Python math.log函数代码示例

 def _get_value_log(self, x, mu, v):
     """log basic 2"""
     try:
         return loggamma(x+v) - loggamma(x+1) - loggamma(v) + v*log(v) - v*log(v+mu) + x*log(mu) - x*log(v+mu)
     except ValueError:
         #print('_get_value_log ValueError', x, mu, v, file=sys.stderr)
         return 1

def make_dictionary(file_array):

	cufflinks_dict={}

        for i in range(0,len(file_array)):
		if file_array[i] != '':
			prelim_info_list=[]
                	each_gene_list=file_array[i].split("\t")
						
			try:	
				##Prelimnary Info
				entry_name=each_gene_list[0]
				Gene_ID=each_gene_list[3]
				Gene_Name=each_gene_list[4]
				tss_id=each_gene_list[5]
				locus=each_gene_list[6]
				length=each_gene_list[7]
				coverage=each_gene_list[8]
				FPKM=each_gene_list[9]
				
				log2_FPKM=math.log(float(FPKM)+1)/math.log(2)
				
				if entry_name not in cufflinks_dict:
					cufflinks_dict[entry_name]=entry_name+"\t"+Gene_ID+"\t"+Gene_Name+"\t"+tss_id+"\t"+locus+"\t"+str("%.4f" % log2_FPKM)
				else:
					pass
			except:
				pass
	
	return cufflinks_dict

	def getFitness(self, tagList):

		tagList = list(tagList)

		# add start symbols and end symbols
		for i in range(self.N - 1):
			tagList.insert(0, '^')
			tagList.append('$')

		# initialize the variables
		answer = float(0.0)

		# calculate numerator & denominator
		length = len(tagList)
		# print "----- before calculation -----"
		for start in range(length - self.N + 1):
			tmp = []
			for index in range(self.N):
				tmp.append(tagList[start+index]) 
			gramTuple = tuple(tmp) # now gramTuple is the tuple for this NGRAM (self).

			gramTupleProb = self.getProb(gramTuple)
			answer += math.log(gramTupleProb)
			if start != 0:
				prefixGramTuple = self.getPrefixGram(gramTuple)
				prefixGramTupleProb = self.prefixNGRAM.getProb(prefixGramTuple)
				answer -= math.log(prefixGramTupleProb)
			# print "numerator = %f, denominator = %f, answer = %f" % (numerator, denominator, answer)
		# print "----- after calculation -----"
		# special casef

		return answer

def compute_disp_ntaps(dm,bw,freq):
	NTLIMIT=65536*2
	#
	# Dt calculations are in Mhz, rather than Hz
	#    crazy astronomers....
	mbw = bw/1.0e6
	mfreq = freq/1.0e6

	f_lower = mfreq-(mbw/2)
	f_upper = mfreq+(mbw/2)

	# Compute smear time
	Dt = dm/2.41e-4 * (1.0/(f_lower*f_lower)-1.0/(f_upper*f_upper))

	# ntaps is now bandwidth*smeartime
	ntaps = bw*Dt
	if (ntaps < 32):
		ntaps = 32
	# special "flag" from command-line invoker to get around a bug
	#   in Gnu Radio involving the FFT filter implementation
	#   we can *never* increase the size of an FFT filter at runtime
	#   but can decrease it.  So there's a special "startup" flag (dm=1500.0)
	#   that causes us to return the NTLIMIT number of taps
	#
	if (dm >= 1500.0):
		ntaps = NTLIMIT
	if (ntaps > NTLIMIT):
		ntaps = NTLIMIT
	ntaps = int(math.log(ntaps) / math.log(2))
	ntaps = int(math.pow(2,ntaps+1))
	return(int(ntaps))

def TF_IDF():
    print('Doing TF_IDF', file=sys.stderr)
    global TFIDF, docWeight, index

    if os.path.isfile('TFIDF.dat') and os.path.isfile('docWeight.dat') and os.path.isfile('index.dat'): 
        f = open('TFIDF.dat', 'rb')
        TFIDF = pickle.load(f)
        f.close()
        f = open('docWeight.dat', 'rb')
        docWeight = pickle.load(f)
        f.close()
        f = open('index.dat', 'rb')
        index = pickle.load(f)
        f.close()

    else:
        print('.dat not exist, generating', file=sys.stderr)

