Run across a very strange issue that I am curious about. In Excel, I was doing a VLOOKUP to match contact names with a unique ID found in another database. Formula for example: =VLOOKUP(B2,Sheet2!A:B,2,TRUE), very basic. I used approx. match but, of course, some instances still returned #N/A. However, I did double checks with a quick control-F and found a number of instances returning NA when there was in fact a (exact) match. I was troubleshooting and trying a number of things but nothing was working. Many checks confirmed the cells were equal, there was nothing tricky like hidden characters, very peculiar. Anyway, on a whim I changed from approximate match to exact match and lo and behold it worked! The VLOOKUP was returning the correct value.
I'm trying to understand why this is. Obviously if you were requiring an exact match but there was only an approx. match it would return NA. But it doesn't make sense the other way around. An exact match should be returned when allowing even approx. matches! So just trying to understand what is going on behind the scene in VLOOKUP/Excel to make this phenomenon occur.
Appreciate any insight!
When working with approximate VLOOKUP, the key-column (always the 1st column of matrix-range) in the lookup-matrix should always be sorted in ascending order. The reasons for this is the following:
Imagine a key column with the values [2,3,10,4] in the given order. When the key '4' should be looked-up approximately, the function will start comparing the available keys in the column, beginning with '2'. After '3' was passed, '10' follows, which is already greater than the searched '4'. Consequently, the function stops searching and returns the target value of the previous key-row ('3') as an "approximation".
Now, given another example [10,2,3,4]. Here, approx. VLOOKUP will stop searching right after the first key comparison as '10' is greater than the searched '4'. Since no previous key-row is available, the returned value will be #N/A. However, an exact VLOOKUP would have found the matching key as it does not stop searching.
Besides key order, it is recommended to have all the key-values in the same format.
Hope this helps.
Related
Working in Excel 2019. In the same realm as one of my previous questions, I'm working with a database that I'm trying to look through via functions to get my values. The VLOOKUP tool worked well for going through the time-table to find the value I need, but it's not working when I'm trying to find RPM as the look-up value. Here's the gist of the data.
We have Time(sec, A:A in "PPT_156Data" sheet), RPM (B:B in same sheet), and Pressure (Bar, C:C in same sheet).
From the graph, you can see that we ramp to 8000RPM over the course of around 60 seconds, and then ramp down to 0RPM over the next 30. Test times WILL vary and rates WILL vary from pump-to-pump, as each one will give different data values based on the pump. That's why, say, 1000RPM will not be in the same spot every time.
I'm trying to find the RPM at 1000 intervals up to 8000 and report out the pressure at said intervals.
Here's what I tried so far, with imagery as well.
'Disregard if you see W25 for S25, I had just been trying multiple things
First, I attempted the same VLOOKUP code I had done for the time-table prior
=VLOOKUP(S25,PPT156_Data!B:C,2,TRUE) 'S25 being lookup value
This worked fine, UP UNTIL it hit a particular spot. For some reason, as soon as it tries to find an approximate match for 6663RPM, it faults out and gives incorrect data. From then on, all the way to 8000RPM, it will ONLY give the result of 0.139BAR. I have no clue why. Trying to find that value in the return array gives multiple results, but it's not like it's the ONLY value left.
So, I tried to do a wildcard for it with the following code
=VLOOKUP("*"&S25&"*",PPT156_Data!B:C,2,FALSE) 'Attempted both False and True states
Gave N/A for both of the values. Not sure if I'm entering in the wildcard incorrectly here. The decimal places that the RPM can go to ranges between 2-5 (hundredths to hundred-thousandths, IE 7000.00750)
I then thought maybe an Index Match would work.
=INDEX(PPT156_Data!B:C,MATCH(S25,PPT156_Data!B:B,-1),2)
Tried that in wildcard format too, returned nothing. So, I decided to see if I could even match a value for RPM with the following attempts
=MATCH(S25,PPT_Data156!B:B,-1)
This gave nothing. HOWEVER, when setting the match specification to 1, it gives the very last row in the data set. So, I decided to find a value in column B, and attempt to match with it exactly.
=MATCH(7000.07,PPT_Data156!B:B,0)
This also returned nothing. Even though, you can see in my images, that the value is ABSOLUTELY there. SIGFIG shows it's 7000.1 but trust me, it's 7000.07. So that sort of threw me for a loop. Figuring maybe there was a different error and grasping at straws, tried another Index Match formula, this time subtracting the lookup value in an attempt to get it extremely close and absolute value/min it
=INDEX(PPT156_Data!C:C,MATCH(MIN(ABS(PPT156_Data!B:B-S25)),ABS(PPT156_Data!B:B-S25),1))
I'm at a loss. I'm not sure if because the rate ramps up and down, thus not being in ascending order, is causing a problem? I can't change that. I am thinking I may need to create a macro for this in some way? Maybe a helper table? But I can't even FIND the match value to create a helper table. Any help at all would be VERY appreciative.
Thank you for your time looking at my post.
I am presuming that you want the first pressure reading when the RPM hits above each 1000 interval. I got to a solution but feels a bit complex.
