Python 如何确定单词的概率?
我有两份文件。Doc1的格式如下:Python 如何确定单词的概率?,python,linux,probability,Python,Linux,Probability,我有两份文件。Doc1的格式如下: TOPIC: 0 5892.0 site 0.0371690427699 Internet 0.0261371350984 online 0.0229124236253 web 0.0218940936864 say 0.0159538357094 TOPIC: 1 12366.0 web 0.150331554262 site 0.0517548115801 say 0.0451237263464 Internet 0.0153647096879 on
TOPIC: 0 5892.0
site 0.0371690427699
Internet 0.0261371350984
online 0.0229124236253
web 0.0218940936864
say 0.0159538357094
TOPIC: 1 12366.0
web 0.150331554262
site 0.0517548115801
say 0.0451237263464
Internet 0.0153647096879
online 0.0135856380398
…以此类推,直到主题99,模式相同
Doc2的格式如下:
0 0.566667 0 0.0333333 0 0 0 0.133333 ..........
等等。。。每个主题的每个值总共有100个值
现在,我必须找到每个单词的加权平均概率,即:
P(w) = alpha.P(w1)+ alpha.P(w2)+...... +alpha.P(wn)
where alpha = value in the nth position corresponding to the nth topic.
也就是说,对于“说”这个词,概率应该是
P(say) = 0*0.0159 + 0.5666*0.045+.......
同样地,对于每个单词,我必须计算概率
For multiplication, if the word is taken from topic 0, then the 0th value from the doc2 must be considered and so on.
我只使用下面的代码计算单词的出现次数,但从未取过它们的值。所以,我很困惑
with open(doc2, "r") as f:
with open(doc3, "w") as f1:
words = " ".join(line.strip() for line in f)
d = defaultdict(int)
for word in words.split():
d[word] += 1
for key, value in d.iteritems() :
f1.write(key+ ' ' + str(value) + ' ')
print '\n'
我的输出应该如下所示:
say = "prob of this word calculated by above formula"
site = "
internet = "
等等
我做错了什么?假设您忽略了主题行,请使用defaultdict对值进行分组,然后在最后进行计算:
from collections import defaultdict
from itertools import groupby, imap
d = defaultdict(list)
with open("doc1") as f,open("doc2") as f2:
values = map(float, f2.read().split())
for line in f:
if line.strip() and not line.startswith("TOPIC"):
name, val = line.split()
d[name].append(float(val))
for k,v in d.items():
print("Prob for {} is {}".format(k ,sum(i*j for i, j in zip(v,values)) ))
另一种方法是边走边计算,每次点击一个新的部分,即一行主题,增加一个计数,通过索引从值中获取正确的值:
from collections import defaultdict
d = defaultdict(float)
from itertools import imap
with open("doc1") as f,open("doc2") as f2:
# create list of all floats from doc2
values = imap(float, f2.read().split())
for line in f:
# if we have a new TOPIC increase the ind to get corresponding ndex from values
if line.startswith("TOPIC"):
ind = next(values)
continue
# ignore empty lines
if line.strip():
# get word and float and multiply the val by corresponding values value
name, val = line.split()
d[name] += float(val) * values[ind]
for k,v in d.items():
print("Prob for {} is {}".format(k ,v) )
在doc2中使用两个doc1内容和0 0.566667 0 0.0333333 0
输出以下内容:
Prob for web is 0.085187930859
Prob for say is 0.0255701266375
Prob for online is 0.0076985327511
Prob for site is 0.0293277438137
Prob for Internet is 0.00870667394471
您还可以使用itertools groupby:
from collections import defaultdict
d = defaultdict(float)
from itertools import groupby, imap
with open("doc1") as f,open("doc2") as f2:
values = imap(float, f2.read().split())
# lambda x: not(x.strip()) will split into groups on the empty lines
for ind, (k, v) in enumerate(groupby(f, key=lambda x: not(x.strip()))):
if not k:
topic = next(v)
# get matching float from values
f = next(values)
# iterate over the group
for s in v:
name, val = s.split()
d[name] += (float(val) * f)
for k,v in d.iteritems():
print("Prob for {} is {}".format(k,v))
对于python3,所有的
imap
都应该更改为justmap
,这也会在python3中返回一个迭代器。所以比如说
0.0159538357094乘以5892.0?我只看到你在问题中乘以doc2文件中相应的元素不用担心,不客气。你让我有点困惑:)没问题,至少你自己做了很好的努力来解决它,这比这里很多人做的都多;)我将在a.m.中查看一下,但基本上我们只需要将.read().split()替换为拆分每一行,然后对每一行进行迭代,为每一行打开一个文件并编写输出。您是否完全按照发布的方式使用代码并使用python2?