[R] reshape a data frame

[P. Stencel]

Dear R-helpers, 

I am trying to reshape a data frame which consists of only one column and of
several thousand rows. My purpose is to select every second element (row) of
the data frame and to create a second column with these elements. 

The data frame looks like this: 

COL1
23.190779669
74.659456135
74.019522268
27.099553199
50.02049443
76.518205961
75.924447203
75.774890661
...

Could anybody give me a piece of advice how to proceed? Are there any
commands to solve this problem?