=index(C:C,1/max(iferror(1/(row(B:B)*(B:B>E12)),Null)))
Breaking this down, we create a boolean array where the RPM hits above the interval
=B:B>E12
and then we multiple this by the array of the rows of column B
row(B:B)*(B:B>E12)
which gives us an array of the row numbers when the RPM is above E12 but also zero for all the ones that do not.
=iferror(1/(row(B:B)*(B:B>E12)),Null)
We then force an error with the zeros by dividing and replace with null. We get the max since we inverse the row numbers and then inverse again to get the row number back.
=index(C:C,1/max(iferror(1/(row(B:B)*(B:B>E12)),Null)))
[Excel working screenshot][1]
[1]: https://i.stack.imgur.com/uhcaX.png
Over the weekend, my work laptop did a restart and Microsoft gave me the perfect gift in Excel, it introduced the implicit intersection operator which has completely messed up my world, literally every formula has gone crazy.
I've checked every link I can and cannot work out how to correct even the most basic formula. I would like to ask about this one so I can at least make some progress forwards.
=FIND('Value Definitions'!C3,'User Interface'!K:K) was my formula that was worked forever.
The explanation of this formula is to flag all value definitions that have been used within text of all rows in the user interface column K.
When Excel asks me to correct the formula, it rewrites it as =FIND('Value Definitions'!C3,#'User Interface'!K:K).
This results in #VALUE rather than a number of where the first occurrence was found. If I remove the # then I get #SPILL!.
Just to reiterate the purpose of the formula, I identify which phrases exist in an interface that come from the value definitions worksheet, irrespective of the number value I get (character count of first occurence), I just want to identify that it exists at least once. Then I can use this flag to lookup all related value definitions to be included on the user interface.
Thanks for your help in advance.
Say, for instance, you type in
=INDEX('[ANOTHER FILE.xlsx]1'!$B$5:$Z$10,
MATCH($A5,'[ANOTHER FILE.xlsx]1'!$A$5:$A$10,0),
MATCH(B$3,'[ANOTHER FILE.xlsx]1'!$B$3:$Z$3,0)
)
Here, I'm worried that B3:Z3 and B5:Z10 are one row apart. Is this an acceptable setting?
In my opinion it is, because after all INDEX(MATCH) retrieves the corresponding row*column number in the matrix, so as long as you provide the correct row and column numbers, the corresponding correct number will be retrieved.
Yes, it is acceptable. The only thing you need to worry about is that the MATCH produces the correct number for the lookup you want to achieve. Where that number comes from is totally irrelevant.
I've adapted this solution from a couple of years ago:
=LOOKUP(2^15,FIND(Keywords,A2),Categories)
I use this for searching within a description field for keywords in a named list, in order to return a corresponding category from an adjacent named list.
However I do not understand the significance of 2^15. Can someone explain?
Also it's unclear in what order the search operates. If two keyword options were "check" and "deposit," and they were assigned to different categories, but both appeared in the same description field cell, how do I know which will be found first? Is it placement in the string, or order in the list?
2^15 is simply an arbitrarily large number, which lookup attempts to find - when it can't find it, it takes the next lowest number.
Effectively your formula looks at Keywords, and attempts to find the value in A2. For each word that actually matches A2, it provides a non-error message. Then out of the whole list, it attempts to find that line number in categories, resulting in many errors, and a single correct value. Lookup picks the value by using 2^15. Though this seems to be a weird way of doing it; it is likely a holdover of pre-2007, as Lookup is generally used now only for backwards compatibility purposes. Also using 1 instead of 2^15 worked for a couple of simple cases that I tried when writing this up.
this is my first post so i am sorry if this is confusing at all. I am trying to use a vLookup to run a comparative analysis between two reports. I am using a part number as a reference and trying to return the cost associated with the part from one of the two reports. So, the first issue that I encountered was due to the fact that some of the part numbers had letters in them and some didn't, so to be consistent I used the following code to clean up the part numbers:
IFERROR(VALUE(F11&C11), F11&C11)
where F11 and C11 are two components of the part number that needed to be concatenated to generate the full number. Now, the vLookup will not return anything except for #N/A for a few of the part numbers that are actually in the sheet. All of the part numbers are formatted the same for the 892 part numbers that I am searching for but get a returned value on 571 of the 892 part numbers but of the remaining 321 part numbers that did not have a return, about a third actually exist in my sheet. Lastly and for example, part number 110874402 exists in both sheets but gets a #N/A from the vLookup. When I copy the value from one sheet and search it in the other sheet using Ctrl + F, I get the following:
(I have an image to show but apparently can't post it without a reputation of 10 or more...oops)
The highlighted cell shows that the value exists but Excel can't find it. Does anyone have any ideas why this is or what I could be doing differently? I've been having this issue for a few months now on separate projects and haven't found any resolution.
Thanks in advance,
try =VLOOKUP("*"&TRIM(F569)&"*", BOBJ!$D$3:$P$2237, 7, FALSE) - I have a feeling spaces may have crept around the part numbers, which means that the exact match will not work.
The TRIM takes the spaces from the cell you are looking at, and the "*"'s will allow a wildcard search - note that this also means that CAT would also match CAT1, but if it produces results where there were none before, it gives you something to check for.