Cash, value, size, target orders, HELP T_T

[Youssef 0]

Hello everyone, the post is long but the questions very simple!

In trying to understand what cash, portfolio value, data value and position size were, I've cooked up a simple strategy : buy at this date, sale at this date.
The problem I don't understand at all what's happening.

The way I understand it, correct me If I am wrong:

-Cash: is the money I have to buy shares or contracts or whatever.
-Portfolio value: is the cash plus the value of the assets I've bought or that I am shorting, in this regard portfolio value can be smaller than cash amount
-Data value: is the value of the specific asset I am trading when I only have one asset, it can be negative if I am shorting the asset
-Position : Am I involved with the market or not ? Am I buying or selling or whatever .
-Position size : the number of shares, cryptocoins, contracts I am trading.

The strategy :

import backtrader as bt
from datetime import datetime

class shortStrat(bt.Strategy): 
    # Moving average parameters
    params = (('pfast',20),('pslow',50),)



    def __init__(self):
        self.dataclose = self.datas[0].close
        self.datahigh = self.datas[0].high
        self.datalow = self.datas[0].low
        # Order variable will contain ongoing order details/status
        self.order = None


    def log(self, txt, dt=None):
        dt = dt or self.datas[0].datetime.date(0)
        print(f'{dt.isoformat()} {txt}') 

    def notify_order(self, order):
        if order.status in [order.Submitted, order.Accepted]:
            # An active Buy/Sell order has been submitted/accepted - Nothing to do
            return

        # Check if an order has been completed
        # Attention: broker could reject order if not enough cash
        if order.status in [order.Completed]:
            if order.isbuy():
                self.log(f'BUY EXECUTED, {order.executed.price:.2f}')
            elif order.issell():
                self.log(f'SELL EXECUTED, {order.executed.price:.2f}')
            self.bar_executed = len(self) #the bar at which the order is completd I guess

        elif order.status in [order.Canceled, order.Margin, order.Rejected]:
            self.log('Order Canceled/Margin/Rejected')

        # Reset orders
        self.order = None

    def next(self):
        if self.order:
            return
        
        print('posistion : {}'.format(self.position.size))
        print('portvalue : {}'.format(self.broker.get_value()))
        print('cash : {}'.format(self.broker.get_cash()))
        print('dataval : {}'.format(self.broker.get_value([self.data])))

        # Check if we are in the market
        if not self.position:
            # We are not in the market, look for a signal to OPEN trades
            if self.datas[0].datetime.date()==datetime(2018,1,1).date() : 
                self.order = self.order_target_percent(target=1)  
        # we are in the market
        elif self.datas[0].datetime.date()==datetime(2018,1,10).date() :
            self.order = self.order_target_percent(target=-1)  

        elif self.datas[0].datetime.date()==datetime(2018,1,1).date() : 
            self.order = self.order_target_percent(target=1)  

The bot:

from strategies.crossOver import MAcrossover
import backtrader as bt
import datetime
import numpy as np
from strategies.strat import barycentreStrat
import csv
from strategies.ShortStrat import shortStrat
import pandas as pd
dateOne="1 Jan, 2017"
dateTwo="1 Jun, 2021"
symbol="BNBUSDT"
interval="1d"





cerebro = bt.Cerebro(stdstats=True,optreturn=False,maxcpus=1)#optreturn=False
data = bt.feeds.GenericCSVData(
    timeframe=bt.TimeFrame.Days,
    compression=1,
    dataname='data\crypto\ShortData.csv',
    nullvalue=0.0,
    dtformat=('%m/%d/%Y'), 
    datetime=0,
    open=1,
    high=2,
    low=3,
    close=4,
    time=-1,
    volume=-1,
    openinterest=-1 
    

