I am trying to compute a percentage difference between two values - market index levels separated by a period of time (the period will be determined by user input in a Power BI Slicer tool). I don't understand how I can cross reference values DAX uses by the associated date.
Value % difference from Value =
VAR __BASELINE_VALUE = SUM('Equity Markets (2)'[Value])
VAR __VALUE_TO_COMPARE = SUM('Equity Markets (2)'[Value])
RETURN
IF(
NOT ISBLANK(__VALUE_TO_COMPARE),
DIVIDE(__VALUE_TO_COMPARE - __BASELINE_VALUE, __BASELINE_VALUE)
)
"Value" is a column in a table "Equity Markets (2)" the table also includes a "Date" column.
What is the syntax for selecting a value from Value based on an associated date?
Apologies for asking such a basic question - feels like 30 sec of googling should have done it for me.
The slicer is engaging with the bar graph correctly - I know becouse I'm measuring the levels. I think all the % changes are zero because I'm evaluating x/x -1
percentage change =
VAR
__EarliestValue = CALCULATE(SUM('Equity Markets (2)'[Value]),
FIRSTDATE('Equity Markets (2)'[Date]))
VAR __LastDateValue = CALCULATE(SUM('Equity Markets (2)'[Value]),
LASTDATE('Equity Markets (2)'[Date]))
RETURN
CALCULATE(
DIVIDE(__LastDateValue,__EarliestValue)-1)
Related
I am quite new to working with DAX and Power BI so please don't judge. My problem seems (and might be) simple. Anyways, here we go:
I have a dataset that contains 3 colulmns: Date (date), Price (float), Performance (%)
Attribute descriptions:
Date and Price are constants that are pulled from an external data source. Performance is a variable of the price change over time in percent. It is the percentage change of the price of the current date to the first date in the time-series selection (Selected "from date" of date slicer visual).
I want to create a dynamic line chart that shows performance over time. Difficulty here is when I change the "from date" I want the performance to be variable. Meaning, the price of the chosen "from date" is the new base price and should be calculated accordingly.
Formula:
Date = t, price at date t = pt, performance at date t = pert
Date range:
1.1.2000 to 31.12.2010
Initial situation when "date from" in the date slicer visual = 1.1.2000:
t0 = 1.1.2000
pt0 = 5,00
pert0 = 0%
t5 = 6.1.2000
pt5 = 5,054
pert5 = (pt5-pt0)/pt0 = 1.08%
After changing date slicer so that "from date" is now 10.10.2009:
t0new = 10.10.2009
pt0new = 9,938
pert0new = 0%
t5new = 15.10.2009
pt5new = 9,832
pert5new = (pt5-pt0)/pt0 = -1,05%
As described, I want whatever is selected as starting point from the date slicer as the new base value for the performance calculation and the line chart should adjust accordingly.
I know how to do the dynamic line chart but I cannot figure out the measures and calculated columns I need to do so.
Any help is very much appreciated!
Cheers,
MLU
Calculate the benchmark as the price associated to the first date in
the period. SELECTEDVALUE assumes you have one price per Date,
otherwise use an aggregator (e.g. MIN, MAX, AVERAGE). I use ALLSELECTED so the Benchmark is affected only by Filter Context (slicers) and you can easily use it in visualizations that change the context.
Save our benchmark in a variable for later use
Divide each price by the benchmark. Here we need to apply an aggregator to the Price,
I used AVERAGE assuming you have only one Price per day, therefore, the result is the
price itself.
Here is the measure:
Price vs Dynamic Benchmark :=
VAR vbenchmark = CALCULATE(SELECTEDVALUE(Dataset[Price]),FILTER(ALL( Dataset[Date]), Dataset[Date] = CALCULATE(min(Dataset[Date])), ALLSELECTED(Dataset))
return
AVERAGE(Price) / vbenchmark
I am currently building an app to teach myself Swift so am still very new. I’ve encountered a problem. The app is a timetable creator. I have up to twelve subjects that all have points. These points are then spread across days. I have a concept for code that will allocate the points fine using loops but wondered whether there was something to reduce the amount of code rather than, what I currently have, something like this for each subject:
subject1.monpts = 20
subject1.tuepts = 20
subject1.wedpts = 20
subject1.thurpts = 20
subject1.fripts = 20
subject1.satpts = 20
subject1.sunpts = 20
This, x12, is a lot of code. But I need it so that each subject has an option for points for each day of the week (which the app will then allocate time based on these points). To print the timetable, I am putting each subjectX.daypts together but this means I’m writing out 12 subjects for each day.
I also need to only display something if the variable actually has a value. I plan to do this using if statements but that means writing a statement for every single variable which at the moment is 12 x 7 = 48! E.g. (ignore the formating - just for concept)
if subjects1.monpts = 0 {
subjects1monLabel = isHidden.false
// or just a print / don't print statement
}
I feel as if I'm missing an easier way to do this!
