Page Comparison

Adapted and simplified from Franck Albinet's exercises available here. Also presented by NSRC at APRICOT 2018.

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Let's explore and navigate this folder structure interactively. Connect to a Lopy via the Atom console . If there is a program running, use Control-C to stop it. and upload the source code for this exercise.

Import the basic operating system module (os): import os.Once imported: to know you current working directory:

import os
# to find you current working directory:
os.getcwd()

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 ## most probably the

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 /flashfolder
# to list folders and files in your current working directory:
os.listdir()

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# to create a new folder/directory named "log":
os.mkdir('log'); ...

Take a look at os module documentation for a full list of methods.

Now notice that if you list the files and folders under the root folder: os.listdir('/'),you get only the flash directory. There is no SD card mounted yet.

Writing

In the simplest case, to create and write a new file:

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Once open, you get a file object to play with and hence can start writing data in it:python  

f.write('Testing write operations in a file.')

Then you need to close the file to free up any system resources taken up by the open file. After calling f.close(), attempts to use the file object will automatically fail.

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For instance to read the file just created, you can use the following syntax:

with open('log/my_first_file.log', 'r') as f:
    f.readall()

This is much cleaner and safer.

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outputs a tuple (1970, 1, 1, 0, 21, 40, 3, 1) representing year, month, ...

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# formatting integer to string with list comprehension
['{:02d}'.format(i) for i in time.localtime()

outputs ['1970', '01', '01', '00', '24', '05', '03', '01']

# We keep only year, month, day, hour, min., sec. by slicing the list:

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['{:02d}'.format(i) for i in time.localtime()][:6]

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# last we join the list to a single string
''.join(['{:02d}'.format(i) for i in time.localtime()][:6])

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