powershell extracting data from strings or other suggestions - powershell

Question

I have a script I am writing that essentially reads data from an excel document that is generated from another tool. It lists file ages in the format listed below. My issue is I would like to process each cell value and change the cell color based on that value. So anything older than 1 year gets changed to RED, 90+ days gets yellow\orange.
So after a bit of research, I elected to use an if statement to determine when it is greater than 0 years which seems to work fine, however when I reach the days portion I'm not sure how to extract JUST the digits portion to the left of d in each cell when you get to the y if its there just stop OR possibly just read the left digits only if the $_ contains d then I could further process if that value is -gt 90? I am unsure of how to extract variable length strings only if they are digits left of a character. I considered using a combination of the below method of finding a character and returning up to y or something else.
Find character position and update file name
Possible Age Formats:
13y170d
3y249d
8h7m
1y109d
1y109d
1y109d
5d22h
3y281d
3y184d
11y263d
7m25s
1h14m
[regex]$years = "\d{1,3}[0-9]y"
[regex]$days_90 = "\d{0,3}[0-9]d"
conditionally formatting/coloring row based on age (years)
if ( $( A$_ -match "$years") -eq $True ) {
$($test_home).$("Last Accessed") | ForEach-Object { $( $($_.Contains("y") -eq $True ) { New-ConditionalText -Text Red } }
conditionally formatting/coloring row based on age (90+ days)
if ( $( A$_ -match "$days_90") -eq $True ) { New-ConditionalText -Text Yellow }

Answer 1

What you are after is a positive lookahead and lookbehind. Effectivly it gets the text between two characters or sets. Really handy if you have a consistently formatted set of data to work with.
[regex]$days_90 = '(?<=y).*?(?=d)'
. Matches any characters without line breaks.
* Matches 0 or more of the preceding token.
? Makes the regex lazy and try to match as few as possible.