An example trend indicator

examples/ni.py

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+# -*- coding: utf-8 -*-
+from pandas_ta.overlap import sma
+from pandas_ta.utils import get_offset, verify_series
+
+# - Standard definition of your custom indicator function (including docs)-
+
+def ni(close, length=None, centered=False, offset=None, **kwargs):
+    """
+    Example indicator ni
+    """
+    # Validate Arguments
+    length = int(length) if length and length > 0 else 20
+    close = verify_series(close, length)
+    offset = get_offset(offset)
+
+    if close is None: return
+
+    # Calculate Result
+    t = int(0.5 * length) + 1
+    ma = sma(close, length)
+
+    ni = close - ma.shift(t)
+    if centered:
+        ni = (close.shift(t) - ma).shift(-t)
+
+    # Offset
+    if offset != 0:
+        ni = ni.shift(offset)
+
+    # Handle fills
+    if "fillna" in kwargs:
+        ni.fillna(kwargs["fillna"], inplace=True)
+    if "fill_method" in kwargs:
+        ni.fillna(method=kwargs["fill_method"], inplace=True)
+
+    # Name and Categorize it
+    ni.name = f"ni_{length}"
+    ni.category = "trend"
+
+    return ni
+
+ni.__doc__ = \
+"""Example indicator (NI)
+
+Is an indicator provided solely as an example
+
+Sources:
+    https://github.com/twopirllc/pandas-ta/issues/264
+
+Calculation:
+    Default Inputs:
+        length=20, centered=False
+    SMA = Simple Moving Average
+    t = int(0.5 * length) + 1
+
+    ni = close.shift(t) - SMA(close, length)
+    if centered:
+        ni = ni.shift(-t)
+
+Args:
+    close (pd.Series): Series of 'close's
+    length (int): It's period. Default: 20
+    centered (bool): Shift the ni back by int(0.5 * length) + 1. Default: False
+    offset (int): How many periods to offset the result. Default: 0
+
+Kwargs:
+    fillna (value, optional): pd.DataFrame.fillna(value)
+    fill_method (value, optional): Type of fill method
+
+Returns:
+    pd.Series: New feature generated.
+"""
+
+# - Define a matching class method --------------------------------------------
+
+# NOTE: we need to temporarily use another name for the method than for the 
+# function to avoid a name conflict in this module. But by using the bind 
+# function below we can name it right so that doesn't really matter. 
+# Just remember to rename the method if you at a later stage decide to move it 
+# into the core.py module inside pandas_ta
+def ni_method(self, length=None, offset=None, **kwargs):
+    close = self._get_column(kwargs.pop("close", "close"))
+    result = ni(close=close, length=length, offset=offset, **kwargs)
+    return self._post_process(result, **kwargs)
+
+# - Bind the function to pandas_ta and the method to AnalysisIndicators -------
+
+from pandas_ta.custom import bind
+bind('ni', ni, ni_method)