Creating Dynamic Columns in Power Query with Expression Lookups - etl

I have a Source file that has a set of columns, each of binary type (true, false). I then have a processing (transform) table which has one or more rows, each row specifying a new column to be added to the Source, along with the expression to use to populate that column based on existing columns. In Power Query, I want to be able to extend the Source table with these additional column definitions. There can be any number of transform rows, so I would need to do this dynamically based on row count. Click on link below for an illustration of what I'm shooting for.
I believe this can be achieved using List.Accumulate in Power Query, but I haven't figured out exactly how to do it. Any suggestions?

Here is a method using List.Generate:
let
Transform = Excel.CurrentWorkbook(){[Name="Transform"]}[Content],
#"Transform Table" = Table.TransformColumnTypes(Transform, {{"Col Name", type text},{"Col Formula", type text}}),
Source = Excel.CurrentWorkbook(){[Name="Source"]}[Content],
#"Source Table" = Table.TransformColumnTypes(Source,{{"A", type logical}, {"B", type logical}, {"C", type logical}}),
addCol = List.Last(
List.Generate(
()=>[c=Table.AddColumn(#"Source Table", #"Transform Table"[Col Name]{0},
Expression.Evaluate("each " & #"Transform Table"[Col Formula]{0}), type logical),
idx=0],
each [idx] < Table.RowCount(#"Transform Table"),
each [c=Table.AddColumn([c], #"Transform Table"[Col Name]{[idx]+1},
Expression.Evaluate("each " & #"Transform Table"[Col Formula]{[idx]+1}), type logical),
idx=[idx]+1],
each [c]))
in
addCol

Related

How to aggregate/group the data from one table and output the result as another table in PowerBI?

I have a Raw Data Table as shown in the screenshot below:
I want to group the data in the raw data table into the Output Table as shown in the screenshot below:
Basically the output table is counting the number of student for each understanding level in different intake. May I know how should I get the output table from the raw data table? I'm still new in Power Query, any help will be greatly appreciated!
This is what I have tried:
Code:
= Table.Group(Source, {"Intake"}, {
{"Count_Little_Understand", each Table.RowCount(Table.SelectRows(_, each ([Topic 1] = "Little Understanding"))), Int64.Type},
{"Count_General_Understanding", each Table.RowCount(Table.SelectRows(_, each ([Topic 1] = "General Understanding"))), Int64.Type},
{"Count_Good_Understand", each Table.RowCount(Table.SelectRows(_, each ([Topic 1] = "Good Understanding"))), Int64.Type},
{"Count_Fully_Understand", each Table.RowCount(Table.SelectRows(_, each ([Topic 1] = "Fully Understand"))), Int64.Type}
})
I only able to get the table by individual Topic, not sure how to include other Topic appended below and also add another extra column to label the Topic as shown in my second screenshot. Hope to get some advice/help on how should I modified the code. Thank you/1
I've rebuilt a similar but shorter table:
Now we first go into Transform (1), mark the Topic Cols (2) and Unpivot Columns (3).
Your table now looks like the following screenshot. Finally, we select the Value column (1), click on Pivot Column (2), select Employee Name (3).
Result:
You can Unpivot the Topic columns, then Pivot the Understanding column, using Count of Employee Name as the aggregate value.
Then simply reorder columns and sort rows, to suit the output you need:
#"Unpivoted Topic" = Table.UnpivotOtherColumns(#"Raw Data Table", {"Employee Name", "Intake"}, "Topic", "Understanding"),
#"Pivoted Understanding" = Table.Pivot(#"Unpivoted Topic", List.Distinct(#"Unpivoted Topic"[Understanding]), "Understanding", "Employee Name", List.NonNullCount),
#"Reordered Columns" = Table.ReorderColumns(#"Pivoted Understanding",{"Intake", "Topic", "Little Understanding", "General Understanding", "Good Understanding", "Fully Understand"}),
#"Sorted Rows" = Table.Sort(#"Reordered Columns",{{"Topic", Order.Ascending}, {"Intake", Order.Ascending}})
Output:

Is there any way how to refer actual column name as variable in Power Query

I am new to Power Query and I would like to ask more experienced people about it.
I am trying to solve problem with Text.Combine where I would like to combine together value in specific column and column name of actual cell.
Do you have any idea?
My idea is formula similar to this:
=Text.Combine({[kod], Column.Name},";")
Thank you very much for answer.
Tomas
Edit 8.12.2021:
#horseyride
I actually try fill columns automatically with data in following format where first part will be value from actual row and actual column name:
For e.g.:
8M0183:F01A0101.B in first row, second column,
8M0182:F01A0102.A in second row, first column
Table example mentioned bellow.
Thank you very much for all answers.
see if this works for you. It combines the KOD column with the column name into each null cell, for every column that is not named KOD
It finds all column not named KOD. It converts those to text. It replaces all nulls with a placeholder, here "xxx". We unpivot to get everything to just three columns. We then combine the column title and the cell contents if the cell contents is equal to the placeholder. Pivot to get back to original format
let Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
ColumnList=List.Difference(Table.ColumnNames(Source),{"KOD"}),
ConvertToText= Table.TransformColumnTypes (Source,List.Transform(ColumnList, each {_ , type text})),
ReplaceNullsWithPlaceholder = Table.ReplaceValue(ConvertToText,null,"xxx",Replacer.ReplaceValue,ColumnList),
#"Unpivoted Other Columns" = Table.UnpivotOtherColumns(ReplaceNullsWithPlaceholder, {"KOD"}, "Attribute", "Value"),
CombineColumnAndRow = Table.AddColumn(#"Unpivoted Other Columns", "Value2", each if [Value]="xxx" then [Attribute]&":"&[KOD] else [Value]),
#"Removed Columns" = Table.RemoveColumns(CombineColumnAndRow,{"Value"}),
#"Pivoted Column1" = Table.Pivot(#"Removed Columns", List.Distinct(#"Removed Columns"[Attribute]), "Attribute", "Value2")
in #"Pivoted Column1"

Bring Value with Sumifs in Pow.Query language to specified row, and column(location)

Next step? I have brought with sumifs and a lot sumif from other workbook, information to the exact row, column in excel workbook. Now I want to do the same with query language. I can bring two values if condition is met, but then it is unclear how I will bring the total sum to the one row in excel workbook. Can anyone show me the path? I guess I will need Data Model...
= Table.AddColumn(#"Changed Type", "Sumif", each if [Column2] =2 or [Column2]=1 then [Column3]+[Column4] else 0)
let
Source = Folder.Files...
#"C:\Users...
#"Imported Excel" = Excel.Workbook(#"C:\...
SegPL_Chart = #"Imported Excel"{[Name="SegPL_Chart"]}[Data],
#"Removed Top Rows" = Table.Skip(SegPL_Chart,12),
#"Removed Alternate Rows" = Table.AlternateRows(#"Removed Top Rows",1,1,90),
#"Promoted Headers" = Table.PromoteHeaders(#"Removed Alternate Rows"),
#"Filtered Rows" = Table.SelectRows(#"Promoted Headers", each ([Col1]="1" or [Col1]="2")),
#"Table Group = Table.Group(#"Filtered Rows", {}, List.TransformMany(Table.ColumnNames(#"Filtered Rows",(x)=>{each if x = "Names" then "Totals" else List.Sum(Table.Column(_,x))},(x,y)=>{x,y})),
#"append" = Table.Combine({#"Filtered Rows",#"Table Group"})
in
#"append"
It gives an error "in" Token comma needed..? What else I need to do bring total rows?
You can use several steps to create several helper columns with intermediate results of conditional sums. Then you can create a new column, sum up all the intermediate results and the delete the helper columns with the intermediate results.
Keep in mind that unlike Excel, the calculations in Power Query always return constants and you can then delete calculated columns you no longer need. So,
Create helper column 1 with complicated IF and Sum scenario
Create helper column 2 with complicated IF and Sum scenario
Create total column to add column 1 + column 2
Delete helper columns and keep only the total column
That gives me exact result what I was looking for, but it is with DAX formula in PowerPivot:
=SUMX(FILTER('TableName',[ColName] = 1),'TableName'[ColName2])
So would be glad to convert it to Power-Query formula

Power Query: Selecting multiple elements in 'value field settings' to measure a specifc field