)

dayData=cerebro.adddata(data)
 
cerebro.addstrategy(shortStrat)  
 



if __name__ == '__main__':
  
    cerebro.broker.set_cash(90000)
    start_portfolio_value = cerebro.broker.getvalue()
    game=cerebro.run()
    end_portfolio_value = cerebro.broker.getvalue()
    pnl = end_portfolio_value - start_portfolio_value
    print(f'Starting Portfolio Value: {start_portfolio_value:2f}')
    print(f'Final Portfolio Value: {end_portfolio_value:2f}')
    print(f'PnL: {pnl:.2f}')
    cerebro.plot(style="candlestick", volume=False)

exit()

the log :

posistion : 0
portvalue : 90000.0
cash : 90000.0     
dataval : 0.0      
posistion : 0      
portvalue : 90000.0
cash : 90000.0     
dataval : 0.0      
posistion : 0      
portvalue : 90000.0
cash : 90000.0     
dataval : 0.0      
posistion : 0      
portvalue : 90000.0
cash : 90000.0     
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
2018-01-02 BUY EXECUTED, 100.00
posistion : 473
portvalue : 90000.0
cash : 42700.0
dataval : 47300.0
posistion : 473
portvalue : 142030.0
cash : 42700.0
dataval : 99330.0
posistion : 473
portvalue : 146760.0
cash : 42700.0
dataval : 104060.0
posistion : 473
portvalue : 151490.0
cash : 42700.0
dataval : 108790.0
posistion : 473
portvalue : 156220.0
cash : 42700.0
dataval : 113520.0
posistion : 473
portvalue : 160950.0
cash : 42700.0
dataval : 118250.0
posistion : 473
portvalue : 165680.0
cash : 42700.0
dataval : 122980.0
posistion : 473
portvalue : 170410.0
cash : 42700.0
dataval : 127710.0
posistion : 473
portvalue : 175140.0
cash : 42700.0
dataval : 132440.0
2018-01-11 SELL EXECUTED, 190.00
posistion : -625
portvalue : 76320.0
cash : 251320.0
dataval : -175000.0
posistion : -625
portvalue : 82570.0
cash : 251320.0
dataval : -168750.0
posistion : -625
portvalue : 88820.0
cash : 251320.0
dataval : -162500.0
posistion : -625
portvalue : 95070.0
cash : 251320.0
dataval : -156250.0
posistion : -625
portvalue : 101320.0
cash : 251320.0
dataval : -150000.0
posistion : -625
portvalue : 107570.0
cash : 251320.0
dataval : -143750.0
posistion : -625
portvalue : 113820.0
cash : 251320.0
dataval : -137500.0
posistion : -625
portvalue : 120070.0
cash : 251320.0
dataval : -131250.0
posistion : -625
portvalue : 126320.0
cash : 251320.0
dataval : -125000.0
posistion : -625
portvalue : 132570.0
cash : 251320.0
dataval : -118750.0
posistion : -625
portvalue : 132570.0
cash : 251320.0
dataval : -118750.0
2018-01-02 BUY EXECUTED, 110.00
posistion : 697
portvalue : 245300.0
cash : 105900.0
dataval : 139400.0
posistion : 697
portvalue : 252270.0
cash : 105900.0
dataval : 146370.0
posistion : 697
portvalue : 259240.0
cash : 105900.0
dataval : 153340.0
posistion : 697
portvalue : 266210.0
cash : 105900.0
dataval : 160310.0
posistion : 697
portvalue : 273180.0
cash : 105900.0
dataval : 167280.0
posistion : 697
portvalue : 280150.0
cash : 105900.0
dataval : 174250.0
posistion : 697
portvalue : 287120.0
cash : 105900.0
dataval : 181220.0
posistion : 697
portvalue : 294090.0
cash : 105900.0
dataval : 188190.0
posistion : 697
portvalue : 301060.0
cash : 105900.0
dataval : 195160.0
2018-01-11 SELL EXECUTED, 190.00
posistion : -1075
portvalue : 141580.0
cash : 442580.0
dataval : -301000.0
posistion : -1075
portvalue : 152330.0
cash : 442580.0
dataval : -290250.0
posistion : -1075
portvalue : 163080.0
cash : 442580.0
dataval : -279500.0
posistion : -1075
portvalue : 173830.0
cash : 442580.0
dataval : -268750.0
posistion : -1075
portvalue : 184580.0
cash : 442580.0
dataval : -258000.0
posistion : -1075
portvalue : 195330.0
cash : 442580.0
dataval : -247250.0
posistion : -1075
portvalue : 206080.0
cash : 442580.0
dataval : -236500.0
posistion : -1075
portvalue : 216830.0
cash : 442580.0
dataval : -225750.0
posistion : -1075
portvalue : 227580.0
cash : 442580.0
dataval : -215000.0
posistion : -1075
portvalue : 238330.0
cash : 442580.0
dataval : -204250.0
Starting Portfolio Value: 90000.000000
Final Portfolio Value: 238330.000000
PnL: 148330.00

the test data (notice the dates are bogus and repeat themeselves):

