Creating a matrix subset in R -

i have big single row matrix (n=20000):

v1  col1 col2 col3 ... coln abc 1    3    5        2 

i want subset keep columns value >= 3:

v1  col2 col3 abc 3    5   

i have searched everywhere cannot come proper solution. suppose can transpose it, subset , transpose back?
appreciated.

logical indexing works on either i or j arguments "["

mtx[ , mtx > 3] # ............... 

read , study ?[ carefully. there power in function takes 10 readings gather of capacities , subtleties. (this may eve work on dataframe of appropriate construction , workings of "[" quite similar 2 structure=types.