how to create 2d array with 3 elements from 1d array using python

signals=([1998  ,1968  ,1937  ,1827  ,2027,2286  ,2484  ,2266  ,2107  ,1690,1808  ,1927  ,1924  ,1959  ,1889,1819  ,1824  ,1979  ,1919  ,1845,1801  ,1799  ,1952  ,1956  ,1969,2044  ,2100  ,2103  ,2110  ,2375,
    2030  ,1744  ,1699  ,1591  ,1770,1950  ,2149  ,2200  ,2294  ,2146,2241  ,2369  ,2251  ,2126  ,2000,1759  ,1947  ,2135  ,2319  ,2352,2476  ,2296  ,2400  ,3126  ,2304,
    2190  ,2121  ,2032  ,2161  ,2289,2137  ,2130  ,2154  ,1831  ,1899,2117  ,2266  ,2176  ,2089  ,1817,2162  ,2267])

Vectors=[[signals[i-1],signals[i+1],signals[i+3]] for i in range(1,len(signals-4))]
print Vectors

TypeError                                 Traceback (most recent call last)
<ipython-input-2-6f5b7430197d> in <module>()
     16     2190  ,2121  ,2032  ,2161  ,2289,2137  ,2130  ,2154  ,1831  ,1899,2117  ,2266  ,2176  ,2089  ,1817,2162  ,2267])
     17 
---> 18 Vectors=[[signals[i-1],signals[i+1],signals[i+3]] for i in range(1,len(signals-4))]
     19 print Vectors
     20 

TypeError: unsupported operand type(s) for -: 'list' and 'int'


Expected Output:[[signals[0],signals[2], signals[4]],[signals[1],signals[3],signals[5]],[signals[2],signals[4],signals[6]]]