Micropython can it list to file, and backwards?

[Mr Jos]

Hey,

(I have never coded before with Python, but have been learning it last week with online reading a lot, this problem I can not find)

I changed my project from 3 bricks running EV3-G to 1 remaining on EV3-G, other 2 changed to Pybricks, micropython.

As far as moving the motors it works now perfect, better then 3x EV3-G. Bluetooth is now server(pybrick) with 2 clients(1pybrick, 1ev3-g), another big problem that got solved.

 

But: I used to make a WareHouse Managing File on 1 of the now server Pybrick. I tried to make a .txt file that is stored when the program does not run. Then it should everytime open the file and fill in a list 'online' to access and change the states.

The problem I run into is that when I try to save the 'online' list to the 'offline' .txt file, it puts all of the input on 1 line instead of each line 1 state (True or False).

Next run of the program it should load in the file, but as it's all in 1 line, there's only 1 element to put in the list, rest is blank.

 

On the first picture it's printed as I want it, every line of print has it's own True/False (later I will use the testlist[position] to see if a position already has a box or not). But I get the last picture after starting the program with an empty testlist.

 

TL,DR:

Anyone knows how I can put several "strings" each on 1 line in a .txt file with MicroPython, taking the inputs from a list.

 

Edited November 8, 2020 by Mr Jos
grammar

[Lok24]

Hi,

sounds like a nice project!

As far as I know the python "write" which you use does not add a "new line" (whereas your print does!)
Try file1.write("your value \n")

 

Edited November 8, 2020 by Lok24

[Mr Jos]

I tried it before, for some odd reason it adds a blank line in between the values.

I'll try to replicate again and show it.

Edit:

Here it is, as you can see it adds the first value correct on 1 line, but then adds and empty line, then 2nd value on 3rd line, empty, etc.

Edited November 8, 2020 by Mr Jos

[Lok24]

What happens if you add the \n only in line 93 ?

(and not in line 85, the print command)?

[Mr Jos]

I only added it in line 93 -->  + "\n"

line 85 remained the same in all 3 pictures, it just reads value per value from the list, that works good.

Somehow the .txt writing puts all on 1 line(second picture), or puts directly an empty line in between the values(third picture).

Actually it adds and extra empty line every time I run the program starting from an empty list. (1st time 1empty, 2nd time 3empty, 4th time loads of empty lines)

Edited November 8, 2020 by Mr Jos

[Lok24]

yes, because you have the \n in "write" and and automatic \n in "print"

Just found that to remove the \n while "read"

https://stackoverflow.com/questions/15233340/getting-rid-of-n-when-using-readlines

Or just read the complete file without loop.......

HTH

[Mr Jos]

Ah! Thank you, didn't know it automatically added a \n in print!

After reading in the link you gave me I managed to solve the problem, thank you! It works the same everytime I restart the program, will do some further testing as to how it works and i can make a WMS from it.

Full working High Bay Warehouse coming soon :D

[David Lechner]

Python tip 1:

The range function provides the next number in each iteration of the loop, so instead of

count = 0
for x in range(10):
    print(my_list[count])
    count += 1

You can write:

for x in range(10):
    print(my_list[x])

which leads to...

Python tip 2:

Lists are iterators, so instead of using

for x in range(10):
    print(my_list[x])
    

You can do this:

for item in my_list:
    print(item)

 

Python tip 3:

You can use the print function to print to a file

print("stuff", file=my_file)

This will automatically add the newline.

 

Putting this all together

with open("my-file", "w") as f:
    for item in list:
        print(item, file=f)

 

The title also mentioned backwards:

with open("my-file", "w") as f:
    for item in reversed(list):
        print(item, file=f)

 

[Mr Jos]

5 hours ago, David Lechner said:

Python tip 1: Thanks, already found this one out today

Python tip 2: Thanks, already found this one out today as well

Python tip 3: Thanks, something new learned again

You can use the print function to print to a file

print("stuff", file=my_file)

This will automatically add the newline.

 

Putting this all together

with open("my-file", "w") as f:
    for item in list:
        print(item, file=f)

 

The title also mentioned backwards:

with open("my-file", "w") as f:
    for item in reversed(list):
        print(item, file=f)

 

I cleaned it up today already after some testing and reading/learning.

The backwards in the title was actually just for list --> file [104:106] , backwards = file --> list [92:93]. But as you can see on the photo I already managed to get that.

Now the program is already running full initialising all 3 brick's motors/sensors, positions of boxes on conveyors are being found. Boxes in the high bay rack are stored offline in the file correctly. Choosing automatically a free spot in the rack is being done good. Next part to program tomorrow is automatically returning boxes if in 'auto' mode.

Then the hardest part is left, to make a HMI with the 2 Python bricks. Many more reading/learning wil be done this week.

Edited November 9, 2020 by Mr Jos
grammar

[David Lechner]

Looking good.

[Mr Jos]

2weeks of learning Python, from 0 to ...

It's not perfect the HMI, few bugs with information updating to late on screen. But overall works well. Next will be the HMI on second screen for 'online' parameter adjustment.

[Lok24]