Source code for spectran

"""
In this module functions for spectral analysis are collected 

"""

from scipy.fftpack import fft
import scipy.signal as spsig
import numpy as np

def stft(x, dt, window_type = 'hanning', window_len = 1200, step = 120, z_add = True):
	"""
	Calculating of STFT
	
	:param x: Samples
	:type x: numpy.ndarray
	
	:param dt: Sampling period
	:type dt: float
	
	:param length: Length of window in samples
	:type length: int
	
	:param window_type: Type of window
	:type window_type: str
	
	:param step: Step for STFT in samples
	:type step: int
	
	:returns: list
	
	"""
	window = spsig.get_window(window_type, window_len)
	X=[]
	for i in range(0, len(x)-window_len, step):
		if z_add:
			tmp = np.zeros(len(x))
			tmp[i:i + window_len] = x[i:i + window_len]*window
		else:
			tmp = x[i:i + window_len]*window
		X.append(abs(fft(tmp)))
		
	return X