title: Find count of characters within the string in Python
body: <p>I am trying to create a dictionary of word and number of times it is repeating in string. Say suppose if string is like below</p>
  
  <pre><code>str1 = "aabbaba"
  </code></pre>
  
  <p>I want to create a dictionary like this </p>
  
  <pre><code>word_count = {'a':4,'b':3}
  </code></pre>
  
  <p>I am trying to use dictionary comprehension to do this.
  I did </p>
  
  <pre><code>dic = {x:dic[x]+1 if x in dic.keys() else x:1 for x in str}
  </code></pre>
  
  <p>This ends up giving an error saying</p>
  
  <pre><code>  File "&lt;stdin&gt;", line 1
      dic = {x:dic[x]+1 if x in dic.keys() else x:1 for x in str}
                                                 ^
  SyntaxError: invalid syntax
  </code></pre>
  
  <p>Can anybody tell me what's wrong with the syntax? Also,How can I create such a dictionary using dictionary comprehension?</p>