StockChartingDash/indicators.py

769 lines
25 KiB
Python

# -*- coding: utf-8 -*-
"""
TODO: given a list of symbols, for each stock, plot
Subplot1:
1. price
2. 50 and 200 day SMA lines
3. bollinger band (200 day)
Subplot2
RSI
Subplot3
MACD
TODO: validate the plots with online resource
Updated on Mon Sep. 30, 2024
Use one as buy/sell trigger and verify a bag of indicators to make final decision.
Could also come up with a value that ties to the trading volume.
@author: thomwang
"""
import pandas as pd
import numpy as np
import datetime as dt
# from util import get_watchlist
from numpy.fft import fft, ifft
import scipy.signal as sig
import plotly.express as px
from plotly.subplots import make_subplots
from dash import Dash, html, dcc, callback, Output, Input, State, no_update
from waitress import serve
from flask_caching import Cache
from dash.exceptions import PreventUpdate
import dash_auth
import yahoo_fin.stock_info as si
import hashlib
from dotenv import load_dotenv
import psycopg2
import os
import sys
pd.options.mode.chained_assignment = None # default='warn'
load_dotenv()
def connect_db():
conn = None
try:
conn = psycopg2.connect(
host=os.environ['DB_PATH'],
database=os.environ['DB_NAME'],
user=os.environ['DB_USERNAME'],
password=os.environ['DB_PASSWORD'],
)
except (Exception, psycopg2.DatabaseError) as error:
print(error)
sys.exit(1)
return conn
def sql_to_dataframe(conn, query):
cursor = conn.cursor()
try:
cursor.execute(query)
except (Exception, psycopg2.DatabaseError) as error:
print(f"Error: {error}")
cursor.close()
return 1
tuples_list = cursor.fetchall()
cursor.close()
df = pd.DataFrame(tuples_list)
return df
def get_watchlist():
QUERY = '''select * from stock_watch_list'''
return sql_to_dataframe(connect_db(), QUERY)
def hash_password(password):
# Encode the password as bytes
password_bytes = password.encode('utf-8')
# Use SHA-256 hash function to create a hash object
hash_object = hashlib.sha256(password_bytes)
# Get the hexadecimal representation of the hash
password_hash = hash_object.hexdigest()
return password_hash
# def fill_missing_data(df):
# df.ffill(inplace=True)
# df.bfilln(inplace=True)
def fft_convolve(signal, window):
fft_signal = fft(signal)
fft_window = fft(window)
return ifft(fft_signal * fft_window)
def zero_pad(array, n):
"""Extends an array with zeros.
array: numpy array
n: length of result
returns: new NumPy array
"""
res = np.zeros(n)
res[: len(array)] = array
return res
def smooth(price, hsize=10, sigma=3):
"""
Parameters
----------
price : TYPE DataFrame.
DESCRIPTION - with time index and no invalid values
hsize : TYPE integer
DESCRIPTION - this adds phase delay. similar to SMA window
sigma : TYPE float
DESCRIPTION - gaussian standard deviation affects smoothness
Returns
-------
TYPE DataFrame
DESCRIPTION - smoothed price
Doesn't offer much benefit over sma. Only theoretical values. For future
different smooth functiona experiments
"""
data = price.copy()
window = sig.gaussian(M=hsize, std=sigma)
window /= window.sum()
padded = zero_pad(window, data.shape[0])
for col in data.columns:
ys = data[col].values
smooth = abs(fft_convolve(ys, padded))
smooth[0:hsize-1] = np.nan
data[col] = smooth
return data
class security:
"""
This can be a list of stocks, bonds, or otherinvestment vehicles.
price - Pandas DataFrame with datetime as index sorted to chronical order
"""
def __init__(self, sym, price, volume=None, rfr: float = 0.01, sf: float = 252.0):
"""
Parameters
----------
price : TYPE pandas.DataFrame
DESCRIPTION. historical adj. daily close prices of stocks under
consideration
volume : TYPE pandas.DataFrame
DESCRIPTION. daily trading volume. The default is none.
rfr : TYPE float, optional
DESCRIPTION. annualized risk free rate. The default is 0.01.
sf : TYPE sample frequency, optional
DESCRIPTION. The default is 252 (daily). there are 252 trading
days in a year. Monthly sampling frequency would be 12. And
weekly sampling frequenc is 52.
