Molecular Weights 10

I wouldn’t normally publish a post on such an esoteric topic as this. However, since the idea for it came as a result of a challenge posed by the venerable David Hager, I felt that I could not resist.

And that challenge was as follows: given a list of chemical elements and their respective atomic weights, a formula to determine the weight for a given molecule.

It goes without saying that there are numerous quick and easy online applications which will perform such a calculation. Nevertheless, and however unlikely it may seem, there is still a small probability that this post will reach one or more of the tiny minority who have a practical need for such calculations to be performed within Excel (and, in addition, perhaps without recourse to VBA).

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Shortest Formula Challenge #6: Results and Discussion Reply

A couple of weeks ago I set readers the challenge which can be found here.

Once again, some truly excellent responses and a noticeably collaborative attempt towards obtaining our final, minimal-length solution. So many thanks to all who contributed: Alex, John Jairo, Lori, Snakehips and Will!

And that solution, at 108 characters, is:

=LOOKUP(,0/FREQUENCY(0,2^-(LEN(Q5:Q77)>4)/MMULT(SUMIF(U3:U28,MID(Q5:Q77,COLUMN(A1:G1),1),V3),1^V3:V9)),Q5:Q6)

How does it work?

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Redimensioning 18

Readers who have read some of my earlier posts will be familiar with the concept of “redimensioning” an array.

This is an extremely useful and important technique, which, in its basic form, allows us to take a two-dimensional array and convert it into one of just a single dimension, whilst of course retaining the elements within that array.

Such an approach is necessary if we wish to further manipulate the entries of some two-dimensional array. For example, we might be in a position in which, for whatever reason, we need to pass each of the entries in a two-dimensional array to an array of one or more parameters for further processing. However, since the evaluation of the resulting multi-dimensional “matrix” is not within Excel’s capabilities, we are obliged to first transform the original array to one of a single dimension.

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Simultaneous Locating of First and Last Numbers in a String 23

I was initially debating whether to give this post a more pragmatic title, such as “Extracting Phone Numbers from a String”, that being one of the more common practical applications for the techniques outlined here.

However, the extraction of phone numbers (I’m referring here to that type which employs some form of delimiter, e.g. 1-800-12345, and not that which comprises a non-delimited numerical string, e.g. 180012345, there existing already well-documented formula techniques for the extraction of the latter – although of course the set-up given here will work for those as well) is certainly not the only use for this method, and so, in the end, I chose to go with a less restrictive, more theoretical title.

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Extracting Numbers of Set Length Only from Alphanumeric Strings 18

In this post I would like to present a solution to the practical problem of extracting a number of defined length from an alphanumeric string which may contain several numbers of varied lengths.

Indeed, the inspiration behind this post is in part derived from having personally witnessed many such requests on the various Excel forums, most of which involve the extraction of e.g. an account number of fixed length, 6 digits, say, from a longish string containing many other numbers.

As an example, given the following string:

20/04/15 - VAT Reg: 1234567: Please send 123456 against Order #98765, Customer Code A123XY, £125.00

we may wish to extract the one occurrence of a 6-digit number (123456) from that string.

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Advanced Formula Challenge #11: Results and Discussion 11

Last week I set readers the challenge which can be found here.

Good results for this one: six answers received, six correct answers received – from Oscar, Daniel, diondan1, Bill, Ikkeman and Calvin. Plus one (unverifiable, though no doubt correct!) Google Sheets solution from Isai, as usual. 🙂

So congratulations to all of the above!

The majority of those solutions adopted a strategy of comparing the characters from two sets of arrays derived using MID over an array of start_num parameters, though a couple of solvers (Bill and Calvin) decided to first derive the ASCII codes for these characters and instead use these as the basis for the comparison.

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Advanced Formula Challenge #9: Results and Discussion Reply

Last week I set readers the challenge which can be found here.

One correct solution received, courtesy of Lori, who not only presented a fine construction for working in Excel 2010 and earlier, but also a 2013 version, which had the added benefit of taking advantage of some of the new (and evidently very useful) features of that version to noticeably abridge the required set-up. So many thanks to Lori for sharing this knowledge and also congratulations on an excellent solution to a particularly complex challenge!

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Extracting numbers from a string 4: All numbers to a single cell 2

This is the fourth in a series of discussions on the techniques available for extracting numbers from an alphanumeric string.

In the first instalment in this series (which can be found here) I looked at extracting consecutive numbers which appear at the start of the string, e.g. 123ABC456.

In the second instalment (here) I looked at extracting consecutive numbers which appear at the end of the string, e.g. 123ABC456.

In the third instalment (here) I looked at extracting all numbers from a string where each of those numbers was to be returned to a separate cell. For example, given the string 81;8.75>@5279@4.=45>A?A; we extracted 81, 8.75, 5279, 4 and 45 into individual cells.

In this post I will look at a technique for extracting all numbers from a string, but where those numbers are to be returned as a single number in a single cell.

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Advanced Formula Challenge #8: Results and Discussion 2

Last week I set readers the challenge which can be found here.

At the time of writing (Saturday morning, UK time; apologies if anyone has submitted something after that date), two correct solutions received (or three if you count non-Excel-based ones: as he has done for most of the recent challenges, Isai Alvarado produced a solution applicable to Google Sheets, which, as usual, I am unable to verify! So I’m taking your word for it that it’s perfectly correct, Isai! 🙂 ).

The two correct entries came courtesy of Snakehips, who gave a rather lengthy but perfectly correct solution, and John Jairo V, who improved upon his earlier attempt by producing a solution which, in essence, used a similar approach to Snakehips’ but which made use of some very nice technique involving MMULT to considerably abbreviate the required construction. Great work, John!