I'm trying to create a measure that averages the 29 elements' value [Overtime/Hours_worked] into one cell, visualised by the attached image.
Cell F32 currently shows [AverageA Total Overtime/Total Hours_worked] but I want it to be an average of the 29 rows' values as displayed in cell H32, =AVERAGEA(F3:F31).
The elements' figures are based upon underlying data from Data$, currently amounting to ~150k rows. When creating a measure that's averaging the elements' values from Column E [AvereageA Overtime/Hours_worked] and showing as a % of the 29 elements' aggregate %, I'm running into the problem of averaging the separate elements' underlying data taken from Data$. Worth noting is that F3:F31 is redundant in this instance, I'm looking for the average of the 29 elements' values in column E and not their respective averages shown in column F.
Am I right to use measure here or is there a better way to approach it? If measures can be used, is there a way to design the measure so that it refers to the Pivot Table's shown data instead of the underlying data taken from Data$? For instance by designing the measure to refer to column E in the pivot table?
Side note
The table needs to remain dynamic since Data$ is being updated regularly. I'm relatively new to Power Query so I'm not sure if there are other ways to solve this, i.e. through MDX, but I doubt I'll be able to sort that out myself.
Any and all help is appreciated, thanks.
I'm not sure how you are computing the individual entries in the AverageA Total Overtime/Total Hours_worked (so I left it blank), but to compute the totals and averages for the other columns, you can use the Table.Group command in a special way with an empty list for the key (so as to return the entire table for the Aggregation operations).
Given:
M Code
read the comments in the code to understand the algorithm
If your overtime% column is in your original data, you can just delete those code lines that add that column
let
//be sure to change table name in next line to your actual table name
Source = Excel.CurrentWorkbook(){[Name="wrkTbl"]}[Content],
//set data types
#"Changed Type" = Table.TransformColumnTypes(Source,{
{"Area", type text}, {"Hours_worked", Int64.Type}, {"Overtime", Int64.Type}}),
//Add the percent overtime column
#"Added Custom" = Table.AddColumn(#"Changed Type", "Overtime/Hours_worked",
each [Overtime]/[Hours_worked], Percentage.Type),
//Use Table.Group to compute total/averages for the last row
//Be sure to use the exact same names as used in the original table
#"Grouped Rows" = Table.Group(#"Added Custom", {}, {
{"Area", each "Totals",type text},
{"Hours_worked", each List.Sum([Hours_worked]), Int64.Type},
{"Overtime", each List.Sum([Overtime]), Int64.Type},
{"Overtime/Hours_worked", each List.Sum([Overtime])/List.Sum([Hours_worked]), Percentage.Type},
{"AverageA Overtime/Hours_worked", each List.Average([#"Overtime/Hours_worked"]), Percentage.Type}
}),
//Append the two tables to add the Totals row
append= Table.Combine({ #"Added Custom", #"Grouped Rows"})
in
append
results in =>

Is there an ISNUMBER() or ISTEXT() equivalent for Power Query?

I have a column with mixed types of Number and Text and am trying to separate them into different columns using an if ... then ... else conditional. Is there an ISNUMBER() or ISTEXT equivalent for power query?
Here is how to check type in Excel Powerquery
IsNumber
=Value.Is(Value.FromText([ColumnOfMixedValues]), type number)
IsText
=Value.Is(Value.FromText([ColumnOfMixedValues]), type text)
hope it helps!
That depends a bit on the nature of the data and how it is originally encoded. Power Query is more strongly typed than Excel.
For example:
Source = Table.FromRecords({[A=1],[A="1"],[A="a"]})
Creates a table with three rows. The first row's data type is number. The second and third rows are both text. But the second row's text could be interpreted as a number.
The following is a query that creates two new columns showing if each row is a text or number type. The first column checks the data type. The second column attempts to guess the data type based on the value. The guessing code assumes everything that isn't a number is text.
Example Code
Edit: Borrowing from #AlejandroLopez-Lago-MSFT's comment for the interpreted type.
let
Source = Table.FromRecords({[A=1],[A="1"],[A="a"]}),
#"Added Custom" = Table.AddColumn(Source, "Type", each
let
TypeLookup = (inputType as type) as text =>
Table.FromRecords(
{
[Type=type text, Value="Text"],
[Type=type number, Value="Number"]
}
){[Type=inputType]}[Value]
in
TypeLookup(Value.Type([A]))
),
#"Added Custom 2" = Table.AddColumn(#"Added Custom", "Interpreted Type", each
let
result = try Number.From([A]) otherwise "Text",
resultType = if result = "Text" then "Text" else "Number"
in
resultType
)
in
#"Added Custom 2"
Sample output
Put it in logical test format
Value.Type([Column1]) = type number
Value.Type([Column1]) = type text
The function Value.Type returns a type, so by putting it in equation thus return a true / false.
Also, equivalently,
Value.Type([Column1]) = Date.Type
Value.Type([Column1]) = Text.Type
HTH
ISTEXT() doesn't exist in any language I've worked with - typically any numeric or date value can be converted to text so what would be a false result?
For ISNUMBER, I would solve this without any code by changing the Data Type to a number type e.g. Whole Number. Any rows that don't convert will show Error - you can then apply Replace Errors or Remove Errors to handle them.
Use Duplicate Column first if you don't want to disturb the original column.
I agree with Mike Honey.
I have a SKU code that is a mix of Char and Num.
Normally the last 8 Char are Numbers but in some weird circumstances the SKU is repeated with an additional letter but given the same EAN which causes chaos.
by creating a new temp column using Text.End(SKU, 1) I get only the last character. I then convert that column to Whole Number. Any Error rows are then removed to leave only the rows I need. I then delete the temp Column and am left with the Rows I need in the format I started with.

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