Plot Cansat or any csv data using Python

Introduction

Many different methods exists. Here, we describe some. This use [[1]] data file. Download that and test the codes.

Theory of plotting log data

Method 1: CSV reader

Robust for errors in the csv file.

import csv
import matplotlib.pyplot as plt

#Create the array to store the datA
results = []

with open('satelliitti2021.txt') as csv_file:
    csv_read=csv.reader(csv_file, delimiter=" ")
    for row in csv_read:
        results.append(row)


#choose the data:
col = 6
data = []
for row in results:
    data.append( float( row[col] ) )

fig, ax = plt.subplots(figsize=(12,6))
print( data )
plt.plot( data )
plt.xlim([0,1600])
plt.ylim([-1, 5])
plt.show()

Method 2: Numpy

Does not care about the trailing spaces.

import matplotlib.pyplot as plt
import numpy as np

results = np.genfromtxt('satelliitti2021.txt', delimiter=' ')

fig, ax = plt.subplots(figsize=(12,6))
plt.plot( results[:,4] )
plt.xlim([0,1600])
plt.ylim([-1, 5])
plt.show()

Method 3: Pandas

Problems with trailing spaces.

import pandas as pd
import matplotlib.pyplot as plt

df = pd.read_csv('satelliitti2021.txt',
                   sep=" ",
                   header = None,
                   names=["v1", "v2", "v3", "ax", "ay", "az"])
#data.columns = ["time", "v1", "v2", "v3", "ax", "ay", "az"]
df.index.name="foo"
print( df )

print( df.columns )
print(df.v1)

ax = df.plot()
ax.set_ylim(-1,5)
plt.show()

Real time plotting

How to use Python to plot data acquired from the usb (COM) port. Will plot it real time, and save the data to be analyzed later.

Method 1 on Windows

import csv
import matplotlib.pyplot as plt

#Create the array to store the datA
results = []

with open(r'C:\Users\OPPILAS\Documents\Arduino\lampotilamittaus.txt', encoding="utf-8") as csv_file:
    csv_read=csv.reader(csv_file, delimiter=" ", quoting=csv.QUOTE_NONNUMERIC)
    for row in csv_read:
        results.append(row)
        #print( row )


#choose the data:
col = 2
data = []
for row in results:
    #print( row[col] )
    data.append( row[col] )

fig, ax = plt.subplots(figsize=(12,6))
print( data )
plt.plot( data )
plt.xlim([0,1600])
plt.ylim([-1, 5])
plt.show()

Method 1 with more columns to be printed

The colums before adding one more T and the time:

• 0, 8: Temperatures
• 16, 18, 20: Accelerometer in xyz directions

Change

#choose the data:
cols = [16, 18, 20]
data = []
for row in results:
    r = []
    for c in cols:
        r.append( row[c] )
 
    print( r )
    data.append( r )

References