"""
self._symbol = sym
self._price = price
self._volume = volume
# self._symbol = price.columns.values
self._rfr = rfr
self._sf = sf
@property
def symbol(self):
return self._symbol
@symbol.setter
def symbol(self, value):
raise AttributeError('security symbol is read only')
@property
def price(self):
return self._price
@price.setter
def price(self, value):
raise AttributeError('security price is read only')
@property
def volume(self):
if self._volume is None:
raise ValueError('trading volume information not available')
return self._volume
@volume.setter
def volume(self, value):
raise AttributeError('security volume is read only')
def sma(self, window):
return self.price.rolling(window).mean()
def vwma(self, window):
"""
Volume weighted moving average. When plotted against sma, it gives an
early indicator when VWMA crosses SMA. When VWMA is above SMA, it
indicates a strong upward trend and vice versa.
"""
price_vol = self.price * self.volume
return price_vol.rolling(window).sum() / self.volume.rolling(window).sum()
def vosma(self, window):
return self.volume.rolling(window).mean()
def ema(self, window): # default to 14 day window
# EMA pre-process the first point
price = self.price
temp = price.iloc[0:window].mean()
price.iloc[window-1] = temp
price.iloc[0:(window-1)] = np.nan
# process the EMA
avg = price.ewm(span=window, adjust=False).mean()
return avg
def voema(self, window): # default to 14 day window
# EMA pre-process the first point
vol = self.volume
temp = vol.iloc[0:window].mean()
vol.iloc[window-1] = temp
vol.iloc[0:(window-1)] = np.nan
# process the EMA
avg = vol.ewm(span=window, adjust=False).mean()
return avg
def rsi(self, window = 14):
"""
Traditional interpretation and usage of the RSI are that values of 70
or above indicate that a security is becoming overbought or overvalued
and may be primed for a trend reversal or corrective pullback in price.
An RSI reading of 30 or below indicates an oversold or undervalued
condition.
"""
# use exponential averaging
d_chg = self.price.diff()
d_up, d_dn = d_chg.copy(), d_chg.copy()
d_up[d_up < 0] = 0
d_dn[d_dn > 0] = 0
# EMA pre-process the first point
temp = d_up.iloc[1:(window+1)].mean()
d_up.iloc[window] = temp
d_up.iloc[1:window] = np.nan
temp = d_dn.iloc[1:(window+1)].mean()
d_dn.iloc[window] = temp
d_dn.iloc[1:window] = np.nan
# process the EMA
avg_up = d_up.ewm(span=window, adjust=False).mean()
avg_dn = d_dn.ewm(span=window, adjust=False).mean()
rs = avg_up / abs(avg_dn.values)
exp_rsi = 100 - 100 / (1+rs)
return exp_rsi
def volume_rsi(self, window = 14):
"""
The volume RSI (Relative Strength Index) is quite similar to the price
based RSI with difference that up-volume and down-volume are used in
the RSI formula instead changes in price. If price RSI shows relation
between up-moves and down-moves within an analyzed period of time by
revealing which moves are stronger, the volume RSI indicator shows the
relation between volume traded during these price up-moves and
down-moves respectfully by revealing whether up-volume (bullish money
flow) or down-volume (bearish money flow) is stronger.
The same as price RSI, volume RSI oscillates around 50% center-line in
the range from 0 to 100%. In technical analysis this indicator could be
used in the same way as well. The simplest way of using the volume RSI
would be to generate trading signals on the crossovers of the indicator
and 50% center-line around which it oscillates. Here you have to
remember following:
volume RSI reading above 50% are considered bullish as bullish volume
dominates over bearish volume; volume RSI readings below 50% are
considered bearish as bearish volume overcomes bullish volume.
Respectfully, technical analysis would suggest to generate buy/sell
signals by following rules:
Buy when indicators moves above 50% line after being below it;
Sell when indicator drops below 50% line after being above it.
