0
if (document.getElementById("circular_select").checked === true) {
piechart();
}
if (document.getElementById("barras_select").checked === true) {
alert("You have selected Option 1");
}
<div class="btn-group custom-btn-group " data-toggle="buttons" >
<label class="btn btn-default active">
<img src="img/3d-pie-chart-icon.png" alt=""/>
<input type="radio" class="form-control" name="feature" value="opt0" id="circular_select" checked="checked" />
</label>
<label class="btn btn-default ">
<img src="img/SEO-icon.png" alt=""/>
<input type="radio" class="form-control" name="feature" value="opt1" id="barras_select" />
</label>
</div>