1/2/2018,110,210,100,200
1/3/2018,120,220,110,210
1/4/2018,130,230,120,220
1/5/2018,140,240,130,230
1/6/2018,150,250,140,240
1/7/2018,160,260,150,250
1/8/2018,170,270,160,260
1/9/2018,180,280,170,270
1/10/2018,190,290,180,280
1/11/2018,190,290,180,280
1/12/2018,180,280,170,270
1/13/2018,170,270,160,260
1/14/2018,160,260,150,250
1/15/2018,150,250,140,240
1/16/2018,140,240,130,230
1/17/2018,130,230,120,220
1/18/2018,120,220,110,210
1/19/2018,110,210,100,200
1/20/2018,100,200,90,190
1/1/2018,100,200,90,190
1/2/2018,100,300,0,100
1/3/2018,120,220,110,210
1/4/2018,130,230,120,220
1/5/2018,140,240,130,230
1/6/2018,150,250,140,240
1/7/2018,160,260,150,250
1/8/2018,170,270,160,260
1/9/2018,180,280,170,270
1/10/2018,190,290,180,280
1/11/2018,190,290,180,280
1/12/2018,180,280,170,270
1/13/2018,170,270,160,260
1/14/2018,160,260,150,250
1/15/2018,150,250,140,240
1/16/2018,140,240,130,230
1/17/2018,130,230,120,220
1/18/2018,120,220,110,210
1/19/2018,110,210,100,200
1/20/2018,100,200,90,190
1/1/2018,100,200,90,190
1/2/2018,110,210,100,200
1/3/2018,120,220,110,210
1/4/2018,130,230,120,220
1/5/2018,140,240,130,230
1/6/2018,150,250,140,240
1/7/2018,160,260,150,250
1/8/2018,170,270,160,260
1/9/2018,180,280,170,270
1/10/2018,190,290,180,280
1/11/2018,190,290,180,280
1/12/2018,180,280,170,270
1/13/2018,170,270,160,260
1/14/2018,160,260,150,250
1/15/2018,150,250,140,240
1/16/2018,140,240,130,230
1/17/2018,130,230,120,220
1/18/2018,120,220,110,210
1/19/2018,110,210,100,200
1/20/2018,100,200,90,190

I understand nothing :
if we focus on the first buy order :

    # Check if we are in the market
        if not self.position:
            # We are not in the market, look for a signal to OPEN trades
            if self.datas[0].datetime.date()==datetime(2018,1,1).date() : 
                self.order = self.order_target_percent(target=1)  

the log :

posistion : 0
portvalue : 90000.0
cash : 90000.0
dataval : 0.0
2018-01-02 BUY EXECUTED, 100.00
posistion : 473
portvalue : 90000.0
cash : 42700.0
dataval : 47300.0

why is it buying only 473 SHARES and not using all my cash when I specified 1 in the target percent order ?

next the second order :

here, I am trying to reverse my position, obviously doing a bad job...

        # we are in the market
        elif self.datas[0].datetime.date()==datetime(2018,1,10).date() :
            self.order = self.order_target_percent(target=-1)  

posistion : 473
portvalue : 175140.0
cash : 42700.0
dataval : 132440.0
2018-01-11 SELL EXECUTED, 190.00
posistion : -625
portvalue : 76320.0
cash : 251320.0
dataval : -175000.0

What I understand is that before the sell, the size is 473, this is valued to 132440 which is approximately 0.75 * portvalue, so since I want my position to become -1, cerebro does something like -1/0.75*473 =630 to compute the new position. Once calculated it sells my 423 shares at the close price of the current bar ( since I did not use a limit order ?) which is 280 and not 190 as specified by order.executed.price ??? and it shorts approximately 630 SHARES, the best it can which gives a -625 size???
What is this 251320 cash value ?? why do I have so much cash after closing my position ? shouldn't i be 132440+42700 ?

As you understood, I am a newbie trader/ programmer, but I really tried reading the docs..

Please help me !!!