title: How to combine one letter and dot into a single row
body: <p>I have a dataframe with two columns. The columns is Word and Tag. The df looks as follows:</p>
  <pre><code>                     Word   Tag
  0                  bentuk    A
  1                   fisik    B 
  2              masyarakat    C 
  3                   serta    D  
  4              kebudayaan    E
  5                    yang    F
  6              dihasilkan    G
  7                       .    H
  8                       ;    I
  9                 William    O
  10                      A    O
  11                      .    B
  12                Haviland   X
  </code></pre>
  <p>and I'd like to merge some row contains one letter with dot <code>.</code> <code>letter+.</code> to one row. If there's a word meet dot, it won't merge. So the output should be the following:</p>
  <pre><code>0                  bentuk    A
  1                   fisik    B 
  2              masyarakat    C 
  3                   serta    D  
  4              kebudayaan    E
  5                    yang    F
  6              dihasilkan    G
  7                       .    H
  8                       ;    I
  9                 William    O
  10                     A.    O
  11                Haviland   X
  </code></pre>
  <p>Any ideas? Thanks in advance.</p>
  <p>Note: I have tried solution from @jezrael, but the output is</p>
  <pre><code>0                  bentuk    A
  1                   fisik    B 
  2              masyarakat    C 
  3                   serta    D
  4                      A.    O
  5              kebudayaan    E
  6                    yang    F
  7              dihasilkan    G
  8                       .    H
  9                       ;    I
  10                 William    O
  11                Haviland   X
  </code></pre>
  <p>the results are out of order</p>