**Operator Type:**

**Operator Scope of Action:**

**Operator Purpose:**

**Operator First Added:**

**Operator Last Altered:**

**Operator Uses Regular Expressions:**

**Operator Has Conditional Arguments:**

**Operator Has Newer Dot-Operator Variant:**

Function [other Function type actions]

Conditional Group [operators of similar scope]

Mathematical [other Mathematical operators]

Baseline

As at baseline

[More on regular expressions in Tinderbox]

[More on scoped arguments in Action Code]

[More on conditional operator arguments]

Yes

**sum_if(scope, condition, expressionStr)**

This computes the Number sum of every **expressionStr** value in each **scope** item (defining **scope**), as filtered by a **condition** expression. See sum() for a related non-conditional operator.

**scope **describes the notes to be examined and may be any group designator including a find() query. sum_if() omits notes for which $Searchable is false.

In addition, where may be argument that designates a particular (single) note other than this.

**condition** is action code forming a valid conditional query test, i.e. it equates to `true`

when matched. Some query-style operators terms may allow use of regular expressions.

**expressionStr** can be an expression, but is typically a Number-attribute value or a List/Set holding a list of numbers. It can also be a literal number 1, i.e. if the test is `true`

from that item then add one to the retuned value of sum_if().

For example,

`$MyNumber = sum_if(children,$Prototype=="p_Problem",1);`

sums the number of children of the current note whose prototype is 'p_Prototype'. If tested value is a string with spaces, e.g. "p Prototype" vs. "p_Prototype" then use double quotes around the value.

The newer count_if() offers a more intuitive method of counting matches rather than the value of matched items.