Here is a picture that explains the concept a bit better:
If you want to save information about those fields you can have a dictionary with keys of a enum and values of ints like so:
enum WeekDay: CaseIterable {
case monday, tuesday, wednesday, thursday, friday, saturday, sunday
}
struct Subject {
var pointsForWeekDay: [WeekDay: Int]
}
Now you could do:
var pointsForWeekDay = Dictionary(uniqueKeysWithValues:
WeekDay.allCases.map { weekDay in
return (weekDay, 20)
}
)
var subject = Subject(pointsForWeekDay: pointsForWeekDay)
CaseIterable allows you to access all values of your enum.
Map takes every weekDay and creates an array of tuples with your Int values.
And finally you can combine that to have a complete Dictionary with uniqueKeysWithValues initializer, which takes an array of the produced tuples.
Your whole vision of how to organize this material is upside down. Start by thinking about what all your subjects have in common: points for each of the seven days, label hidden for each of the seven days, and so forth. Now incorporate that into a type (a struct): Subject. Now instead of subjects1..., subjects2... and so forth, you have an Array of Subject.
So: any time you have variables named with a number, that should be an array instead. Any time you have clumps of repeated concepts, that should be a type instead.
Even the notion of the seven days of the week could itself be condensed in the same way. If all we're talking about is points per day, an array of seven numbers would do.
So we'd end up with a skeleton like this:
struct Subject {
var dayPoints : [Int]
}
var myTwelveSubjects : [Subject]
...and you can build that out as more requirements come online, such as whether a day is hidden.
This question is a slightly varied version of this one...
Now I'm using Measures instead of Calculated columns and the date is static instead of having it based on a dropdown list.
Here's the Power BI test .pbix file:
https://drive.google.com/open?id=1OG7keqhdvDUDYkFQFMHyxcpi9Zi6Pn3d
This printscreen describes what I'm trying to accomplish:
Basically the date in P6 Update table is used as a cut date and will be fixed\static. It's imported from an Excel sheet where the user can customize it however they want.
Here's what should happen when a matching row in Test data table is found for P6 Update date:
column Earned Daily - must have its value summed with the next row if there's one;
column Earned Cum - must grab the next row's value;
all the previous rows should remain intact, that is, their values won't change;
all subsequent rows must have their values assigned 0.
So for example:
If P6 Update is 1-May-2018, this is the expected result:
1-May 7,498 52,106
2-May 0 0
If P6 Update is 30-Apr-2018, this is the expected result:
30-Apr 13,173 50,699
1-May 0 0
2-May 0 0
If P6 Update is 29-Apr-2018, this is the expected result:
29-Apr 11,906 44,608
30-Apr 0 0
1-May 0 0
2-May 0 0
and so on...
Hope this makes sense.
This is easier in Excel, but trying to do this in Power BI is making me go nuts.
I will ignore previously asked related questions and start from scratch.
First, create a measure:
Current Earn =
CALCULATE (
SUM( 'Test data'[Value]),
'Test data'[Act Rem] = "Actual Units",
'Test data'[Type] = "Current"
)
This measure will be used in other measures, to save you from typing all these conditions ("Actual Units" and "Current") again and again. It's a great practice to re-use measures in other measures - saves work, makes code cleaner and easier to refactor.
Create another measure:
Cut Date = SELECTEDVALUE('P6 Update'[Date])
We will use this measure whenever we need a cut off date. Please note that it does not have to be hard-coded - if P6 table contains a list of dates, you can create a pull-down slicer from the dates, and can choose the cut-off date dynamically. The formula will work properly.
Create third measure:
Next Earn =
VAR Cut_Date = [Cut Date]
VAR Current_Date = MAX ( 'Test data'[Date] )
VAR Next_Date = Current_Date + 1
VAR Current_Earn = [Current Earn]
VAR Next_Earn = CALCULATE ( [Current Earn], 'Test data'[Date] = Next_Date )
RETURN
SWITCH (
TRUE,
Current_Date < Cut_Date, Current_Earn,
Current_Date = Cut_Date, Current_Earn + Next_Earn,
BLANK ()
)
I am not sure if "Next Earn" is a good name for it, hopefully you will find a more intuitive name. The way it works: we save all necessary inputs into variables, and then use SWITCH function to define the results. Hopefully it's self-explanatory. (Note: if you need 0 above Cut Date, replace BLANK() with 0).
Finally, we define a measure for cumulative earn. It does not require any special logic, because previous measure takes care of it properly:
Cum Earn =
VAR Current_Date = MAX('Test data'[Date])
RETURN
CALCULATE(
[Next Earn],
FILTER(ALL('Test data'[Date]), 'Test data'[Date] <= Current_Date))
Result:
I attempt to show a tersely formatted date/time on the x-axis in a graphview chart. As per the API Code examples, I set HumanRounding to false when using using a date formatter on that axis. I'm also setting the NumHorizontalLabels to 3 in order to display reasonably OK in both orientations.
