CSVHandler.py

# -*- coding: utf-8 -*-
import csv
import io

class CSVFile(object) :
	"""
	A conveniant object that represents a CSV file.
	"""
	
	def __init__(self, path=None) :
		self._headers = list()
		self._data = dict()
		
		if path :
			self._load_file(path)
		else :
			#TODO : raise an exception
			print("No path provided for the creation of the CSVFile object.")
			
	@property
	def headers(self):
		return self._headers
		
	@property
	def data(self):
		return self._data
		
		
	def _load_file(self, path, template=None) :
		"""
		Loads the file pointed by `path` and populates the related properties. By default the function
		considers the file to be a set of the form
		
				header1		header2		header3		...		headerN
				val11		val12		val13				val1N
				val21		val22		val23				val2N
				...			...			...					...
				valM1		valM2		valM3				valMN
				
		where headerX are str objects and valYX are float objects.
		But one can provide a custom template if this does not meet your requirements.
		"""
		#TODO : implements the template feature.
		# Hint : `template` could be a dictionary where keys are field names and values are values types.
		# e.g. : template = {PRIM_X_CURRENT:float, ROOM_TYPE:str}
		with open(path, 'rb') as my_file:
			reader = csv.DictReader(my_file, dialect='excel', delimiter=',')

			# Process the whole file and populate self._data
			for line in reader :
				for (k,v) in line.items():
					if k not in self._data:
						self._data[k] = [v]
					else:
						self._data[k].append(float(v))	# The float conversion is needed because the DictReader returns str values by default.
					
			self._headers = reader.fieldnames
					
					
	def to_file(self, path) :
		"""
		Generate a csv file based on the CSVFile object.
		"""
		pass
		
	def __str__(self):
		if len(self._headers) > 3 or len(self._data[self._headers[0]]) > 15 :
			return "CSVFile object."
		else :
			result = ""
			for h in self._headers :
				result += h + " : " + str(self._data[h])
			return result
		
		

class Field(CSVFile):
	"""
	A CSVFile object that represents a single field (column).
	"""
	def __init__(self, header=None, values=None) :
		self._headers = [header]
		self._title = header
		self._data = dict()
		self._data[header] = values
		
	@property
	def title(self):
		return self._title
		
		
		
#========== TESTING ========== #
if __name__ == "__main__":
	import sys
	import os
	if os.path.isfile(sys.argv[1]):
		test_field = 8
		c = CSVFile(sys.argv[1])
		f = Field(header=c.headers[test_field], values=c.data[c.headers[test_field]])
		print(c)
		print(f)
	else:
		print("Error, the file does not exist")