Create a summary table from my data.frame : <p>I have the following data.frame, these are terror events happened in countries and the there can be 200 rows just for one country:</p>

<pre><code>Classes ‘data.table’ and 'data.frame':  80999 obs. of  3 variables:
 $ country_txt.factor: Factor w/ 166 levels "Afghanistan",..: 102 102 65 79 131 65 79 150 135 135 ...
 $ nkill             : num  0 0 1 0 6 0 0 0 0 0 ...
 $ nwound            : num  7 7 2 1 10 0 0 0 1 0 ...
</code></pre>

<p>I would like to create a new data.frame/table where i could make a summary like this:</p>

<pre><code>Country    Number of kills(sum)   Number of wounds (sum)
Iraq       14000                  150000
Afghanistan 10000                 8888
.
.
.
</code></pre>

<p>Can you help me please how could i do this? </p>
