Initialize counter with result from previous run saved to a file

Question

I am using a program using python that counts pulses with the GPIO and stores them in a text file. How can I update that program in such a way that when the program is restarted or else update the rapsberry pi, the counter will continue to count from the last count that was before?

counter = 0

def my_callback2(channel)

global counter
counter = counter + 1
print counter

file = open("testfile.txt", "w")
file.write(str(counter))

file.close()
with open('testfile.txt', 'r') as f:
    first_line = f.readline()

print "switch press detected"

Asked By: Andrew Attard

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Answer 1

There must be easier ways but this will do it:

order_idFile = open('some_file.txt', 'r') # open file for reading
order_id = int(order_idFile.read().strip()) # read file contents, strip it and convert a str to int
order_idFile.close() # close file
order_id += 1 # add 1 to current number
order_idFile = open('some_file.txt', 'w') # open file for writing 
order_idFile.write(str(order_id)) # convert int to str and write to file
order_idFile.close() # close file

Note:
some_file.txt must have a valid number (0 perhaps?) the first time you run the script.

Answered By: Pedro Lobito

Initialize counter with result from previous run saved to a file

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