"""
# use exponential averaging
volume = self.volume
up_vol, dn_vol = volume.copy(), volume.copy()
d_chg = self.price.diff()
up_vol[d_chg < 0] = 0
dn_vol[d_chg > 0] = 0
up_vol.iloc[0] = np.nan
dn_vol.iloc[0] = np.nan
# EMA pre-process the first point
temp = up_vol.iloc[1:(window+1)].mean()
up_vol.iloc[window] = temp
up_vol.iloc[1:window] = np.nan
temp = dn_vol.iloc[1:(window+1)].mean()
dn_vol.iloc[window] = temp
dn_vol.iloc[1:window] = np.nan
# EMA processing
avg_up = up_vol.ewm(span=window, adjust=False).mean()
avg_dn = dn_vol.ewm(span=window, adjust=False).mean()
rs = avg_up / avg_dn.values
exp_rsi = 100 - 100 / (1+rs)
return exp_rsi
def daily_returns(self):
return self.price.pct_change()
@property
def annualized_return(self):
dr = self.daily_returns()
return self._sf * dr.mean()
@property
def annualized_stdev(self):
dr = self.daily_returns()
return np.sqrt(self._sf) * dr.std()
@property
def sharpe(self):
return (self.annualized_return - self._rfr) / self.annualize_stdev
def rolling_stdev(self, window):
return self.price.rolling(window).std()
def bollinger(self, window):
"""
Parameters
----------
window : TYPE int, optional
DESCRIPTION - averaging window in days.
Returns
-------
lower, upper : TYPE pandas.DataFrame
DESCRIPTION - lower band (minus 2 sigma) and the upper band.
"""
avg = self.sma(window)
sdd2 = self.rolling_stdev(window).mul(2)
lower = avg.sub(sdd2.values)
upper = avg.add(sdd2.values)
# low_up = lower.join(upper, lsuffix='_L', rsuffix='_U')
return lower, upper
def macd(self, short_wd = 12, long_wd = 26, sig_wd = 9):
"""
MACD Line: (12-day EMA - 26-day EMA)
Signal Line: 9-day EMA of MACD Line
MACD Histogram: MACD Line - Signal Line
MACD is calculated by subtracting the 26-period EMA from the 12-period
EMA. MACD triggers technical signals when it crosses above (to buy) or
below (to sell) its signal line. The speed of crossovers is also taken
as a signal of a market is overbought or oversold. MACD helps investors
understand whether the bullish or bearish movement in the price is
strengthening or weakening
MACD historgram represents signal line crossovers that are the most
common MACD signals. The signal line is a 9-day EMA of the MACD line.
As a moving average of the indicator, it trails the MACD and makes it
easier to spot MACD turns. A bullish crossover occurs when the MACD
turns up and crosses above the signal line. A bearish crossover occurs
when the MACD turns down and crosses below the signal line. Crossovers
can last a few days or a few weeks, depending on the strength of the
move.
"""
macd_short = self.ema(short_wd)
macd_long = self.ema(long_wd)
macd_line = macd_short - macd_long.values
macd_sig = macd_line.ewm(span=sig_wd, adjust=False).mean()
macd_hist = macd_line - macd_sig.values
norm_hist = macd_hist.div(macd_long.values)
return macd_line, macd_sig, macd_hist, norm_hist
def get_crossing(stocks):
"""
Parameters
----------
stocks : TYPE instance of class 'security'
Returns
-------
cross : TYPE pandas DataFrame
DESCRIPTION - +1 when 50 day moving average is above 200 day moving
average. -1 when vice versa. transition days are of value +3 and -3
respectively.
"""
sma50 = stocks.sma(50)
sma200 = stocks.sma(200)
cross = np.sign(sma50.sub(sma200.values))
cross_diff = cross.diff()
cross = cross.add(cross_diff.values)
cross.columns = stocks.price.columns
return cross
def get_sma_slope(stocks, wd = 50):
"""
Parameters
----------
stocks : TYPE
DESCRIPTION.
wd : TYPE, optional
DESCRIPTION. The default is 50.
Returns
-------
slope : TYPE pandas DataFrame
DESCRIPTION - +1 when n day moving average is positive. -1 when
negative. transition days are of value +3 and -3 respectively.
