Plotting an upper envelope function in Excel - excel

I have got data points of a sound sample from Audacity which I exported to a .txt file and imported in Excel. Is it possible to plot an upper envelope function in Excel?
(In the end I have to determine the reverberation time, so the time in which the loudness decreases with 60dB.)

For a decaying oscillation such as this or a damped pendulum, the decay envelope can be found by looking at the difference between each sampled reading. You then need to see where the is a change in gradient from +ve to -ve. (or zero on one side). To do this some logical operators are used.
Method:
Consider data starting at column A row 5 for time and Column B row 5 for first data value.
Create a column which has the value minus the previous value. [ C6=B6-B5 etc.]
Next do a column for the gradient change giving a "flag" of 1 for a positive to negative or zero inflection [D7= IF (AND(C7>0,C6<=0],1,0)
This should produce a column of data that corresponds to the peaks.
In the next columns use the flag to get the original co-ordinates to display
[E7 =IF (D7=1,A7,"")] For time and [F7 IF(D7=1,B7,"")]
Copy this data using "Value" only in the paste option to yet another column.
Filter this to exclude the null data.
Beware of aliasing in data set.
Not the most elegant of solutions (and some steps can be linked -for clarity shown separately) but it works.
Tech99m

Related

In Excel: How to built a graph with time as X, names as Y with multiples series?

I am looking for a way to make a specific graph in Excel and I can't find a solution in Excel or on the web.
I have data about an online training with people completing parts of a course at a certain time:
FullName
Course
TIME
Name-A
Part 1
23/03/2022 10:38
Name-A
Part 2
23/03/2022 12:07
Name-A
Part 3
23/03/2022 16:55
Name-B
Part 1
11/03/2022 15:14
Name-B
Part 2
22/03/2022 12:08
Name-B
Part 3
28/03/2022 16:06
Name-B
Part 4
30/03/2022 14:55
Name-B
Part 5
18/04/2022 08:13
Name-C
Part 1
11/04/2022 15:25
Name-C
Part 2
20/04/2022 13:50
I would like to have a specific graph of this data:
On the vertical axis: one row for each user' name: Name-A, Name-B and Name-C.
On the horizontal axis: continuous time (say, in days) From the minimum time in the table (or less) to the maximum (or more)
Series of plots for the data: Each part of the course (from Part 1 to Part 5 here) would be a series of dots of a specific color, placed on the right row (for a learner's name) above the corresponding time on the horizontal axis.
Do you have any idea on how it could be achieved?
All the best, R.S.
Edit: The table does not appear as in the preview so i try to add a screenshot:
Screenshot of the table
So one way to visualise this as mentioned in the comments is to create a separate series for each person and show passing each part of the course as a vertical step:
It's based very loosely on this but I've set each day in the date range as the x-coordinates and used a lookup to transform the data in H2
=RIGHT(XLOOKUP($G2+TIME(23,59,59),FILTER($C$2:$C$11,$A$2:$A$11=H$1),FILTER($B$2:$B$11,$A$2:$A$11=H$1),0,-1))+(COLUMN()-COLUMN($G$1))*10
pulled down and across to give
Explanation
The data for the graph has dates spanning the times in the raw data for its x-coordinates (column G). I generated it manually but could have used Sequence in Excel 365.
There are three columns of y-values, H to J, generating a separate series for each person. The three lines are initially spaced out by 10 units based on the column number. In the formula above, the raw data is filtered by the person's name so the headers in columns H, I or J match the names in column A in the raw data. Xlookup is used with 'next smallest' match so where the date in column G is greater or equal to the date/time in column C it will return the corresponding course from column B. Because column C actually contains date/times, I have added almost 24 hours when matching the date in column G to make sure that a match is found if the day is the same, regardless of time. In a case like Name-A, where three courses are completed in the same day, this will automatically select the last one (Part 3). Then I take the right-hand character of the course name (which is a digit in the sample data) and add it to the relative column number multiplied by 10. If there is no match, Xlookup returns zero so you just get the initial value for each series (10, 20 or 30), otherwise the result will be an increase by one unit each time a course is passed. If you couldn't assume the last character of the course name was a digit, you would need a lookup to assign a number to each course name.
The data is then plotted on a scatter graph with points joined by straight lines. I had to adjust the x-axis manually to make the range correct and the labelling clearer.
This could be done without Excel 365, probably using Aggregate to get the highest row number with a condition on the name and date.
EDIT
I could have achieved the same result much more easily using Countifs to find how many courses had been passed by a certain person by a certain date:
=COUNTIFS($A$2:$A$11,H$1,$C$2:$C$11,"<="&$G2+TIME(23,59,59))+(COLUMN()-COLUMN($G$1))*10
This wouldn't have needed Excel 365. If you needed to give different courses different weightings, you could do this with a sumproduct and a lookup, also fairly straightforward.

