Sum numbers by letter in list of tuples
<p>I have a list of tuples: </p>

<pre><code>[ ('A',100), ('B',50), ('A',50), ('B',20), ('C',10) ]
</code></pre>

<p>I am trying to sum up all numbers that have the same letter. I.e. I want to output </p>

<pre><code>[('A', 150), ('B', 70), ('C',10)] 
</code></pre>

<p>I have tried using set to get the unique values but then when I try and compare the first elements to the set I get </p>

<pre><code>TypeError: unsupported operand type(s) for +: 'int' and 'str'
</code></pre>

<p>Any quick solutions to match the numbers by letter?</p>

<p>A simpler approach</p>

<pre><code>x = [('A',100),('B',50),('A',50),('B',20),('C',10)]
y = {}
for _tuple in x:
    if _tuple[0] in y:
        y[_tuple[0]] += _tuple[1]
    else:
        y[_tuple[0]] = _tuple[1]
print [(k,v) for k,v in y.iteritems()]
</code></pre>

python list tuples