android:scaleY

added in API Level 11

scale of the view in the y direction.
A scaleY of 1 means no scaling is applied.

Ensure to change the minSDKVersion to 11, or greater.

       android:scaleY = ".5"

Related Articles:

Resources:
http://developer.android.com/reference/android/view/View.html#attr_android:scaleY
http://developer.android.com/reference/android/R.attr.html#scaleY