Question

I am a new user in powershell. I have like 30 files with the similar data set with three columns. The columns data are Lat Long Value. It also has a header as shown below. However, the columns are not labeled.

The sample data looks like this :

* , Water Column, Depth Averaged
   437416.450  3350091.975        0.000
   437379.500  3350133.550        0.000
   437583.925  3350278.375        0.000
   437545.475  3350312.800        0.000
   437768.700  3350492.125        0.000
   437730.675  3350525.050        0.000
   437919.750  3350668.850        0.000
   437883.350  3350701.150        0.000
   438072.475  3350836.850        0.000
   438039.500  3350871.075        0.000
   438221.250  3350960.400        0.000
   438189.300  3351005.500        0.000
   438381.025  3351048.025        0.000
   438346.900  3351107.250        0.000
   438588.600  3351155.800        0.000
   438548.000  3351225.825        0.000
   438802.400  3351278.925        0.002
   438753.750  3351354.150        0.001
   439000.525  3351414.850        0.013
   438946.625  3351488.475        0.009
   439181.000  3351557.950        0.064
   439126.725  3351626.025        0.048
   439361.600  3351708.700        0.277
   439308.550  3351773.525        0.227

I want to calculate the average of value of each row from all the files in the same folder. Basically, the first row will have an average of 30 data points from 30 files. I thought powershell might be able to do with a simple algorithm.

I found a similar post calculating average using awk from multiple files on stackoverflow but I couldn’t understand how it is implemented.

Could anyone help me understand how Powershell actually calculate the average from the same column in muliple files ? I want to create a new file with the similar columns; Lat Long and Average.

Thanks

Jdbaba

Answer 1

there are surely more efficient ways but here is one :

$results=@{}

#assuming your files are tab delimited and named position1.csv, position2.csv ...:
ls c:\temp\position*.csv | foreach
    {
    get-content $_.fullname | foreach
    {
        $slices=$_.split("`t")
        #verify we have our 3 columns
        if( $slices.count -eq 3)
        {
            #create an hash table with latitude-longitude as key
            $key=$slices[0]+"-"+$slices[1]

            if( $results.count -ne 0 -and $results.GetEnumerator().name -contains $key ) {
                $results[$key]+=$slices[2]
            }
            else{
                $results[$key]=@($slices[2])
            }
        }
    }
}

$results.GetEnumerator().name |%{
   "{0}`t{1}`t{2}" -f ($_.split("-")[0]) , ($_.split("-")[1]) , ($results[$_] | Measure-Object -Average).Average
}