'Any value stored in criteriacheck'
%# "Do this"
end
end
Does anyone have an idea of how I might go about this?
The excellent answer previously given by #woodchips applies here as well:
Many ways to do this. ismember is the first that comes to mind, since it is a set membership action you wish to take. Thus
X = primes(20);
ismember([15 17],X)
ans =
0 1
Since 15 is not prime, but 17 is, ismember has done its job well here.
Of course, find (or any) will also work. But these are not vectorized in the sense that ismember was. We can test to see if 15 is in the set represented by X, but to test both of those numbers will take a loop, or successive tests.
~isempty(find(X == 15))
~isempty(find(X == 17))
or,
any(X == 15)
any(X == 17)
Finally, I would point out that tests for exact values are dangerous if the numbers may be true floats. Tests against integer values as I have shown are easy. But tests against floating point numbers should usually employ a tolerance.
tol = 10*eps;
any(abs(X - 3.1415926535897932384) <= tol)
you could use the find command
if (~isempty(find(criteriacheck == i)))
% do something
end
Note: Although this answer doesn't address the question in the title, it does address a more fundamental issue with how you are designing your for loop (the solution of which negates having to do what you are asking in the title). ;)
Based on the for loop you've written, your array criteriacheck appears to be a set of indices into array, and for each of these indexed elements you want to do some computation. If this is so, here's an alternative way for you to design your for loop:
for i = criteriacheck
%# Do something with array(i)
end
This will loop over all the values in criteriacheck, setting i to each subsequent value (i.e. 3, 5, 6, 8, and 20 in your example). This is more compact and efficient than looping over each element of array and checking if the index is in criteriacheck.
NOTE: As Jonas points out, you want to make sure criteriacheck is a row vector for the for loop to function properly. You can form any matrix into a row vector by following it with the (:)' syntax, which reshapes it into a column vector and then transposes it into a row vector:
for i = criteriacheck(:)'
...
The original question "Can anyone tell me if there is a way (in MATLAB) to check whether a certain value is equal to any of the values stored within another array?" can be solved without any loop.
Just use the setdiff function.
I think the INTERSECT function is what you are looking for.
C = intersect(A,B) returns the values common to both A and B. The
values of C are in sorted order.
http://www.mathworks.de/de/help/matlab/ref/intersect.html
The question if i == 'Any value stored in criteriacheck can also be answered this way if you consider i a trivial matrix. However, you are proably better off with any(i==criteriacheck)