"""
sma = stocks.sma(wd)
slope = np.sign(sma.diff())
slope_diff = slope.diff()
slope = slope.add(slope_diff.values)
return slope
LB_YEAR = 3 # years of stock data to retrieve
# PLT_YEAR = 2 # number of years data to plot
LB_TRIGGER = 5 # days to lookback for triggering events
def intelligent_loop_plots(sym, stk_data):
# Only plot ones that are standing out meaning:
# 1. outside of bollinger bands or recently crossed over (within 9 days)
# 2. RSI above 70 or below 30
# 3. VoRSI above 70 or below 30
# 4. when normalized MACD hist (by dividing slower moving average) is
# above 2% or below -2%.
# 5. near golden cross or death cross
# 6. price cross (near) 200 day moving average
# 7. MACD histogram zero crossing (bullish or bearish)
# symbol = ['AMZN', 'SPY', 'GOOG', 'BAC', 'BA', 'XLE', 'CTL', 'ATVI', 'JD',\
# 'COST', 'HD', 'UBER', 'XOM', 'UAL', 'LUV', 'T', 'WMT']
price = stk_data["adjclose"]
vol = stk_data["volume"]
stk = security(sym, price, vol)
rsi = stk.rsi()
vorsi = stk.volume_rsi()
macd, macd_sig, macd_hist, norm_hist = stk.macd()
sma50 = stk.sma(50)
vwma50 = stk.vwma(50)
sma200 = stk.sma(200)
bol_low, bol_up = stk.bollinger(200)
# init
plot_indicator = "["
# print('{:5}: '.format(sym), end = '')
# RSI outside window (over bought / over sold)
rsi_tail = rsi.tail(LB_TRIGGER)
if (rsi_tail >= 70).any() or (rsi_tail <= 30).any():
# print('--RSI', end = '')
plot_indicator += 'RSI, '
# VoRSI outside window (over bought / over sold)
vorsi_tail = vorsi.tail(LB_TRIGGER)
if (vorsi_tail >= 70).any() or (vorsi_tail <= 30).any():
# print('--VoRSI', end = '')
plot_indicator += 'VoRSI, '
# Normalized MACD histogram out of 3% range
norm_hist_tail = abs(norm_hist.tail(LB_TRIGGER))
if (abs(norm_hist_tail) >= 0.02).any():
# print('--MACD/R', end = '') # outside normal range
plot_indicator += 'MACD/R, '
# MACD histogram zero crossing
macd_hist_tail = macd_hist.tail(LB_TRIGGER)
macd_hist_sign = np.sign(macd_hist_tail)
macd_hist_diff = macd_hist_sign.diff()
if (abs(macd_hist_diff) > 1).any():
# print('--MACD', end = '') # zero crossing
plot_indicator += 'MACD, '
# Stock price crosses SMA50
sma50_cross_tail = sma50.tail(LB_TRIGGER) - price.tail(LB_TRIGGER)
sma50_cross_sign = np.sign(sma50_cross_tail)
sma50_cross_diff = sma50_cross_sign.diff()
if (abs(sma50_cross_diff) > 1).any():
# print('--SMA50', end = '')
plot_indicator += 'SMA50, '
# Death cross or golden cross - SMA50 vs SMA200
sma_cross_tail = sma50.tail(LB_TRIGGER) - sma200.tail(LB_TRIGGER).values
sma_cross_sign = np.sign(sma_cross_tail)
sma_cross_diff = sma_cross_sign.diff()
if (abs(sma_cross_diff) > 1).any():
# print('--Golden/Death', end = '')
plot_indicator += 'Golden/Death, '
# Price outside bollinger band or crossing
price_tail = price.tail(LB_TRIGGER)
bol_low_tail = bol_low.tail(LB_TRIGGER)
bol_up_tail = bol_up.tail(LB_TRIGGER)
price_high = price_tail - bol_up_tail.values
price_low = price_tail - bol_low_tail.values
if (price_high >= 0).any() or (price_low <= 0).any():
# print('--Bollinger', end ='')
plot_indicator += 'Bollinger, '
# Price cross 200 day moving average
sma200_tail = sma200.tail(LB_TRIGGER)
sma200_cross = price_tail - sma200_tail.values
sma200_cross_sign = np.sign(sma200_cross)
sma200_cross_diff = sma200_cross_sign.diff()
if (abs(sma200_cross_diff) > 1).any():
# print('--SMA200', end = '')
plot_indicator += 'SMA200, '
# Large trading volume trigger
volume_tail = vol.tail(LB_TRIGGER)
vol_mean = vol.tail(50).mean()
vol_std = vol.tail(50).std()