Get result of difference of two columns in a matrix in third column

Above is a matrix in PowerBI that displays the amount and target amount for various divisions. I want to calculate the different between actual amount and target amount and display it in a third column in the matrix. I tried creating a column that calculates the difference between these two columns in the data table. But the data displayed in the matrix is not what I wish for it to be. I want the matrix to display the difference between the target and actual amount based on the values in the matrix only (which are derived based on certain filters applied). I do not want to get the difference of all the values in the dataset.
I am completely new to PowerBI and any help for the same would be highly appreciated.
Simply, use calculate. The value is the result of the expression evaluated in a modified filter context. That means in your current filter/row context.
diff = calculate([Target] - [Amount])

Spotfire: calculating difference between two rows in same column based on attributes in different columns

I am new to Spotfire and need help in getting the right expression for a calculated column.
My Data contains different subjects grouped in column ID. For every ID, Bodyweight was measured on different days. Days are given in column Day and stated as 1,2,3...
The last day is denoted by Last and Bodyweight measurements given in another column. Another column is present which is called Baseline. The Body weight measured is considered as baseline if the column contains a Y for that row.
I need to insert a calculated column, which will contain the difference between Body measurement measured on Day denoted Last and Body measurement marked by Y in column Baseline.
This should be done for every new ID. I am not able to figure this out. Could someone advise me on how to go about it?
Here is an example attached
So, the calculated column for Rita will give -4 (body weight at Last=56 and BodyWeight at baseline=56, so 52-56 =-4)
the sample data you provided is a little weird, particularly the [Day] column. if it's within your control, I suggest to use actual dates rather than a number/string here.
barring that, I was able to get your desired results, but it required two calculated columns: the first one will consolidate the [Day] and [Baseline] columns into a single column, and the second one contains your desired info.
column 1, which I called Day (int):
CASE
WHEN [Day]="Last" THEN 1000000
WHEN [Baseline]="Y" THEN -1000000
WHEN [Day]!="Last" THEN Integer([Day])
END
I picked a random high and low max to establish a chronological order. this will put 1000000 in place of "Last" (if you have any programs that are longer than one million days, you'll need to increase this number). the same for the [Baseline] column, but that value will be -1000000, which is presumably the lowest value you will ever see in this column. both of these are assumptions and may not work for your implementation. finally, in all other cases, the day number will be used.
column 2, which I called Diff:
Last([Weight]) OVER (Intersect([Name],LastNode([Day (int)]))) -
First([Weight]) OVER (Intersect([Name],FirstNode([Day (int)])))
the first line uses what's called an OVER expression to retrieve the first value for [Weight], ordered by [Day (int)], per [Name]. the second line gives the reverse of that, and so the difference is calculated as -4 (or whatever is appropriate).

Combination of several INDEX and MATCH functions

I'm currently working on an evaluation excel sheet for forceplate data (showing vertical force development in jumps over time) and stumbled upon a problem that I couldn't manage to fix for the past days. Basically there are two main columns over ~ 4000 rows and 1 extra cell:
Column A shows time [in ms]
Column B shows vertical force measured at the time point in Column A
C1 is the already calculated peak force value before takeoff
I am now trying to define the timepoint of takeoff in an extra cell using INDEX and MATCH functions (FYI: the time of takeoff is when the vertical force value is close to 0 for the first time [range of lookup must be starting from the peak force value though!!], but never exactly 0 due to force plate drift in measurement)
My idea was this:
=INDEX(A2:A4000;MATCH(0;INDEX(B2:B4000;MATCH(C1;B2:B4000;0)):B4000;-1))
so the range
INDEX(B2:B4000;MATCH(C1;B2:B4000;0)):B4000
should define a range of force values starting at the peak force value (C1).
Unfortunately Excel will show me a timepoint where the force value is far away from 0. I've tried the same formula within an easier (but for my purpose faulty) range (B2:B4000) and it worked perfectly, so I guess the problem I'm dealing with lies somewhere within the range defined with the INDEX function.
I'd be glad if someone could help me out with this!
You are certainly on the right track. It seems you've correctly adjusted the range in the nested INDEX function but that MATCH function will retunr the position within the adjusted B2:B4000. You need to adjust A2:A4000 in the same way so that the position returned by MATCH will be correct.
=INDEX(INDEX(A2:A4000; MATCH(C1; B2:B4000; 0)):A4000; MATCH(0; INDEX(B2:B4000; MATCH(C1; B2:B4000; 0)):B4000; -1))
I don't have sample data to test that on but I believe it is correct.

