pyaf: Projections Wrongfully Linear

I am training a basic model that is comparing weight lifted vs. time.

As you will notice, the timeline is pretty limited, but this will likely be the case in most of my uses. The visual (shown below) is linear, which is obviously incorrect.

I am not too advanced in Python or forecasting, but visually, something looks wrong. Here is my full code, which includes data:

import pandas as pd
import ssl
import datetime
import matplotlib.pyplot as plt
import pyaf.ForecastEngine as autof
import numpy

temp_data = [
	
	
	{
		"weight" : 185.0,
		"date" : "2021-11-19"
	},
	{
		"weight" : 165.0,
		"date" : "2021-11-22"
	},
	{
		"weight" : 145.0,
		"date" : "2021-11-28"
	},
	{
		"weight" : 175.0,
		"date" : "2021-12-01"
	},
	
	{
		"weight" : 145.0,
		"date" : "2021-12-08"
	},
	{
		"weight" : 150.0,
		"date" : "2021-12-12"
	},
	{
		"weight" : 190.0,
		"date" : "2021-12-18"
	},
	{
		"weight" : 200.0,
		"date" : "2021-12-24"
	},
	{
		"weight" : 180.0,
		"date" : "2021-12-27"
	},
	{
		"weight" : 175.0,
		"date" : "2022-01-01"
	},
	{
		"weight" : 160.0,
		"date" : "2022-01-05"
	},
]

#data = numpy.toarray(temp_data)

if __name__ == '__main__':
	weight_dataframe = pd.DataFrame(temp_data)
	print(weight_dataframe)
	weight_dataframe['date'] = weight_dataframe['date'].apply(lambda x : datetime.datetime.strptime(x, "%Y-%m-%d"))
	weight_dataframe.head()

	lEngine = autof.cForecastEngine();
	lEngine.train(weight_dataframe , 'date' , 'weight', 50);
	weight_forecast_dataframe = lEngine.forecast(weight_dataframe, 50);
	lEngine.getModelInfo() # => relative error 7% (MAPE)

	#print(weight_forecast_dataframe)
	weight_forecast_dataframe.plot.line('date', ['weight', 'weight_Forecast_Upper_Bound', 'weight_Forecast_Quantile_50', 'weight_Forecast_Lower_Bound'], grid = True, figsize=(12, 8), marker = 'o', color = ['#A1A5FF', 'green', 'blue', 'red'], title = 'Bench Press Projections');
	plt.legend(['Previous Weight', 'Max Projected Weight', 'Median Projected Weight', 'Min Projected Weight'])
	plt.ylabel('Weight')
	plt.xlabel('Date')
	plt.show()

Here is a visual output:

Here is my system info as requested:

/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/_distutils_hack/init.py:33: UserWarning: Setuptools is replacing distutils. warnings.warn(“Setuptools is replacing distutils.”) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘Cython_version’, ‘NOT_INSTALLED’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘dill_version’, ‘0.3.6’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘keras_version’, ‘NOT_INSTALLED’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘lightgbm_version’, ‘NOT_INSTALLED’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘matplotlib_version’, ‘3.6.2’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘numpy_version’, ‘1.23.5’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘pandas_version’, ‘1.5.2’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘pathos_version’, ‘NOT_INSTALLED’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘pip_version’, ‘22.3’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘pyaf_version’, ‘4.0’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘pydot_version’, ‘1.4.2’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘python_implementation’, ‘CPython’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘python_version’, ‘3.11.0’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘scipy_version’, ‘1.9.3’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘setuptools_version’, ‘65.5.0’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘sklearn_version’, ‘1.1.3’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘skorch_version’, ‘NOT_INSTALLED’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘sqlalchemy_version’, ‘1.4.44’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘system_platform’, ‘macOS-12.5-arm64-arm-64bit’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘system_processor’, ‘arm’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘system_uname’, uname_result(system=‘Darwin’, node=‘MacBook-Pro.local’, release=‘21.6.0’, version=‘Darwin Kernel Version 21.6.0: Sat Jun 18 17:07:22 PDT 2022; root:xnu-8020.140.41~1/RELEASE_ARM64_T6000’, machine=‘arm64’)) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘torch_version’, ‘NOT_INSTALLED’) PYAF_SYSTEM_DEPENDENT_VERSION_INFO (‘xgboost_version’, ‘1.7.1’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘COLORTERM’, ‘truecolor’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘COMMAND_MODE’, ‘unix2003’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘GIT_ASKPASS’, ‘/private/var/folders/_v/tdvwxstj3ljd7x9hdh16s8kc0000gn/T/AppTranslocation/98905D2F-13A3-4069-B8FB-27DEDF170F99/d/Visual Studio Code.app/Contents/Resources/app/extensions/git/dist/askpass.sh’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘HOME’, ‘/Users/brandonjakobson’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘KMP_DUPLICATE_LIB_OK’, ‘True’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘KMP_INIT_AT_FORK’, ‘FALSE’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘LANG’, ‘en_US.UTF-8’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘LOGNAME’, ‘brandonjakobson’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘MallocNanoZone’, ‘0’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘OLDPWD’, ‘/Users/brandonjakobson/Downloads/WorkoutProjections’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘ORIGINAL_XDG_CURRENT_DESKTOP’, ‘undefined’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘PATH’, ‘/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Applications/VMware’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘PWD’, ‘/Users/brandonjakobson/Downloads/WorkoutProjections’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘SHELL’, ‘/bin/zsh’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘SHLVL’, ‘1’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘SSH_AUTH_SOCK’, ‘/private/tmp/com.apple.launchd.vZZcYkY6Qx/Listeners’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘TERM’, ‘xterm-256color’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘TERM_PROGRAM’, ‘vscode’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘TERM_PROGRAM_VERSION’, ‘1.73.0’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘TMPDIR’, ‘/var/folders/_v/tdvwxstj3ljd7x9hdh16s8kc0000gn/T/’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘USER’, ‘brandonjakobson’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘USER_ZDOTDIR’, ‘/Users/brandonjakobson’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘VSCODE_GIT_ASKPASS_EXTRA_ARGS’, ‘–ms-enable-electron-run-as-node’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘VSCODE_GIT_ASKPASS_MAIN’, ‘/private/var/folders/_v/tdvwxstj3ljd7x9hdh16s8kc0000gn/T/AppTranslocation/98905D2F-13A3-4069-B8FB-27DEDF170F99/d/Visual Studio Code.app/Contents/Resources/app/extensions/git/dist/askpass-main.js’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘VSCODE_GIT_ASKPASS_NODE’, ‘/private/var/folders/_v/tdvwxstj3ljd7x9hdh16s8kc0000gn/T/AppTranslocation/98905D2F-13A3-4069-B8FB-27DEDF170F99/d/Visual Studio Code.app/Contents/Frameworks/Code Helper.app/Contents/MacOS/Code Helper’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘VSCODE_GIT_IPC_HANDLE’, ‘/var/folders/v/tdvwxstj3ljd7x9hdh16s8kc0000gn/T/vscode-git-810feb144a.sock’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘VSCODE_INJECTION’, ‘1’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘XPC_FLAGS’, ‘0x0’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘XPC_SERVICE_NAME’, ‘0’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘ZDOTDIR’, ‘/Users/brandonjakobson’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE ('’, ‘/usr/local/bin/python3’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘__CFBundleIdentifier’, ‘com.microsoft.VSCode’) PYAF_SYSTEM_DEPENDENT_ENVIRONMENT_VARIABLE (‘__CF_USER_TEXT_ENCODING’, ‘0x1F5:0x0:0x0’)