Read into csv file and make a graph out of it (Python)

Question

I write here because I am working on a Python project that logs the voltage values of a sensor connected to a Raspberry Pi through an ADC converter and write them in a csv file. This part is working just fine, however after the logging (which is triggered by a button in the GUIzero UI) is finished, I would like to be able to draw a graph of these values, triggered the same way.

This is why I would like to read all the data from the csv and store them into a table, which I can them define as the values from my y-axis, before I draw the graph with matplotlib. However, I couldn't find a proper way to do so, I tried to put these values into a table, but when I try to print it (just to check it is working well), nothing appears and my csv file is empty after that, which I don't want...

I am quite a newbie in programming/Raspberry Pi stuff so any help would be very appreciated ! Thanks in advance !

Rainman · Accepted Answer · 2023-07-26 15:08:27Z

1

Would pandas perhaps help? I'm not 100% sure what you're doing but you can save the contents of a csv file into a data frame like this:

import pandas as pd

df = pd.read_csv("file.csv",sep=',')

You can change the sep to whichever delimiter is separating your data. If your data has headers you can use:

df = pd.read_csv("file.csv",sep=',', header = 0)

answered Jul 26, 2023 at 15:08

Rainman

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3 Comments

Antoine Legrand Over a year ago

Thanks for your answer, I have found some sort of a solution; but it is still missing a little something to work perfectly. I managed to read all the values from the file and store them into a list, but for this I had to create the list first, with an interation of the number measured (1500, with the first value of the list equal to 1 and the last to 1500). Then in the loop reading the value, I replace the value of the table with the measurement. This is ok for me, however the values I read are into brackets and they are kind of not recognised by matplotlib when I ask him to draw the graph

Antoine Legrand Over a year ago

I get the following error : ValueError : setting an array element with a sequence. The requested array has an inhomogeneous shape after 1 dimensions. The detected shape was (1501, ) + inhomogeneous part

Rainman Over a year ago

Hey! Sorry, was out yesterday. Could you add a snippet of the csv file you're trying to import? Or a mock version if the contents are confidential.

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