TypeError: str object is not an iterator
<p>I have a file consisting of words, one word on each line. The file looks like this:</p>

<pre><code>aaa
bob
fff
err
ddd
fff
err
</code></pre>

<p>I want to count the frequency of the pair of words which occur one after the other.</p>

<p>For example,</p>

<pre><code>aaa,bob: 1
bob,fff:1
fff,err:2
</code></pre>

<p>and so on.
 I have tried this</p>

<pre><code>f=open(file,'r')
content=f.readlines()
f.close()
dic={}
it=iter(content)
for line in content:
    print line, next(line);
    dic.update({[line,next(line)]: 1})
</code></pre>

<p>I got the error: </p>

<pre><code>TypeError: str object is not an iterator
</code></pre>

<p>I then tried using an iterator:</p>

<pre><code>it=iter(content)
for x in it:
    print x, next(x);
</code></pre>

<p>Got the same error again. 
Please help!</p>

<pre><code>from collections import Counter
with open(file, 'r') as f:
    content = f.readlines()
result = Counter((a, b) for a, b in zip(content[0:-1], content[1:]))
</code></pre>

<p>That will be a dictionary whose keys are the line pairs (in order) and whose values are the number of times that pair occurred.</p>

python dictionary iterator generator