        TFIDF = {}
        docCnt = len(docSize)
        avgSize = 0
        index = [[] for i in range(docCnt)]
        for i in range(docCnt):
            avgSize += docSize[i]
        avgSize /= docCnt
        
        docWeight = [0 for i in range(docCnt)]
        para_b = 0.7 # tuning
        d = [(1 - para_b + para_b*docSize[i]/avgSize) for i in range(docCnt)]


        for i in invIndexUnigram: # word id
            IDF = math.log( docCnt / len(invIndexUnigram[i]) )
            TFIDF[i] = {}
            for j in invIndexUnigram[i]: # doc id
                v =  (invIndexUnigram[i][j] / d[j]) * IDF
                TFIDF[i][j] = v
                docWeight[j] += v * v
                index[j].append(i)

        for i in invIndexBigram: # word id
            IDF = math.log( docCnt / len(invIndexBigram[i]) )
            TFIDF[i] = {}
            for j in invIndexBigram[i]: # doc id
                v =  (invIndexBigram[i][j] / d[j]) * IDF
                TFIDF[i][j] = v
                docWeight[j] += v * v
                index[j].append(i)

        f = open('TFIDF.dat', 'wb')
        pickle.dump(TFIDF, f)
        f.close()
        f = open('docWeight.dat', 'wb')
        pickle.dump(docWeight, f)
        f.close()
        f = open('index.dat', 'wb')
        pickle.dump(index, f)
        f.close()

    printTime()

def could_be_prime(n):
	'''Performs some trials to compute whether n could be prime. Run time is O(N^3 / (log N)^2) for N bits.

Returns whether it is possible for n to be prime (True or False).
'''
	if n < 2:
		return False
	if n == 2:
		return True
	if not n & 1:
		return False

	product = ONE
	log_n = int(math.log(n)) + 1
	bound = int(math.log(n) / (LOG_2 * math.log(math.log(n))**2)) + 1
	if bound * log_n >= n:
		bound = 1
		log_n = int(sqrt(n))
	prime_bound = 0
	prime = 3

	for _ in xrange(bound):
		p = []
		prime_bound += log_n
		while prime <= prime_bound:
			p.append(prime)
			prime = next_prime(prime)
		if p != []:
			p = prod(p)
			product = (product * p) % n

	return gcd(n, product) == 1

def mdl (g):
    """
    the Minimum Descrition Length calculator for Bayesian network g
    """
    n = len (g.V) # the variable count
    N = len (g.data)# the sample number
    
    logn = math.log (n, 2) # value of log (n)
    logN = math.log (N, 2) # value of log (N)
    
    complexity = sum([logn * len(g.getParentOf(v)) + logN / 2 * product (g.getParentOf(v).cards()) * (v.card - 1) 
                      for v in g.V]) 
    
    logll = 0 #log likelihood 
    for v in g.V:
        for parentVals in g.getParentOf (v).allAssignments ():
            for val in v.values:
                # assignment of the parent
                parentAssignments = dict(zip(map(lambda p: p.var, g.getParentOf (v)), parentVals))
                
                assignments = parentAssignments.copy () #including the child value in the assignment
                assignments[v.var] = val
                
                #the empirical count of the given assignments of parent
                parentN = g.N (**parentAssignments)
                
                #the empirical count of the given assignments of parent and child
                childN = g.N (**assignments)

                if childN != 0:
                    logll += (childN * math.log (childN / parentN, 2))                
                else:
                    pass #nothing happens

    return -logll + complexity

    def __init__(self, ref_file, max_n=100, verbose=False):
        '''
        Read the reference file and store wordcounts as class variables:
        - a dictionary mapping words to their log probabilities
        - a dictionary mapping character patterns (e.g. 'abccda' for 'dotted')
          to a list of words and their log probabilities, sorted by probability
        '''
        self.max_n = max_n
        self.verbose = verbose
        if self.verbose:
            print 'processing reference file...'

        # Get words and word probabilities from text and put in dictionary
        self.vectorizer = CountVectorizer(token_pattern=r'(?u)\b[a-zA-Z]+\b')
        wordcounts = self.__get_wordcounts(ref_file)
        self.word_dict = {word:math.log(count+1.0) for count, word in wordcounts}

        # Also put words and probabilities into the dictionary keyed by pattern
        self.words_by_pattern = {}
        for count, word in wordcounts:
            pattern = self.__word_to_pattern(word)
            prob = math.log(count+1.0)
            if pattern in self.words_by_pattern:
                self.words_by_pattern[pattern].append((prob, word))
            else:
                self.words_by_pattern[pattern] = [(prob, word)]

        # Initial null solution
        self.solution = None
        if self.verbose:
            print '...done\n'

    def __next__(self):
        rv = self.value

        #------------------------------------------------------------------------
        # need to round or we might succumb to the dreaded python rounding
        # error (eg 0.99999 < 0 when multiplying 1/24.0 by 24)
        #------------------------------------------------------------------------
        if round(self.pos, 8) >= round(self.length_cur, 8):
            self.value = 1.0
            rv = 1.0
            self.pos = 0
            self.length_cur = Pattern.value(self.length)
            amp_cur = Pattern.value(self.amp)
            rate_start = 1.0
            rate_end = 1.0 + amp_cur
            steps = TICKS_PER_BEAT * self.length_cur
            self.dv = math.exp(math.log(rate_end / rate_start) / steps)

        self.pos += 1.0 / TICKS_PER_BEAT
        self.value = self.value * self.dv
        #------------------------------------------------------------------------
        # subtract 
        #------------------------------------------------------------------------
        rv = math.log(rv, 2)
        print("warp: %f" % rv)
        return rv