This results in e.g. the following, where the date labels show as a black shape, and the LineChart background is different. I'm speculating that the black shape is the result of all my date data points overwriting each other:
With HumanRounding set to true (commented out), I get labels showing, but instead of the expected 3 evenly distributed labels, they are unpredictably spread out and/or not equal to 3, sometimes the labels over-write each other, sometimes they are bunched on the left...
The number of date data-points on the x-axis can vary depending on how much history the user has selected. Note that this can vary from 60 to thousands of minutes.
Here's the code that receives data and charts it. Note that the unixdate retrieved from wxList elements has already been converted to a Java date (by multiplying by 1000) by the time they get used here (the time portion of the x-axis are in fact correct when they do show up in a reasonably distributed manner):
protected void onPostExecute(List<WxData> wxList) {
// We will display MM/dd HH:mm on the x-axes on all graphs...
SimpleDateFormat shortDateTime = new SimpleDateFormat("MM/dd HH:mm");
shortDateTime.setTimeZone(TimeZone.getTimeZone("America/Toronto"));
DateAsXAxisLabelFormatter xAxisFormat = new DateAsXAxisLabelFormatter(parentContext, shortDateTime);
if (wxList == null || wxList.isEmpty()) {
makeText(parentContext,
"Could not retrieve data from server",
Toast.LENGTH_LONG).show();
} else {
// Temperature Celcius
GraphView tempGraph = findViewById(R.id.temp_graph);
tempGraph.removeAllSeries();
tempGraph.setTitle(parentContext.getString(R.string.temp_graph_label));
DataPoint[] tempCArray = new DataPoint[wxList.size()];
for (int i = 0; i < wxList.size(); i++) {
tempCArray[i] = new DataPoint(wxList.get(i).getUnixtime(), wxList.get(i).getTempC().doubleValue());
}
LineGraphSeries<DataPoint> tempCSeries = new LineGraphSeries<>(tempCArray);
tempGraph.addSeries(tempCSeries);
tempGraph.getGridLabelRenderer().invalidate(false, false);
tempGraph.getGridLabelRenderer().setLabelFormatter(xAxisFormat);
tempGraph.getGridLabelRenderer().setNumHorizontalLabels(3);
tempGraph.getViewport().setMinX(wxList.get(0).getUnixtime());
tempGraph.getViewport().setMaxX(wxList.get(wxList.size() - 1).getUnixtime());
tempGraph.getViewport().setXAxisBoundsManual(true);
// Code below seems buggy - with humanRounding, X-axis turns black
// tempGraph.getGridLabelRenderer().setHumanRounding(false);
...
I have tried many variations,but I cannot get the graph to consistently display 3 datetimes evenly spread out, for both orientations, for varyings sample sizes. Any help is appreciated.
I have a bunch of daily change % data. I would like to calculate cumulative change, which should just be (1+change)*previous day in a chart in Tableau.
Seems simple enough right? I can do it in a few seconds in Excel, but I've tried for hours to get it to work in Tableau and cannot do it.
My thought was that I can create a column that is (1+daily change%), then try to do a compound product. However, I can't seem to get it to work.
I can't attach any files here so I pasted the data, along with a column that is "cum change", which is what I would like the calculation to be.
Thank you much in advance!
Date Daily Change Cum Change
4/1/2015 0.47% 1
4/2/2015 0.56% 1.0056
4/3/2015 -0.72% 0.99835968
4/6/2015 -0.56% 0.992768866
4/7/2015 -0.80% 0.984826715
4/8/2015 0.44% 0.989159952
4/9/2015 -0.66% 0.982631497
4/10/2015 0.99% 0.992359549
4/13/2015 0.92% 1.001489256
4/14/2015 0.73% 1.008800128
4/15/2015 0.95% 1.018383729
4/16/2015 0.42% 1.022660941
4/17/2015 0.52% 1.027978778
4/20/2015 0.02% 1.028184373
4/21/2015 0.56% 1.033942206
4/22/2015 0.35% 1.037561004
4/23/2015 -0.34% 1.034033296
4/24/2015 0.18% 1.035894556
4/27/2015 0.61% 1.042213513
4/28/2015 0.46% 1.047007695
4/29/2015 0.94% 1.056849568
Create a calculated field:
IF INDEX() = 1
THEN 1
ELSE
(1 + AVG([Daily Change])) * PREVIOUS_VALUE(1)
END
The condition checking to see if it's the first row of the partition (INDEX() = 1) is necessary to ensure that the first value of the field is a 1. After that, you can just use the self-referential PREVIOUS_VALUE() to get the previous value of this same calculation.