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Fills

The area between any two plots can be filled with a color (often semi-transparent). To use this feature there is a @plot.fill decorator and a plot.Fill class. In the first place the @plot.fill decorator declares which two plots should be used for filling. Optionally it may have a color argument, which should be used if a single-colored fill is desired.

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Single-colored fill

The simplest possible use case fills the space between two plot lines: 
# indie:lang_version = 5
from indie import indicator, color, plot

@indicator('Example 1', overlay_main_pane=True)
@plot.line('p1')
@plot.line('p2')
@plot.fill('p1', 'p2', color=color.BLUE(0.2))
def Main(self):
    a = self.high
    b = self.low
    return a[0], b[0], plot.Fill()
Figure 8.1. Single-colored fill. Please note that both @plot.fill decorator and plot.Fill object always must be used together. Even in simple cases of a single-colored fill where the plot.Fill object is constructed with all default values (i.e. with no arguments plot.Fill()). This is because @plot.fill occupies one output slot in the return tuple, the same way @plot.line or @plot.marker do. Unlike @level and @band, which are purely static decorators and require no return value, each @plot.fill must have a corresponding plot.Fill() in the return. This also means that plot.Fill(color=c) can override the static color from the decorator per bar, as shown in the “Multicolored fill” section below.

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Multicolored fill

If a multicolored fill is needed, then the color value should be calculated in the Main function code and passed as argument to a plot.Fill object returned by the Main function. 
# indie:lang_version = 5
from indie import indicator, color, plot

@indicator('Example 2', overlay_main_pane=True)
@plot.line('p1')
@plot.line('p2')
@plot.fill('p1', 'p2')
def Main(self):
    c = color.GREEN(0.5) if self.close[0] > self.open[0] else color.RED(0.5)
    return self.high[0], self.low[0], plot.Fill(color=c)  # NOTE: This color will override color in @plot.fill decorator if any
Figure 8.2. Multi-colored fill.

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Multicolored fill with an offset

plot.Fill() has an optional parameter offset: int. It may be used to shift the coloring to the left (if offset is negative) or to the right (if offset is positive): 
# indie:lang_version = 5
from indie import indicator, color, plot, param

@indicator('Example 3', overlay_main_pane=True)
@plot.line('p1')
@plot.line('p2')
@plot.fill('p1', 'p2')
@param.int('fill_offset', default=2)
def Main(self, fill_offset):
    c = color.GREEN(0.5) if self.close[0] > self.open[0] else color.RED(0.5)
    return self.high[0], self.low[0], plot.Fill(color=c, offset=fill_offset)
Please note that a non-zero fill offset only affects multi-color fills and has no effect on single-color ones.

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Fill combined with markers

When using @plot.fill alongside @plot.marker, each decorator needs its own return value. Count all @plot.* decorators — the return tuple must have the same number of items. 
# indie:lang_version = 5
from indie import indicator, color, plot
from indie.algorithms import Rsi

@indicator('RSI with Fill and Signal')
@plot.line(id='rsi',  color=color.AQUA,                 title='RSI')
@plot.line(id='ob',   color=color.rgba(255,80,80,0.6),  title='Overbought')
@plot.line(id='os',   color=color.rgba(80,200,80,0.6),  title='Oversold')
@plot.fill('ob', 'os', color=color.rgba(100,100,200,0.1), title='Neutral Zone')
@plot.marker(style=plot.marker_style.CIRCLE, position=plot.marker_position.BELOW, size=5, title='Buy Signal')
def Main(self):
    rsi_val = Rsi.new(self.close, 14)[0]

    fill_color = color.rgba(255,100,100,0.2) if rsi_val >= 70 else (
        color.rgba(100,255,100,0.2) if rsi_val <= 30 else color.rgba(100,100,200,0.1)
    )
    buy_color = color.GREEN if rsi_val <= 30 else color.rgba(0,0,0,0)

    # 5 decorators → 5 return values: rsi, ob, os, fill, marker
    return rsi_val, 70.0, 30.0, plot.Fill(color=fill_color), plot.Marker(value=rsi_val, color=buy_color)

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Levels

@level() decorator creates a level (horizontal line). 
@level(
  value: float,
  title: indie.Optional[str] = None,
  line_color: indie.Color = indie.color.GRAY(0.5),
  line_style: int = indie.line_style.DASHED,
  line_width: int = 1
) -> NoneType
Parameters:
  • value — Value of the level on the indicator’s vertical scale
  • title — Human-readable title which is visible in the indicator’s Settings panel.
  • line_color — Color of the line.
  • line_style — Style of the line. It is represented as enum value of type line_style.
  • line_width — Width of the line.
Example: 
# indie:lang_version = 5
from indie import indicator, level, color

@indicator('Level example')
@level(150, line_color=color.RED, line_width=4)
def Main(self):
    return self.close[0]
Figure 8.3. Example of an indicator with @level.

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Bands

@band() decorator creates a band (two horizontal lines usually with a semi-transparent fill in between them). 
@band(
  value1: float,
  value2: float,
  title: indie.Optional[str] = None,
  fill_color: indie.Color = indie.color.GREEN(0.05),
  line_color: indie.Color = indie.color.GRAY(0.5),
  line_style: int = indie.line_style.DASHED,
  line_width: int = 1
) -> NoneType
Parameters:
  • value1 — Value of the first horizontal line of a band on a vertical scale of an indicator.
  • value2 — Value of the second horizontal line of a band on a vertical scale of an indicator.
  • title — Human-readable title which is visible in the indicator’s Settings panel.
  • fill_color — Color of the background.
  • line_color — Color of the line.
  • line_style — Style of the line. It is represented as enum value of type line_style.
  • line_width — Width of the line.
Example: 
# indie:lang_version = 5
from indie import indicator, band, color

@indicator('Band example')
@band(145, 155, line_color=color.RED, line_width=4)
def Main(self):
    return self.close[0]
Figure 8.4. Example of an indicator with @band.