Script that finds positive maxima values for data points representing a sine function.

sineMaxFinder.py

""" 

Script to find the maximum of each wave in a period for a given dataset

Cameron Carmichael Alonso, 2016

"""
import os

def calculateMaxPoints(file, fileName):

	# we'll want to fill these variables later
	lastAmplitude = 0.0
	total = 0
	greater = 0
	maximums = []

	fileContents = file.read().splitlines()

	# Iterate
	for lineX in range(0, len(fileContents)):

		# Only lines greater than 1 (i.e. avoid headers)
		# Lines less than total length of file - 1 (to avoid "next"-effect)
		if lineX > 1 and lineX < (len(fileContents) - 1):

			# Get line at index
			line = fileContents[lineX]

			# Split second tuple index
			content = line.rstrip().split(",")

			# Get values
			time = content[0]
			amplitude = content[1]

			# Increment total
			total += 1

			# Check if greater than last amplitude
			if amplitude > lastAmplitude:

				# Get next line
				lineNext = fileContents[lineX + 1]

				# Split second tuple index
				contentNext = lineNext.rstrip().split(",")

				# Get values
				amplitudeNext = contentNext[1]

				# Check that value is greater than next
				if amplitude > amplitudeNext:

					# Finally, check this is positive
					# We only want to analyse the y > 0 range

					print amplitude

					if float(amplitude) > 0:

						print amplitude

						# We have a maximum!
						greater += 1

						# Store in array
						maximums.append([time, amplitude])
			
			# Set last amplitude
			lastAmplitude = amplitude

	# print statistics
	print "Total data points is " + str(total)
	print "Total number of maximums is " + str(greater)

	# write to .max.csv
	strToWrite = ""
	for maxima in maximums:

		# Join into string
		value = ",".join(maxima)

		# Add newline
		value += "\n"

		# Append
		strToWrite += value	

	# Construct new file name
	newFileName = fileName.replace(".csv", ".max.csv")

	# Delete file if it already existws
	try:
		os.remove(newFileName)
	except OSError:
		pass

	# Write
	with open (newFileName, 'a') as f: f.write (strToWrite)

	# Show status
	print "Written to file " + newFileName

# Main entry point
if __name__ == "__main__":

	# Get name of file to read
	fileName = raw_input("Relative file path: ")

	# Try to open file
	try:

		with open(fileName, 'r') as file:

			# Run method
			calculateMaxPoints(file)

	except Exception, e:

		print str(e)