How to deal with "distorted" array-output - arrays

I'm trying to build a "connect four" in powershell, usable via console commands, without any GUI.
I've written the code to initialize the gamefield via the output of an array. However, after the newline element in the array, after the very first line, the output gets moved a little to the left:
The code i'm using that produces the error:
$initializegamefield = #()
$savedgamefield = #()
for ($i = 0; $i -lt 48; $i++) {
if (($i -eq 7 ) -or ($i -eq 15) -or ($i -eq 23) -or ($i -eq 31) -or ($i -eq 39) -or ($i -eq 47)) {
$initializegamefield += "`n"
Write-Host "$($initializegamefield)"
$savedgamefield += $initializegamefield
$initializegamefield = #()
} else {
$initializegamefield += "A"
}
}
#Write-Host "$($initializegamefield)"
Write-Host "$($savedgamefield)"
Here I've basically initialized the gamefield two times for testing purposes.
The first time it is initialized, it is done via outputting the array $initializegamefield after it has been filled with ONE ROW including the newline element.
Afterwards $initializegamefield is emptied (see if structure).
In addition, before it is emptied, it is saved to $savedgamefield.
Whilst the formatting of the gamefield is okay with the way I do it with $initializegamefield it isn't okay anymore when doing it it with $savedgamefield.
How can I avoid having this distortion of $savedgamefield?

Since your game field is a 6x8 array I'd recommend actually initializing it as an 6x8 array:
$height = 6
$width = 8
$gamefield = New-Object 'Object[,]' $height, $width
for ($i=0; $i -lt $height; $i++) {
for ($j=0; $j -lt $width; $j++) {
$gamefield[$i, $j] = 'A'
}
}
or at least as a "jagged" array (an array of arrays):
$height = 6
$width = 8
$gamefield = #()
for ($i=0; $i -lt $height; $i++) {
$gamefield += ,#(1..$width | ForEach-Object { 'A' })
}

Related

how to create bunch of arrays inside a loop in powershell

I'm writing a script to fetch values for a set of components and storing the fetched values in an array. As there are many components I created a loop and tried to create an array name along with its iteration value (fi1, fi2, fi3, etc.) like this.
Here is the code:
function fiswitchinfo {
Param ($sheet, [string]$text, $iter)
$($fi+($iter)) = #()
$max = $sheet.UsedRange.Rows.Count
for ($i=1; $i -lt 900 ; $i++) {
$rows = $sheet.Cells.Item($i, 2).EntireRow
$cell_info = $sheet.Cells.Item($i, 2)
$cell = $cell_info.Address($false, $false)
if ($rows.hidden -eq $false) {
$cell_info = $sheet.Cells.Item($i, 2).Text
if ($cell_info -ne "" -and $cell_info.Contains($text) -eq "True") {
$cell = $cell -split "(?<=[A-Z])(?=\d)"
[int]$curline = $cell[1]
$component = $sheet.Cells.Item($curline, 2).Text
$compip = $sheet.Cells.Item($curline, 3).Text
$row = $sheet.Cells.Item($curline, 2).EntireRow
$cellinfo = $sheet.Cells.Item($curline, 2).text
if ($row.Hidden -ne "True" -and $cellinfo -ne $null) {
Write-Host $component $compip
$script:fi+$iter += $compip
}
}
}
}
}
fiswitchinfo $worksheet_3 "Fabric Interconnect 01 Cluster IP" 1
fiswitchinfo $worksheet_3 "Fabric Interconnect 01 A" 1
fiswitchinfo $worksheet_3 "Fabric Interconnect 01 B" 1
I'm not quite sure what you expect $($fi+($iter)) or $script:fi+$iter to do, but I'm pretty certain they won't do whatever it is you expect.
To have a function create an array of arrays in a loop and then return it you'd do something like this:
function fiswitchinfo {
...
$arr = #()
for ($i=1; $i -lt 900 ; $i++) {
...
$arr += ,$compip
}
return ,$arr
}
$fi1 = fiswitchinfo ...
$fi2 = fiswitchinfo ...
...
The leading comma in the statements $arr += ,$compip and return ,$arr is the unary array construction operator, which prevents PowerShell from unrolling the arrays. $arr += ,$compip appends $compip to $arr as a nested array (thus making $arr a jagged array) instead of appending the elements of $compip to $arr. return ,$arr ensures that $arr is returned to the caller as-is (thus preserving the array even if it's empty).

