Powershell - Import-CSV Group-Object SUM a number from grouped objects and then combine all grouped objects to single rows - powershell

Question

I have a question similar to this one but with a twist:
Powershell Group Object in CSV and exporting it
My file has 42 existing headers. The delimiter is a standard comma, and there are no quotation marks in this file.
master_account_number,sub,txn,cur,last,first,address,address2,city,state,zip,ssn,credit,email,phone,cell,workphn,dob,chrgnum,cred,max,allow,neg,plan,downpayment,pmt2,min,clid,cliname,owner,merch,legal,is_active,apply,ag,offer,settle_perc,min_pay,plan2,lstpmt,orig,placedate
The file's data (the first 6 columns) looks like this:
master_account_number,sub,txn,cur,last,first
001,12,35,50.25,BIRD, BIG
001,34,47,100.10,BIRD, BIG
002,56,9,10.50,BUNNY, BUGS
002,78,3,20,BUNNY, BUGS
003,54,7,250,DUCK, DAFFY
004,44,88,25,MOUSE, JERRY
I am only working with the first column master_account_number and the 4th column cur.
I want to check for duplicates of the"master_account_number" column, if found then add the totals up from the 4th column "cur" for only those dupes found and then do a combine for any rows that we just did a sum on. The summed value from the dupes should replace the cur value in our combined row.
With that said, our out-put should look like so.
master_account_number,sub,txn,cur,last,first
001,12,35,150.35,BIRD, BIG
002,56,9,30.50,BUNNY, BUGS
003,54,7,250,DUCK, DAFFY
004,44,88,25,MOUSE, JERRY
Now that we have that out the way, here is how this question differs. I want to keep all 42 columns intact in the out-put file. In the other question I referenced above, the input was 5 columns and the out-put was 4 columns and this is not what I'm trying to achieve. I have so many more headers, I'd hate to have specify individually all 42 columns. That seems inefficient anyhow.
As for what I have so far for code... not much.
$revNB = "\\server\path\example.csv"
$global:revCSV = import-csv -Path $revNB | ? {$_.is_active -eq "Y"}
$dupesGrouped = $revCSV | Group-Object master_account_number | Select-Object #{Expression={ ($_.Group|Measure-Object cur -Sum).Sum }}
Ultimately I want the output to look identical to the input, only the output should merge duplicate account numbers rows, and add all the "cur" values, where the merged row contains the sum of the grouped cur values, in the cur field.
Last Update: Tried Rich's solution and got an error. Modified what he had to this $dupesGrouped = $revCSV | Group-Object master_account_number | Select-Object Name, #{Name='curSum'; Expression={ ($_.Group | Measure-Object cur -Sum).Sum}}
And this gets me exactly what my own code got me so I am still looking for a solution. I need to output this CSV with all 42 headers. Even for items with no duplicates.
Other things I've tried:
This doesn't give me the data I need in the columns, the columns are there but they are blank.
$dupesGrouped = $revCSV | Group-Object master_account_number | Select-Object #{ expression={$_.Name}; label='master_account_number' },
sub_account_number,
charge_txn,
#{Name='current_balance'; Expression={ ($_.Group | Measure-Object current_balance -Sum).Sum },
last,
}

Answer 1

You're pretty close, but you used current_balance where you probably meant cur.
Here's a start:
$dupesGrouped = $revCSV | Group-Object master_account_number |
Select-Object Name, #{N='curSum'; E={ ($_.Group | Measure-Object cur -Sum).Sum},
#{N='last'; E={ ($_.Group | Select-Object last -first 1).last} }
You can add the other fields by adding Name;Expression hashtables for each of the fields you want to summarize. I assumed you would want to select the first occurrence of repeated last name for the same master_account_number. The output will be incorrect if the last name differs for the same master_account_number.

Answer 2

In the case of changing only part of the data, there is also the following way.
$dupesGrouped = $revCSV | Group-Object master_account_number | ForEach-Object {
# copy the first data in order not to change original data
$new = $_.Group[0].psobject.Copy()
# update the value of cur property
$new.cur = ($_.Group | Measure-Object cur -Sum).Sum
# output
$new
}