Returns a DataFrame with the required format for 
	a scatter plot

	Parameters:
	-----------
		n_categories : int
			Number of categories 
		n : int
			Number of points for each category
		prefix : string
			Name for each category
		mode : string
			Format for each item
				'abc' for alphabet columns
				'stocks' for random stock names

def scatter(n_categories=5,n=10,prefix='category',mode=None):
	"""
	Returns a DataFrame with the required format for 
	a scatter plot

	Parameters:
	-----------
		n_categories : int
			Number of categories 
		n : int
			Number of points for each category
		prefix : string
			Name for each category
		mode : string
			Format for each item
				'abc' for alphabet columns
				'stocks' for random stock names
	"""	
	categories=[]
	for i in range(n_categories):
		categories.extend([prefix+str(i+1)]*n)
	return pd.DataFrame({'x':np.random.randn(n*n_categories),
						 'y':np.random.randn(n*n_categories),
						 'text':getName(n*n_categories,mode=mode),
						 'categories':categories})