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update reduce examples, closes influxdata/DAR#249 (#3446)

pull/3447/head
Scott Anderson 2021-11-29 16:54:17 -07:00 committed by GitHub
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commit 86f67a8e50
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2 changed files with 61 additions and 78 deletions
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43
content/flux/v0.x/stdlib/universe/reduce.md
View File

@ -27,8 +27,8 @@ _`reduce()` is an [aggregate function](/flux/v0.x/function-types/#aggregates)._
```js
reduce(
fn: (r, accumulator) => ({ sum: r._value + accumulator.sum }),
identity: {sum: 0.0}
fn: (r, accumulator) => ({ sum: r._value + accumulator.sum }),
identity: {sum: 0.0}
)
```
@ -62,10 +62,10 @@ If the output record keys and value types do not match the `identity` keys and v
it will return a type error.
{{% /note %}}
#### r
#### r {data-type=record}
Record representing each row or record.
#### accumulator
#### accumulator {data-type=record}
Reducer record defined by [`identity`](#identity).
### identity {data-type="record"}
@ -108,9 +108,7 @@ import "sampledata"
sampledata.int()
|> reduce(
fn: (r, accumulator) => ({
sum: r._value + accumulator.sum
}),
fn: (r, accumulator) => ({sum: r._value + accumulator.sum}),
identity: {sum: 0}
)
```
@ -147,8 +145,8 @@ import "sampledata"
sampledata.int()
|> reduce(
fn: (r, accumulator) => ({
sum: r._value + accumulator.sum,
count: accumulator.count + 1
sum: r._value + accumulator.sum,
count: accumulator.count + 1,
}),
identity: {sum: 0, count: 0}
)
@ -185,9 +183,7 @@ import "sampledata"
sampledata.int()
|> reduce(
fn: (r, accumulator) => ({
prod: r._value * accumulator.prod
}),
fn: (r, accumulator) => ({prod: r._value * accumulator.prod}),
identity: {prod: 1}
)
```
@ -222,13 +218,14 @@ sampledata.int()
import "sampledata"
sampledata.int()
|> reduce(fn: (r, accumulator) => ({
count: accumulator.count + 1,
total: accumulator.total + r._value,
avg: float(v: (accumulator.total + r._value)) / float(v: accumulator.count)
}),
identity: {count: 1, total: 0, avg: 0.0}
)
|> reduce(
fn: (r, accumulator) => ({
count: accumulator.count + 1,
total: accumulator.total + r._value,
avg: float(v: (accumulator.total + r._value)) / float(v: accumulator.count + 1)
}),
identity: {count: 0, total: 0, avg: 0.0}
)
```
{{< expand-wrapper >}}
@ -245,11 +242,11 @@ sampledata.int()
##### Output data
| tag | avg | count | total |
| :-- | --: | ----: | ----: |
| t1 | 8.5 | 7 | 51 |
| t1 | 8.5 | 6 | 51 |
| tag | avg | count | total |
| :-- | ----------------: | ----: | ----: |
| t2 | 8.834 | 7 | 53 |
| tag | avg | count | total |
| :-- | ----: | ----: | ----: |
| t2 | 8.834 | 6 | 53 |
{{% /flex-content %}}
{{< /flex >}}

96
content/influxdb/v2.1/query-data/flux/custom-functions/custom-aggregate.md
View File

@ -159,23 +159,18 @@ does the same thing and is much more performant._
{{% code-tab-content %}}
```js
average = (tables=<-, outputField="average") =>
tables
average = (tables=<-, outputField="average") => tables
|> reduce(
// Define the initial accumulator record
identity: {
count: 1.0,
sum: 0.0,
avg: 0.0
},
fn: (r, accumulator) => ({
// Increment the counter on each reduce loop
count: accumulator.count + 1.0,
// Add the _value to the existing sum
sum: accumulator.sum + r._value,
// Divide the existing sum by the existing count for a new average
avg: accumulator.sum / accumulator.count
})
// Define the initial accumulator record
identity: {count: 0.0, sum: 0.0, avg: 0.0},
fn: (r, accumulator) => ({
// Increment the counter on each reduce loop
count: accumulator.count + 1.0,
// Add the _value to the existing sum
sum: accumulator.sum + r._value,
// Divide the existing sum by the existing count for a new average
avg: (accumulator.sum + r._value) / (accumulator.count + 1.0),
}),
)
// Drop the sum and the count columns since they are no longer needed
|> drop(columns: ["sum", "count"])
@ -189,21 +184,16 @@ average = (tables=<-, outputField="average") =>
{{% code-tab-content %}}
```js
average = (tables=<-, outputField="average") =>
tables
average = (tables=<-, outputField="average") => tables
|> reduce(
identity: {
count: 1.0,
sum: 0.0,
avg: 0.0
},
fn: (r, accumulator) => ({
count: accumulator.count + 1.0,
sum: accumulator.sum + r._value,
avg: accumulator.sum / accumulator.count
})
identity: {count: 0.0, sum: 0.0, avg: 0.0},
fn: (r, accumulator) => ({
count: accumulator.count + 1.0,
sum: accumulator.sum + r._value,
avg: (accumulator.sum + r._value) / (accumulator.count + 1.0),
}),
)
|> drop(columns: ["sum", "count"])
|> drop(columns: ["sum", "count"])
|> set(key: "_field", value: outputField)
|> rename(columns: {avg: "_value"})
```
@ -218,23 +208,22 @@ The following function expects input tables to have `c1_value` and `c2_value`
columns and generates an average for each.
```js
multiAvg = (tables=<-) =>
tables
multiAvg = (tables=<-) => tables
|> reduce(
identity: {
count: 1.0,
c1_sum: 0.0,
c1_avg: 0.0,
c2_sum: 0.0,
c2_avg: 0.0
},
fn: (r, accumulator) => ({
count: accumulator.count + 1.0,
c1_sum: accumulator.c1_sum + r.c1_value,
c1_avg: accumulator.c1_sum / accumulator.count,
c2_sum: accumulator.c2_sum + r.c2_value,
c2_avg: accumulator.c2_sum / accumulator.count
})
identity: {
count: 1.0,
c1_sum: 0.0,
c1_avg: 0.0,
c2_sum: 0.0,
c2_avg: 0.0,
},
fn: (r, accumulator) => ({
count: accumulator.count + 1.0,
c1_sum: accumulator.c1_sum + r.c1_value,
c1_avg: accumulator.c1_sum / accumulator.count,
c2_sum: accumulator.c2_sum + r.c2_value,
c2_avg: accumulator.c2_sum / accumulator.count,
}),
)
```
@ -243,16 +232,13 @@ Use `reduce()` to create a function that aggregates gross and net profit.
This example expects `profit` and `expenses` columns in the input tables.
```js
profitSummary = (tables=<-) =>
tables
profitSummary = (tables=<-) => tables
|> reduce(
identity: {
gross: 0.0,
net: 0.0
},
fn: (r, accumulator) => ({
gross: accumulator.gross + r.profit,
net: accumulator.net + r.profit - r.expenses
})
identity: {gross: 0.0, net: 0.0},
fn: (r, accumulator) => ({
gross: accumulator.gross + r.profit,
net: accumulator.net + r.profit - r.expenses
}
)
)
```