Get-YammerGroups.ps1

# Yammer app developer token
$token = ""

# Base Yammer API url
$yammerBaseUrl = "https://www.yammer.com/api/v1"

# Reference - Yammer Group 
#$createGroupUri = "https://www.yammer.com/api/v1/groups.json?name=Example&private=True" 

function Get-BaererToken() {
    $headers = @{ Authorization=("Bearer " + $token) }
    return $headers
}

# Get groups basic
$groupsApi = "$($yammerBaseUrl)/groups.json?page=1"
$groups = (Invoke-WebRequest -Uri $groupsApi -Method Get -Headers $headers).content | ConvertFrom-Json 
$groups | select id, name | ft