def make_non_differential_constellation(m, gray_coded):
    side = int(pow(m, 0.5))
    if (not isinstance(m, int) or m < 4 or not is_power_of_four(m)):
        raise ValueError("m must be a power of 4 integer.")
    # Each symbol holds k bits.
    k = int(log(m) / log(2.0))
    if gray_coded:
        # Number rows and columns using gray codes.
        gcs = gray_code(side)
        # Get inverse gray codes.
        i_gcs = mod_codes.invert_code(gcs)
    else:
        i_gcs = range(0, side)
    # The distance between points is found.
    step = 2.0/(side-1)

    gc_to_x = [-1 + i_gcs[gc]*step for gc in range(0, side)]
    # First k/2 bits determine x position.
    # Following k/2 bits determine y position.
    const_map = []
    for i in range(m):
        y = gc_to_x[get_bits(i, 0, k/2)]
        x = gc_to_x[get_bits(i, k/2, k/2)]
        const_map.append(complex(x,y))
    return const_map

def predict_class(prediction, prob_other, class_doc_stats, class_prob, word_list, word_dict):
    prob_values = []
    new_prob_values = []
    for class_name in class_prob:
        prob_values.append((class_name, class_prob[class_name]))
    inpfile = open("stopWords.txt", "r")
    line = inpfile.readline()
    stopWords = []
    while line:
        stopWord = line.strip()
        stopWords.append(stopWord)
        line = inpfile.readline()
    inpfile.close()
    for val in prob_values:
        prob = math.log(val[1], 2)
        class_name = val[0]
        for word in word_list:
            word = word.lower()
            # val = re.search(r"^[a-zA-Z][a-zA-Z0-9]*[a-zA-Z]+[a-zA-Z0-9]*$", word)
            # if (word in stopWords):
            #	continue
            if word in word_dict:
                prob = prob + math.log(Decimal(word_dict[word][class_name]), 2)
            else:
                prob = prob + math.log(Decimal(prob_other[class_name]), 2)
        new_prob_values.append((class_name, prob))
    prob_values = new_prob_values
    prob_values.sort(key=lambda tup: tup[1], reverse=True)
    return prob_values, prob_values[0][0]

def deviation_score(percentage, lower_bound, upper_bound):
    if percentage < lower_bound:
        return math.log(lower_bound - percentage, lower_bound) * 100
    elif percentage > upper_bound:
        return math.log(percentage - upper_bound, 100 - upper_bound) * 100
    else:
        return 0

 def relate(size, base):
     if size == 0:
         return base
     size = float(size)
     base = float(base)
     if abs(size - base) < 0.1:
         return 0
     sign = -1 if size < base else 1
     endp = 0 if size < base else 36
     diff = (abs(base - size) * 3) + ((36 - size) / 100)
     logb = abs(base - endp)
     if logb == 1.0:
         logb = 1.1
     try:
         result = sign * math.log(diff, logb)
     except ValueError:
         if diff < 0:
             # Size is both very large and close to base
             return 0
         if logb == 0:
             logb = 1e-6
         if diff == 0:
             diff = 1e-6
         result = sign * math.log(diff, logb)
     return result

def estimDiv(c, psmc, r, t):
    """Estimate divergence using eq 12
    """
    N0 = 0
    if psmc:
        if not r:
            # parse psmc
            f = open(psmc, 'r')
            line = f.readline().split("-eN ")
            t = [float(i.split()[0]) for i in line[1:]]
            t.insert(0, 0.0)
            r = [float(i.split()[1]) for i in line[1:]]
            N0 = float(line[0].split()[1]) / float(line[0].split()[4])
            r.insert(0, 1.0)
        i = 0
        nc = 1.0
        while (1-nc*exp(-(t[i+1]-t[i])/r[i])) < c:
            nc *= exp(-(t[i+1]-t[i])/r[i])
            i += 1
            #print("i:{}, t[i]:{}, t[i+1]:{}, r[i]:{}, nc:{}".format(i, t[i], t[i+1], r[i], nc))
        j = i
        print("nc = {}, 1-nc = {}".format(nc, 1-nc))
        T_hat = -r[j]*log((1-c) / nc) + t[j]
    else:
        T_hat = -log(1-c)  # assumes constant popsize
    return(r, t, N0, T_hat)

def command_line(veb, ra, ov, pr):
	l = len(sys.argv)
	for i in xrange(1, l):
		if not is_switch(sys.argv[i]):
			break

	for j in xrange(i, l): # Start with the first non-switch
		if j != i: # Pretty printing
			print
		response = sys.argv[j]
		if valid_input(response):
			response = response.replace('^', '**')
			try:
				n = eval(response)
				int(n)
			except (SyntaxError, TypeError, ValueError):
				help()
		else:
			help()

		print	'Factoring %d:' % n
		if n < 0:
			print	-1
			n = -n
		if n == 0:
			print	'0 does not have a well-defined factorization.'
			continue
		elif n == 1:
			print	1
			continue

		if ov == DUMMY:
			ov = 2*math.log(math.log(n))
		for factor in factors(n, veb, ra, ov, pr):
			print factor