can I do this with the standard SQL or I need to create a function for the following problem?
I have 14 columns, which represent 2 properties of 7 consecutive objects (the order from 1 to 7 is important), so
table.object1prop1, ...,table.object1prop7,table.objects2prop2, ..., table.objects2prop7.
I need compute the minimum value of the property 2 of the 7 objects that have smaller values than a specific threshold for property 1.
The values of the property 1 of the 7 objects take values on a ascending arithmetic scale. So property 1 of the object 1 will ever be smaller than property 2 of the objects 1.
Thanks in advance for any clue!
This would be easier if the data were normalized. (Hint, any time you find a column name with a number in it, you are looking at a big red flag that the schema is not in 3rd normal form.) With the table as you describe, it will take a fair amount of code, but the greatest() and least() functions might be your best friends.
http://www.postgresql.org/docs/current/interactive/functions-conditional.html#FUNCTIONS-GREATEST-LEAST
If I had to write code for this, I would probably feed the values into a CTE and work from there.
Related
On one sheet, I have account code and in the cell next to it, I need to look up the account code on the next sheet to average the cost excluding those cells that are zero in col. b from the average calculation.
The answer for London should be: £496.33 but having tried various sumifs / countifs I cannot get it to work.
You probably need COUNTIFS which -- similar to the SUMIFS you are already using -- allows to define multiple critera and ranges.
So, if the column R contains the values, you want to build the average upon, and the column H in the respective row must equal $B$28 to be included in the sum, the respective COUNTIFS looks as follows
=SUMIFS('ESL Info'!$R:$R,'ESL Info'!H:H,$B$28)/COUNTIFS('ESL Info'!$H:$H,$B$28, 'ESL Info'!$R:$R, "<>0")
ie additionally to the value in the H-column to equal B28 it also requires the value R-column (ie the actual number you are summing up) to be different from 0
You could also add the same criteria 'ESL Info'!$R:$R, "<>0" to your SUMIFS, but that isn't necessary, because a 0 doesn't provide anything to you sum, thus it doesn't matter if it's included in the sum or not ...
And depending on the Excel version you are using, you may even have the AVERAGEIFS function available, which does exactly what you want
=AVERAGEIFS('ESL Info'!$R:$R,'ESL Info'!$H:$H;$B$28,'ESL Info'!$R:$R,"<>0")
I am using a Tableau worksheet having 10 factories (entries) and 10 measure values for each factory/entry. There are a total of 100 columns in my Tableau worksheet.
I want to hide all columns whose value is zero and only show non zero values. But since each column is a different measure value, I can't filter or sort them. How do I go about this?
If you have tableau prep, then melt your data in pivoting. In prep you can easily remove nil or zero values easily.
Ideally you should have 11 columns, 1 for factory_id and other 10 for measures.
Alternatively, break all 10 factories in 10 groups of data and Union them after adding an id field for each group.
This link will help https://www.tableau.com/about/blog/2018/4/how-perform-coordinated-pivots-tableau-prep-86661
Suppose I have 121 elements and want to get all combinations of 4 elements taken at a time, i.e. 121c4.
Since combnk(1:121, 4) takes a lot of time, I want to go for 2% of that combination by providing:
z = 1:50:length(121c4(:, 1))
For example: 1st row, 5th row, 100th row and so on, up to 121c4, picking only those rows from a 121c4 matrix without generating the complete combination (it's consuming too much for large numbers like 625c4).
If you haven't defined an ordering on the combinations, why not just use
randi(121,p,4)
where p is the number of combinations you want in your set ? With this approach you may, or may not, want to replace duplicates.
If you have defined an ordering on the combinations, tell us what it is.
May be it is so simple but I'm new to Matlab and not good in Timestamps issues in general. Sorry!
I have two different cameras each contains timestamps of frames. I read them to two arrays TimestampsCam1 and TimestampsCam2:
TimestampsCam1 contains 1500 records and the timestamps are in Microseconds as follows:
1 20931160389
2 20931180407
3 20931200603
4 20931220273
5 20931240360 ...
and TimestampsCam2 contains 1000 records and the timestamps are in Milliseconds as follows:
1 28275280
2 28315443
3 28355607
4 28395771
5 28435935 ...
The first camera starts capturing first and ends a bit later than the second camera. So what I need to do is to know exactly where a frame from first camera is captured at the same time (or nearly the same time) by the other camera. In other words, I want to align the two arrays(cameras) in time according to the timestamps. I want to get at the end two arrays of same size where each record is tempo-aligned to the corresponding record in the other array.
Many thanks to all!
Sam
Make sure they are in the same unit of measurement, e.g. microseconds
Create an index which contains all values, except duplicates, suppose this one is 2400 records long
Create two NaN vectors of length 2400 by putting the value (for example the framenumber) at the place where the index matches the timestamp
Now you have two aligned vectors with NaNs to pad them where required.
The mode-function in Matlab returns the value that occurs most frequently in a dataset. But "when there are multiple values occurring equally frequently, mode returns the smallest of those values."
This is not very useful for what i am using it for, i would rather have it return a median, or arithmetic mean in the absence of a modal value (as they are at least somewhat in the middle of the distibution). Otherwise the results of using mode are far too much on the low side of the scale (i have a lot of unique values in my distribution).
Is there an elegant way to make mode favor more central values in a dataset (in the absence of a true modal value)?
btw.: i know i could use [M,F] = mode(X, ...), to manually check for the most frequent value (and calculate a median or mean when necessary). But that seems like a bit of an awkward solution, since i would be almost entirely rewriting everything that mode is supposed to be doing. I'm hoping that there's a more elegant solution.
Looks like you want the third output argument from mode. EG:
x = [1 1 1 2 2 2 3 3 3 4 4 4 5 6 7 8];
[m,f,c] = mode(x);
valueYouWant = median(c{1});
Or (since median takes the average of values when there are an even number of entries), in the cases where an even number of values may have the same max number of occurrences, maybe do something like this:
valueYouWant = c{1}(ceil(length(c{1})/2))