DataLogger | Android application for reliable multidevice multisensor

I am re-writing a program called Emissions Gateway to the new version of Ruby on Rails.

I have a method that was written with syntax from a gem called Squeel and I am having a very hard time re-writing it. I have been failing at it for over 4 hours and can't seem to get it figured out.

This is the method right here, it is in a model called datalogger.rb along with the schema information for the datalogger.rb model.

This is how my dataframe looks like:

I have datalogger that inserts a row with a timestamp every time the logger is turned on. The timestamp string is always the same format, but there are an inconsistent number of readings per timestamp.

How do I tidy the timestamp rows into a time variable?

This previous question is close, except I want the data in the extra rows to be a variable, not a header (it's also four years old, and I suspect there's a more elegant tidyverse solution these days): Tidy and Cast Data With Headers Stuck in Rows

I'm trying to read multiple sensors and saving all that data in one, singular, *.txt file. This is needed to enable it to analize and easily fill a database. But here is the catch, not all the sensors give int values, and as I learned the hard way, "String" gives to much unpredictable errors.

I want to read:

• Temperature
• Humidity
• Light intensity
• Sound

all saved as int
I also want to save

• 2 Accelero values (x,yand z values) as Float;
• a piece of text, just to log a status or debug as a String.

I tried to fill them into array but I'm overlooking something. Can someone please point me in the correct direction to make it work, that would help me alot!

For your interest, it should become a datalogger for a trailer for horses. So I get feedback about forces while driving and also the climate of the trailer and trigger camera and sound to monitor the animals (will be next step to livestream it and make it a IOT-system).

The code:

When trying to use Datalogger and Logbook I only get the latest reading when querying the device Logbook when I expect to get an array of the readings saved.

I'm trying to build a 1-Wire reading app to test the platform, I have defined a subscription API very similar to /Meas/Temp:

I'm trying to run the following google script then additionally input in column E (on the same row), 53- Column D (esentially =sum(53-D).

So the desired result in Google Sheets would be the following. The last number, 33 is what I'm trying to generate (53-20). So the 6th column (F) is the sum of 53-Column E.

1 2/5/2021 11:48:16 distance 20 33

I'm reading in multiple datalogger files, in .csv form, into Python. My objective is as follows:

• To read in each file from my directory, and if the filename starts with a K, then graph it in one color ... and if the filename starts with a Z, to graph those datapoints in another color.
• So, effectively, I want to have a plot with only two colors on it. One color from the files that started with "K", and another color from the files that started with "Z".

Where I'm stuck:

• In the code below, I'm only reading in the files from filenamesK. However, I would like to incorporate filenamesZ into this loop and plot them on the same graph.

• It's been a few years since I've programmed in Python (not in a technical role anymore), and I understand that there's probably a more efficient way to do what I'm doing :) .

  ...

I'm working on a C project for an embedded target running a Linux distribution (build with Yocto). I'm new to Linux embedded world and I have to build a data logging system.

I'm already learning how to use threads, and I'm thinking on the project organization.

Here is what I imagine :

• multiple threads to collect data from different interfaces, CAN bus, I2C... (different sample rate)
• one thread with a sample rate of 200ms to populate csv files
• one thread with a sample rate of 3 seconds to send data with http request
• Threads will stop on CAN info or external event

I don't know what is the best way to organize this project. I see two ways, in the first a startup program create each thread and wait in a while loop with event watching to stop them. The second way is a startup program execute others binaries as thread. In the two ways I don't know how share data between threads.

Can you share me your experience ?

Thank you

EDIT : First, thanks a lot to @Glärbo, for your explanations. It's really helpful to learn multi threading mechanic.

I've tested it with success.

For future readers I've drawn diagrams to illustrate @Glärbo answer.

main thread

productor-sensor thread

datalogger thread

I am trying to filter a dataset based on the date/time range (start and end time) and the id of each row from another dataset. The end result should be a list of filtered data frames.

Below is the code to create the two data sets.