Powershell how to process a variable array

I have the following situation in powershell:
$arrayX = 0..1
$arrayY = 0..10
$array1 = #()
$array2 = #()
for ($i = 0; $i -lt $arrayY.Length; $i++){
$array1 += $arrayX[0] + $arrayY[$i]
$array2 += $arrayX[1] + $arrayY[$i]
}
Both $arrayX and $arrayY can be variable in length. If i extend $arrayX by 1 i'll need to adjust the code to take the third value into account. like this:
$arrayX = 0..2
$arrayY = 0..10
$array1 = #()
$array2 = #()
$array3 = #()
for ($i = 0; $i -lt $arrayY.Length; $i++){
$array1 += $arrayX[0] + $arrayY[$i]
$array2 += $arrayX[1] + $arrayY[$i]
$array3 += $arrayX[2] + $arrayY[$i]
}
What is the best practice in a situation like this to have this work automatic?
First, please consider not using the += operation with arrays: it will hurt performance a lot on larger arrays. Since you know the array size in advance you can allocate all required memory in advance:
$array1 = New-Object object[] $arrayY.Length
(you may want to use more specific type instead of object: int or float/double will work)
Next, instead of assigning each array to a variable, you can instead create array of arrays:
$arrayX = 0..2
$arrayY = 0..10
$resultArrays = New-Object int[][] $arrayX.Length
for ($x = 0; $x -lt $resultArrays.Length; ++$x)
{
$resultArrays[$x] = New-Object int[] $arrayY.Length
}
for ($y = 0; $y -lt $arrayY.Length; ++$y)
{
for ($x = 0; $x -lt $arrayX.Length; ++$x)
{
$resultArrays[$x][$y] = $arrayX[$x] + $arrayY[$y];
}
}
for ($x = 0; $x -lt $resultArrays.Length; ++$x)
{
Write-Output "array $($x): $($resultArrays[$x] -join ' ')"
}
Is this what you are looking for?
$arrayX = 0..2
$arrayY = 0..10
$arrayX | ForEach-Object {
$aX = $_
New-Variable -Name ('array' + $($aX+1)) -Value ($arrayY | ForEach-Object {$_ + $aX}) -Force
}

Building a sequential string into an array (quickly)

I've written the following code to build an array with sequential strings.
It works like I expect, but I wish it ran quicker. Is there a more efficient way to produce my desired results in PowerShell?
I'm very new to PowerShell and appreciate your coaching.
$MIN = 1
$MAX = 20000
$ARRAY = #()
$PREFIX = "AA"
$startDTM = (Get-Date) # Start time
FOR ($i=$MIN; $i -le $MAX; $i++)
{
If ($i -gt 0 -and $i -lt 10) {
$ARRAY = $ARRAY + ($PREFIX+"00000"+$i)
}
If ($i -gt 9 -and $i -lt 100) {
$ARRAY = $ARRAY + ($PREFIX+"0000"+$i)
}
If ($i -gt 99 -and $i -lt 1000) {
$ARRAY = $ARRAY + ($PREFIX+"000"+$i)
}
If ($i -gt 999 -and $i -lt 10000) {
$ARRAY = $ARRAY + ($PREFIX+"00"+$i)
}
If ($i -gt 9999 -and $i -lt 100000) {
$ARRAY = $ARRAY + ($PREFIX+"0"+$i)
}
If ($i -gt 99999 -and $i -lt 1000000) {
$ARRAY = $ARRAY + ($PREFIX+$i)
}
}
$endDTM = (Get-Date) #End Time
"Elapsed Time: $(($endDTM-$startDTM).totalseconds) seconds"
$ARRAY.count #How many loaded.
Example of $ARRAY:
AA000001
AA000002
...
AA019999
AA020000
The following one-liner tooked 0.4911672 seconds (your example 12.9638944 seonds). Results are the same. It uses the format string with decimal specifier to ensure there are 6 digits and just store the result in the array:
$MIN = 1
$MAX = 20000
$PREFIX = "AA"
$ARRAY = $MIN .. $MAX | % { "$PREFIX{0:D6}" -f $_ }
You can further improove the performance by using a while loop (thanks 4c74356b41 for mentioning that):
# ....
$array = while ($MIN -le $MAX)
{
"$PREFIX{0:D6}" -f $MIN++
}
This tooked 0.0970327 seconds on my computer.