Interpolating data points in Excel

I'm sure this is the kind of problem other have solved many times before.
A group of people are going to do measurements (Home energy usage to be exact).
All of them will do that at different times and in different intervals.
So what I'll get from each person is a set of {date, value} pairs where there are dates missing in the set.
What I need is a complete set of {date, value} pairs where for each date withing the range a value is known (either measured or calculated).
I expect that a simple linear interpolation would suffice for this project.
If I assume that it must be done in Excel.
What is the best way to interpolate in such a dataset (so I have a value for every day) ?
Thanks.
NOTE: When these datasets are complete I'll determine the slope (i.e. usage per day) and from that we can start doing home-to-home comparisons.
ADDITIONAL INFO After first few suggestions:
I do not want to manually figure out where the holes are in my measurement set (too many incomplete measurement sets!!).
I'm looking for something (existing) automatic to do that for me.
So if my input is
{2009-06-01, 10}
{2009-06-03, 20}
{2009-06-06, 110}
Then I expect to automatically get
{2009-06-01, 10}
{2009-06-02, 15}
{2009-06-03, 20}
{2009-06-04, 50}
{2009-06-05, 80}
{2009-06-06, 110}
Yes, I can write software that does this. I am just hoping that someone already has a "ready to run" software (Excel) feature for this (rather generic) problem.
I came across this and was reluctant to use an add-in because it makes it tough to share the sheet with people who don't have the add-in installed.
My officemate designed a clean formula that is relatively compact (at the expensive of using a bit of magic).
Things to note:
The formula works by:
using the MATCH function to find the row in the inputs range just before the value being searched for (e.g. 3 is the value just before 3.5)
using OFFSETs to select the square of that line and the next (in light purple)
using FORECAST to build a linear interpolation using just those two points, and getting the result
This formula cannot do extrapolations; make sure that your search value is between the endpoints (I do this in the example below by having extreme values).
Not sure if this is too complicated for folks; but it had the benefit of being very portable (and simpler than many alternate solutions).
If you want to copy-paste the formula, it is:
=FORECAST(F3,OFFSET(inputs,MATCH(F3,inputs)-1,1,2,1),OFFSET(inputs,MATCH(F3,inputs)-1,0,2,1
(inputs being a named range)
There are two functions, LINEST and TREND, that you can try to see which gives you the better results. They both take sets of known Xs and Ys along with a new X value, and calculate a new Y value. The difference is that LINEST does a simple linear regression, while TREND will first try to find a curve that fits your data before doing the regression.
The easiest way to do it probably is as follows:
Download Excel add-on here: XlXtrFunâ„¢ Extra Functions for Microsoft Excel
Use function intepolate().
=Interpolate($A$1:$A$3,$B$1:$B$3,D1,FALSE,FALSE)
Columns A and B should contain your input, and column G should contain all your date values. Formula goes into the column E.
A nice graphical way to see how well your interpolated results fit:
Take your date,value pairs and graph them using the XY chart in Excel (not the Line chart). Right-click on the resulting line on the graph and click 'Add trendline'. There are lots of different options to choose which type of curve fitting is used. Then you can go to the properties of the newly created trendline and display the equation and the R-squared value.
Make sure that when you format the trendline Equation label, you set the numerical format to have a high degree of precision, so that all of the significant digits of the equation constants are displayed.
The answer above by YGA doesn't handle end of range cases where the desired X value is the same as the reference range's X value. Using the example given by YGA, the excel formula would return #DIV/0! error if an interpolated value at 9999 was asked for. This is obviously part of the reason why YGA added the extreme endpoints of 9999 and -9999 to the input data range, and then assumes that all forecasted values are between these two numbers. If such padding is undesired or not possible, another way to avoid a #DIV/0! error is to check for an exact input value match using the following formula:
=IF(ISNA(MATCH(F3,inputs,0)),FORECAST(F3,OFFSET(inputs,MATCH(F3,inputs)-1,1,2,1),OFFSET(inputs,MATCH(F3,inputs)-1,0,2,1)),OFFSET(inputs,MATCH(F3,inputs)-1,1,1,1))
where F3 is the value where interpolated results are wanted.
Note: I would have just added this as a comment to the original YGA post, but I don't have enough reputation points yet.
alternatively.
=INDEX(yVals,MATCH(J7,xVals,1))+(J7-MATCH(J7,xVals,1))*(INDEX(yVals,MATCH(J7,xVals,1)+1)-INDEX(yVals,MATCH(J7,xVals,1)))/(INDEX(xVals,MATCH(J7,xVals,1)+1)-MATCH(J7,xVals,1))
where j7 is the x value.
xvals is range of x values
yvals is range of y values
easier to put this into code.
You can find out which formula fits best your data, using Excel's "trend line" feature. Using that formula, you can calculate y for any x
Create linear scatter (XY) for it (Insert => Scatter);
Create Polynominal or Moving Average trend line, check "Display Equation on
chart" (right-click on series => Add Trend Line);
Copy the equation into cell and replace x's with your desired x value
On screenshot below A12:A16 holds x's, B12:B16 holds y's, and C12 contains formula that calculates y for any x.
I first posted an answer here, but later found this question

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