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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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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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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