Averages/Simple moving average: Difference between revisions
→{{header|jq}}
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[1, 1, 1.5, 2, 2.5, 3, 3.3333333333333335, 3.5714285714285716, 3.75, 3.888888888888889, 4]
[1, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5]
</pre>
=={{header|jq}}==
'''Works with jq, the C implementation of jq'''
'''Works with gojq, the Go implementation of jq'''
'''Works with jaq, the Rust implementation of jq'''
jq functions are stateless, so in this entry, sma($x) is defined
as a parameterized jq filter that takes as input the relevant state as a JSON object.
This should initially include a key named "period" specifying the period,
which may be infinite, i.e. the jq value `infinite` corresponding to positive infinity.
For example the initial call to sma/1 might look like:
<pre>
{period: infinite} | sma(100)
</pre>
Two examples are given, one with a finite and the other with an infinite period.
Both compute the average of the 11 numbers 0, 1, ... 10, by calling sma(0) and then sma(1), and so on.
<syntaxhighlight lang="jq">
# The input should be a JSON object with a key named "period".
# The output is a JSON object with a key named "average" giving the SMA.
def sma($x):
def average:
.n as $n
| if $n == null or $n == 0 then . + {n: 1, average: $x}
else .average |= (. * $n + $x) / ($n + 1)
| .n += 1
end;
if . == null or (.period and .period < 1)
then "The initial call to sma/1 must specify the period properly" | error
elif .n and .n < 0 then "Invalid value of .n" | error
elif (.period | isinfinite) then average
elif .n == null or .n == 0 then . + {n: 1, average: $x, array: [$x]}
else .n as $n
| if $n < .period
then .array += [$x]
| .n += 1
else .array |= .[1:] + [$x]
end
| .average = (.array | (add/length))
end;
# Call sma($x) for the 11 numbers 0, 1, ... 10.
def example($period):
reduce range(0;11) as $x({period: $period}; sma($x))
| .average ;
example(11), example(infinite)
</syntaxhighlight>
{{output}}
<pre>
5
5
</pre>
| |||