pipe separated category groups

in EE2 I am trying to display a list of categories in a certain group then a pipe | then a list of categories in the next group then a PIPE | with no luck. I am getting pipes even when no category group exists. How can I only show the PIPE if the group is being used?

{exp:channel:entries channel="portal" limit="1" paginate="bottom" dynamic_parameters="category" dynamic="yes"}

{title}

{categories show_group="1" }{category_name}, {/categories} {categories show_group="2" }{if category_count >= 1} | {/if} {category_name}, {/categories} {categories show_group="4" }{if category_count >= 1} | {/if} {category_name}, {/categories} {categories show_group="5" }{if category_count >= 1} | {/if} {category_name}, {/categories} {categories show_group="6" }{if category_count >= 1} | {/if} {category_name}, {/categories} {categories show_group="7" }{if category_count >= 1} | {/if} {category_name}, {/categories}

<hr> {/exp:channel:entries}