How to fill an array efficiently in Powershell

I want to fill up a dynamic array with the same integer value as fast as possible using Powershell.
The Measure-Command shows that it takes 7 seconds on my system to fill it up.
My current code (snipped) looks like:
$myArray = #()
$length = 16385
for ($i=1;$i -le $length; $i++) {$myArray += 2}
(Full code can be seen on gist.github.com or on superuser)
Consider that $length can change. But for better understanding I chose a fixed length.
Q: How do I speed up this Powershell code?
You can repeat arrays, just as you can do with strings:
$myArray = ,2 * $length
This means »Take the array with the single element 2 and repeat it $length times, yielding a new array.«.
Note that you cannot really use this to create multidimensional arrays because the following:
$some2darray = ,(,2 * 1000) * 1000
will just create 1000 references to the inner array, making them useless for manipulation. In that case you can use a hybrid strategy. I have used
$some2darray = 1..1000 | ForEach-Object { ,(,2 * 1000) }
in the past, but below performance measurements suggest that
$some2darray = foreach ($i in 1..1000) { ,(,2 * 1000) }
would be a much faster way.
Some performance measurements:
Command Average Time (ms)
------- -----------------
$a = ,2 * $length 0,135902 # my own
[int[]]$a = [System.Linq.Enumerable]::Repeat(2, $length) 7,15362 # JPBlanc
$a = foreach ($i in 1..$length) { 2 } 14,54417
[int[]]$a = -split "2 " * $length 24,867394
$a = for ($i = 0; $i -lt $length; $i++) { 2 } 45,771122 # Ansgar
$a = 1..$length | %{ 2 } 431,70304 # JPBlanc
$a = #(); for ($i = 0; $i -lt $length; $i++) { $a += 2 } 10425,79214 # original code
Taken by running each variant 50 times through Measure-Command, each with the same value for $length, and averaging the results.
Position 3 and 4 are a bit of a surprise, actually. Apparently it's much better to foreach over a range instead of using a normal for loop.
Code to generate above chart:
$length = 16384
$tests = '$a = ,2 * $length',
'[int[]]$a = [System.Linq.Enumerable]::Repeat(2, $length)',
'$a = for ($i = 0; $i -lt $length; $i++) { 2 }',
'$a = foreach ($i in 1..$length) { 2 }',
'$a = 1..$length | %{ 2 }',
'$a = #(); for ($i = 0; $i -lt $length; $i++) { $a += 2 }',
'[int[]]$a = -split "2 " * $length'
$tests | ForEach-Object {
$cmd = $_
$timings = 1..50 | ForEach-Object {
Remove-Variable i,a -ErrorAction Ignore
[GC]::Collect()
Measure-Command { Invoke-Expression $cmd }
}
[pscustomobject]#{
Command = $cmd
'Average Time (ms)' = ($timings | Measure-Object -Average TotalMilliseconds).Average
}
} | Sort-Object Ave* | Format-Table -AutoSize -Wrap
Avoid appending to an array in a loop. It's copying the existing array to a new array with each iteration. Do this instead:
$MyArray = for ($i=1; $i -le $length; $i++) { 2 }
Using PowerShell 3.0 you can use (need .NET Framework 3.5 or upper):
[int[]]$MyArray = ([System.Linq.Enumerable]::Repeat(2, 65000))
Using PowerShell 2.0
$AnArray = 1..65000 | % {2}
It is not clear what you are trying. I tried looking at your code. But, $myArray +=2 means you are just adding 2 as the element. For example, here is the output from my test code:
$myArray = #()
$length = 4
for ($i=1;$i -le $length; $i++) {
Write-Host $myArray
$myArray += 2
}
2
2 2
2 2 2
Why do you need to add 2 as the array element so many times?
If all you want is just fill the same value, try this:
$myArray = 1..$length | % { 2 }
If you need it really fast, then go with ArrayLists and Tuples:
$myArray = New-Object 'Collections.ArrayList'
$myArray = foreach($i in 1..$length) {
[tuple]::create(2)
}
and if you need to sort it later then use this (normally a bit slower):
$myArray = New-Object 'Collections.ArrayList'
foreach($i in 1..$length) {
$myArray.add(
[tuple]::create(2)
)
}
both versions are in the 20ms range for me ;-)

Print Array Elements on one line

I'm populating an array variable $array at some point in my code, for example like below
this
is
an
array
varaible
What if, I wanted to print out the array variable like thisisanarrayvariable as one liner
i took the below approach, but i'am not getting any out while the program is hanging
for ($i=0;$i -le $array.length; $i++)
{ $array[$i] }
obviuosly, i dont want to glue them together like $array[0]+$array[1]+$array[2]..
Hope i can get a better answer.
Joining array elements with no separator
Use the -join operator...
$array -join ''
...or the static String.Join method...
[String]::Join('', $array)
...or the static String.Concat method...
[String]::Concat($array)
For all of the above the result will be a new [String] instance with each element in $array concatenated together.
Fixing the for loop
Your for loop will output each element of $array individually, which will be rendered on separate lines. To fix this you can use Write-Host to write to the console, passing -NoNewline to keep the output of each iteration all on one line...
for ($i = 0; $i -lt $array.Length; $i++)
{
Write-Host -NoNewline $array[$i]
}
Write-Host
The additional invocation of Write-Host moves to a new line after the last array element is output.
If it's not console output but a new [String] instance you want you can concatenate the elements yourself in a loop...
$result = ''
for ($i = 0; $i -lt $array.Length; $i++)
{
$result += $array[$i]
}
The += operator will produce a new intermediate [String] instance for each iteration of the loop where $array[$i] is neither $null nor empty, so a [StringBuilder] is more efficient, especially if $array.Length is large...
$initialCapacity = [Int32] ($array | Measure-Object -Property 'Length' -Sum).Sum
$resultBuilder = New-Object -TypeName 'System.Text.StringBuilder' -ArgumentList $initialCapacity
for ($i = 0; $i -lt $array.Length; $i++)
{
$resultBuilder.Append($array[$i]) | Out-Null # Suppress [StringBuilder] method returning itself
}
$result = $resultBuilder.ToString()
Just use
-join $array
which will glue all elements together.

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