if ((volume_tail - vol_mean - 2*vol_std) > 0).any():
# print('--HiVol', end = '')
plot_indicator += "HiVol, "
# print(f"-- {watchlist.loc[sym, 'Notes']}") # carriage return
plot_indicator += ']'
# note_field = watchlist.loc[sym, 'Notes'].strip().lower()
# if note_field != "watch" and ( note_field == "skip" or \
# plot_indicator =="[]" ):
# continue # skipping plotting to save memory and time
# plot basic price info
data = price.copy().to_frame(sym)
# to limit low bound when plotting in log scale
bol_low.loc[sma200.divide(bol_low) > bol_up.divide(sma200).mul(3)] = np.nan
data = data.join(bol_low.rename('_BOL200L'))
data = data.join(bol_up.rename('_BOL200U'))
data = data.join(sma200.rename('_SMA200'))
data = data.join(sma50.rename('_SMA50'))
data = data.join(vwma50.rename('_WVMA50'))
macd = macd.to_frame('_MACD').join(macd_sig.rename('_SIG'))
macd = macd.join(macd_hist.rename('_HIST'))
# macd.rename(columns={sym: sym+'_MACD'}, inplace=True)
rsi = rsi.to_frame('_RSI').join(vorsi.rename('_VoRSI'))
# rsi.rename(columns={sym: sym+'_RSI'}, inplace=True)
return data, vol.to_frame('_VOL'), macd, rsi, plot_indicator
VALID_USERNAME_PASSWORD_PAIRS = {
'ce16559af2caf7bb54bebd57a1602e29ada331b3356004265abeab0e568278cc':
'b4db36eb3f887ca0bc15de7feb0b41a9589b65dbd5325aedf1c76b3ee63b8871'
}
def user_login(username, password):
if VALID_USERNAME_PASSWORD_PAIRS.get(hash_password(username)) == hash_password(password):
return True
return False
# Initialize the app
app = Dash()
dash_auth.BasicAuth(
app,
# VALID_USERNAME_PASSWORD_PAIRS,
auth_func=user_login,
secret_key="MK8dyS6PyDDuEuzrmqa7dJTJZ7eH2Jkh",
)
watchlist = get_watchlist()
# symbols = watchlist.index.values.tolist()
# symbols = (watchlist.index.values + " - " + watchlist["Sub Segment"]).tolist()
symbols = (watchlist.iloc[:, 0] + " - " + watchlist.iloc[:, 1]).tolist()
CACHE_CONFIG = {'CACHE_TYPE': 'SimpleCache'}
cache = Cache()
cache.init_app(app.server, config=CACHE_CONFIG)
@cache.memoize(timeout=14400) # cache timeout set to 4 hours
def fetch_stk_data(sym, sd):
return si.get_data(sym, start_date=sd)[["adjclose", "volume"]]
# App layout
app.layout = [
html.Div([
html.Button('Reload', id="reload-button", n_clicks=0,
style={'font-size': '12px', 'width': '120px', 'display': 'inline-block', 'margin-bottom': '10px', 'margin-right': '5px', 'height':'36px', 'verticalAlign': 'top'}),
html.Div([
dcc.Dropdown(symbols, symbols[0], id='symbols_dropdown_list',),
], style={'width': '330px', 'text-align': 'center'}),
html.Button('Auto Play', id="start-button", n_clicks=0,
style={'font-size': '12px', 'width': '120px', 'display': 'inline-block', 'margin-bottom': '10px', 'margin-right': '5px', 'height':'36px', 'verticalAlign': 'top'}),
], style={'display':'flex', 'justify-content':'center'}),
dcc.Graph(
figure={},
id='controls-and-graph',
style={'height':'85vh'}
),
# dcc.Store(id="signal"),
# dcc.Store(id="dropdown_index", data='0'),
dcc.Interval(
id='interval-component',
interval=3*1000, # in milliseconds
n_intervals=0,
max_intervals=2*len(symbols),
# max_intervals=3, # for testing
disabled=True,
),
]
app.clientside_callback(
"""
function(id) {
document.addEventListener("keyup", function(event) {
if (event.key == ' ') {
document.getElementById('start-button').click()
event.stopPropogation()
}
});
return window.dash_clientside.no_update
}
""",
Output("start-button", "id"),
Input("start-button", "id")
)
# start / stop button callback
@callback(Output('interval-component', 'disabled'),
