Getting a constant value from a series

问题

I want to assign a constant value to a variable. This value comes from a series. The value is 10 bars back, and must stay constant unless there is a new bar.

I tried this code and lots of variations on it, but it didn't work.

//@version=4
study(title = "X", overlay = false)

var x = 0.0
x := valuewhen(barstate.islast, sum(cht_acum[10], 10), 1)

plot(x, title = "X")

I don't get a straight line, or I get NA. How to resolve the issue?

回答1:

Version 1

Hard to figure out what you want. This may come close. You can use the Inputs to plot only on the last bar:

//@version=4
study(title = "X", overlay = false)
cht_acum = close
plotOnLastBarOnly = input(false)
x = sum(cht_acum[10], 10)
plot(barstate.islast or not plotOnLastBarOnly ? x : na, title = "X")

Version 2

This version uses the brilliant Sum() function from alexgrover found in Functions Allowing Series As Length - PineCoders FAQ, which accepts a series length. Should be closer to your needs:

//@version=4
study("")
Sum(src,p) => a = cum(src), a - a[max(p,0)]
cond = rising(close, 30)
sourceSeries = 1.
var count = 0.
if cond
    count := 1.
else
    count := min(10, count + 1)
total = Sum(sourceSeries, count)
plot(total)
plotchar(cond, "cond", "•", location.top, size = size.tiny)

来源：https://stackoverflow.com/questions/62052149/getting-a-constant-value-from-a-series