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Extracting numbers from a string 3: All numbers to individual cells 28

This is the third in a series of discussions on the techniques available for extracting numbers from an alphanumeric string.

In the first instalment in this series (which can be found here) I looked at extracting consecutive numbers which appear at the start of the string, e.g. 123ABC456.

In the second instalment (here) I looked at extracting consecutive numbers which appear at the end of the string, e.g. 123ABC456.

In this post I will demonstrate a technique for extracting all numbers from a string where:

  • The string in question consists of a mixture of numbers, letters and special characters
  • The numbers may appear anywhere within that string
  • Decimals within the string are to be returned as such
  • The desired result is to have all numbers returned to separate cells

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Extracting numbers from a string 2: Consecutive numbers at end 3

This is the second in a series of discussions on the techniques available for extracting numbers from an alphanumeric string. In the first instalment in this series (which can be found here) I looked at extracting consecutive numbers which appear at the start of the string, e.g. 123ABC456.

In this post I will concentrate on techniques for extracting numbers from a string where:

  • The numbers are consecutive
  • The consecutive string of numbers is found at the very end of the string
  • The desired result is to have those consecutive numbers returned to a single cell

As previously, for each of the given solutions, we need to test its soundness in two separate cases: firstly, where there are no numbers elsewhere in the string, e.g. ABC456 and secondly, where there are some numbers elsewhere in the string, either at the start, e.g. 123ABC456, or in the middle, e.g. ABC123DEF456.

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Extracting numbers from a string 1: Consecutive numbers at start 8

This is the first in a series of discussions on the techniques available for extracting numbers from an alphanumeric string. Since we often have many different solutions at our disposable for such tasks, I will attempt to present what I feel are the principal candidates and, for each of these set-ups, discuss the merits and potential drawbacks inherent in each.

In the next instalment in this series I shall look at extracting consecutive numbers which appear at the end of the string, e.g. ABC123. In later posts I will deal with cases in which the desired numbers to be extracted are interspersed within the string in groups of one or more, e.g. ABC12DE345-FG6H789, in which case we may be interested in extracting either the number 123456789 into a single cell or each of 12, 345, 6 and 789 into four separate cells.

I shall also consider in future posts cases in which there may be several numbers within a string, though from which we wish to extract perhaps only one (or more) of these numbers, and for which our choice of extraction is based upon one or more criteria. For example, given a string of the form X12-X34-X56-X78-X90 we may wish to develop a technique which extracts the number immediately preceding the fourth occurrence of a hyphen within that string.

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Advanced Formula Challenge #7: Results and Discussion 1

Last week I set readers the challenge which can be found here.

This is a trickier problem than it at first appears, and indeed there are several pitfalls which prevent us from using more “standard” techniques to arrive at a solution.

Perhaps the two main (hidden) obstacles, which were not immediately obvious from the examples I gave, are, firstly, the fact that we are prevented from using a construction involving a SEARCH-approach (e.g. by locating occurrences of each substring of the four types *????*, †????*, *????† and †????†, as John Jairo V attempted), since this of course presumes that there is only one occurrence of each of those substring types within our string, a presumption which cannot be made.

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Converting from base 10 to base x Reply

This is a formula-based solution which, given a positive number in base 10, converts that number into its equivalent form for another, given positive base.

Convert from base 10 to base x

So, given a base-10 value to be converted in A2, and the base to which we wish to convert this value in B2, the required output is generated in C2. Cell D2 contains a “back-check” which re-converts the value in C2 to base 10.

The formula in C2 is:

=SUMPRODUCT(MOD(FLOOR(A2/B2^(ROW(INDIRECT("1:20"))-1),1),B2)*10^(ROW(INDIRECT("1:20"))-1))

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1/17 and other pandigitals 9

A slightly light-hearted post this, as you may have guessed from the title, though readers might find it moderately interesting, and hopefully some may even contribute to my rather esoteric collection of pandigital numbers in Excel.

This began as a result of seeing (I don’t recall where now, unfortunately) an alternative version of the tried-and-tested construction for returning a number from the end of a mixed string. For example, given the following in A1:

ABCDEF123456

the now-ubiquitous solution:

=0+MID(A1,MIN(FIND({0,1,2,3,4,5,6,7,8,9},A1&"0123456789")),LEN(A1))

will correctly return 123456.

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List of unique entries from column of space-separated strings 3

Given the list below in A1:A10, we may wish to create a list of unique, single words from that list, as per column B here.

Unique From Space Separated

We can do this with the following set-up: More…

Advanced Formula Challenge #2: Results and Discussion 3

Last week I set readers the challenge which can be found here.

Three solutions were offered, two of which from the same person, and both of which were correct! So many congratulations to Bill on successfully solving what was quite a complex challenge!

Indeed, as Ben Schwartz pointed out, this challenge appears to have been set previously on the internet, and seems to have been only partially solved on those occasions. In any case, thanks also to Ben for his suggestion, which he confesses was cobbled together from those previous solutions he found, and which worked in all but a few exceptional cases.

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Advanced Formula Challenge #1: Results and Discussion 4

Last Sunday I set a challenge to readers to come up with a solution to the problem here.

Even though this site’s only been up for one week, I’m quite happy to have received the single solution that I did, even more so since that solution was a correct one, from John Jairo Vergara Domìnguez, whose offering you can see if you scroll down to the bottom of that link. Thanks again, John, and well done!

As excellent as John’s solution was, it would still require a little tweaking to work for other ranges (part of its construction is dependent on the array in question being in certain columns within the worksheet) and, in any case, I would now like to present the solution that I developed for this problem.

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