I'm new to Python as of 1 week ago and I'm trying to write a simple stock market backtester. In my program, I want to change a global variable called 'prev_entry_price' within a function I've defined and saved in a .py file within my project. But the variable doesn't change outside the function, and I don't understand why.
# -----------------
# Here is my code:
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# My input looks like this:
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# My output looks like this:
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The third column on the third row should contain '46.939999' but instead, it always comes back as '0'. When I use the debugger, it shows the modified value within the function, as expected. It even shows the modified value in both my calling argument, and called parameter. But still, I get '0' when I print. I've read and tried everything I could find on the Internet about how to use global variables to do this, and I can't get it to work. One other thing, the parameter on my function is grayed out, and when I hover my cursor over it, I see "Parameter 'prev_entry_price' value is not used." Does this matter?
Any help I receive would be greatly appreciated.
# -----------------
# Here is my code:
# -----------------
prev_entry_price = 0
prev_exit_price = 0
for row in range(2, 5):
# for row in range(2, sheet.max_row + 1):
sym_date_cell = sheet.cell(row, 1)
sym_open_cell = sheet.cell(row, 2)
sym_high_cell = sheet.cell(row, 3)
sym_low_cell = sheet.cell(row, 4)
sym_close_cell = sheet.cell(row, 5)
sym_volume_cell = sheet.cell(row, 7)
entry_price_cell = sheet.cell(row, 12)
exit_price_cell = sheet.cell(row, 13)
setup_eoddata(row, sym_open_cell, entry_price_cell, prev_entry_price, exit_price_cell, prev_exit_price)
print(f"Row ", row, prev_entry_price, entry_price_cell.value, exit_price_cell.value)
def setup_eoddata(row, sym_open_cell, entry_price_cell, exit_price_cell, prev_exit_price):
if row == 2:
global prev_entry_price
entry_price = sym_open_cell.value
entry_price_cell.value = entry_price
prev_entry_price = entry_price
exit_price = 0
exit_price_cell.value = exit_price
prev_exit_price = exit_price
return prev_entry_price, prev_exit_price# --------------------------# My input looks like this:
# --------------------------
1/2/2019 46.94 47.22 46.56 46.93 45.83 11,603,700 1/3/2019 46.82 47.37 46.53 46.64 45.55 14,714,400 1/4/2019 46.75 47.57 46.64 47.57 46.45 13,013,700 1/7/2019 47.57 47.75 46.90 46.95 45.85 13,135,500# --------------------------
# My output looks like this:
# --------------------------
Output:Row 2 0 46.939999 0
Row 3 0 None None
Row 4 0 None NoneThe third column on the third row should contain '46.939999' but instead, it always comes back as '0'. When I use the debugger, it shows the modified value within the function, as expected. It even shows the modified value in both my calling argument, and called parameter. But still, I get '0' when I print. I've read and tried everything I could find on the Internet about how to use global variables to do this, and I can't get it to work. One other thing, the parameter on my function is grayed out, and when I hover my cursor over it, I see "Parameter 'prev_entry_price' value is not used." Does this matter?
Any help I receive would be greatly appreciated.