Output("start-button", "children"),
Output('symbols_dropdown_list', 'disabled'),
Input("start-button", "n_clicks"),
State("start-button", "children"),)
def start_cycle(n, value):
if n:
if value == "Pause":
return True, "Auto Play", False
else:
return False, "Pause", True
return no_update
# reload button callback
@callback(Output('symbols_dropdown_list', 'options'),
Output('interval-component', 'n_intervals'),
Input("reload-button", "n_clicks"),)
def reload_syms(n):
if n:
watchlist = get_watchlist()
# symbols = (watchlist.index.values + " - " + watchlist["Sub Segment"]).tolist()
symbols = (watchlist.iloc[:, 0] + " - " + watchlist.iloc[:, 1]).tolist()
return symbols, 0
return no_update
# interval callback
@callback(Output('symbols_dropdown_list', 'value'),
Input("interval-component", "n_intervals"),
State('symbols_dropdown_list', 'options'),
# State('dropdown-index', 'data'),
)
def cycle_syms(n, syms):
if syms:
return syms[n % len(syms)]
else:
return no_update
# dropdown callback
@callback(
Output(component_id='controls-and-graph', component_property='figure'),
# Output("dropdown-index", "data"),
Input(component_id='symbols_dropdown_list', component_property='value'),
# State('symbols_dropdown_list', 'options')
# Input(component_id='signal', component_property='data'),
)
def update_graph(col_chosen):
if not col_chosen:
raise PreventUpdate
# return no_update
sym = col_chosen.split()[0]
end_date = dt.datetime.today()
start_date = end_date - dt.timedelta(days = 365 * LB_YEAR)
# plot_sd = end_date - dt.timedelta(days = 365 * plt_year)
# plot_ed = end_date
tmp = fetch_stk_data(sym, start_date) # cached function all
data, vol, macd, rsi, plot_ind = intelligent_loop_plots(sym, tmp)
fig = make_subplots(
rows=3,
cols=1,
shared_xaxes=True,
row_heights=[0.6, 0.2, 0.2],
vertical_spacing=0.02,
specs=[[{"secondary_y": True}],[{"secondary_y": False}],[{"secondary_y": False}]],
)
price_line = px.line(
data,
x=data.index,
y=data.columns.to_list(),
)
volume_line = px.bar(
vol,
x=vol.index,
y=vol.columns.to_list(),
)
macd_line = px.line(
macd,
x=macd.index,
y=['_MACD', '_SIG'],
)
macd_neg = macd.copy()
macd_pos = macd.copy()
macd_neg[macd_neg>0] = 0
macd_pos[macd_pos<0] = 0
macd_hist_pos = px.line(
macd_pos,
x=macd_pos.index,
y=['_HIST'],
)
macd_hist_pos.update_traces(fill='tozeroy', line_color='rgba(0,100,0,0.5)', showlegend=False)
macd_hist_neg = px.line(
macd_neg,
x=macd_neg.index,
y=['_HIST'],
)
macd_hist_neg.update_traces(fill='tozeroy', line_color='rgba(100,0,0,0.5)', showlegend=False)
rsi_line = px.line(
rsi,
x=rsi.index,
y=['_RSI', '_VoRSI'],
)
fig.add_traces(price_line.data + volume_line.data, rows=1, cols=1, secondary_ys=[True, True, True, True, True, True, False])
fig.add_traces(macd_line.data + macd_hist_pos.data + macd_hist_neg.data, rows=2, cols=1)
fig.add_traces(rsi_line.data, rows=3, cols=1)
# fig.update_traces(marker_color = 'rgba(0,0,250,0.5)',
# marker_line_width = 0,
# selector=dict(type="bar"),
fig.layout.yaxis.title="Volume"
fig.layout.yaxis2.title="Price ($)"
fig.layout.yaxis2.type="log"
fig.layout.yaxis3.title="MACD"
fig.layout.yaxis4.title="RSI/VoRSI"
fig.layout.yaxis.griddash="dash"
fig.update_layout(title_text=sym+' - '+plot_ind, title_x=0.5,
margin=dict(l=30, r=20, t=50, b=20),
)
# fig.update_layout(showlegend=False)
return fig
if __name__ == "__main__":
serve(app.server, host="0.0.0.0", port=8050, threads=7) # using production quality WSGI server Waitress
# app.run(debug=True)