TypeDB•15h ago

Reducing with 0 when value is not there

question for the non-existent values: when we sum over an attribute, say payment and for some records that this value is non-existent (which i believe typedb doesn't create any instance of that attribute for that particular entity?), how can i set 0 for those cases in my sum? I don't care about my entity just in my sum i want to replace n/e with 0. here is a query, where $pa could be non-existent for some records:

match
$p isa payment_detail,
has loan_id $li,
has payment_amount $pa;
reduce $payments = sum($pa) groupby $li;
sort $li;

match
$p isa payment_detail,
has loan_id $li,
has payment_amount $pa;
reduce $payments = sum($pa) groupby $li;
sort $li;

(originally from @Reza )

3 Replies

JoshuaOP•15h ago

@Reza sneak peak preview of optionals coming in 3.7.0 - but already available in the match patterns in 3.5.x (undocumented until fully implemented):

match
$p isa payment_detail,
has loan_id $li;
try { 
  $p has payment_amount $pa;
};
reduce $payments = sum($pa) groupby $li;
sort $li;

match
$p isa payment_detail,
has loan_id $li;
try { 
  $p has payment_amount $pa;
};
reduce $payments = sum($pa) groupby $li;
sort $li;

try that, im not entirely sure how stable it is since we added tests for it for the next major release

Reza•14h ago

thanks josh at least i didn't get any syntax error 🙂 does that ignore non-existent values or set it to 0? i don't want them to be ignored

JoshuaOP•14h ago

try running

match
$p isa payment_detail,
has loan_id $li;
try { 
  $p has payment_amount $pa;
};

match
$p isa payment_detail,
has loan_id $li;
try { 
  $p has payment_amount $pa;
};

$pa will be None when not present, which in reduce is treated as 0

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Reducing with 0 when value is not there

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