Set Operator - how to extract only working day from all Friday of 2016.

When holiday2016 is the list of seq. number to represent national holidays and seq(1,365,7) is for all Friday in Friday
seq(1,365,7)[!is.element(seq(1,365,7),holiday2016)] will generate the list of sequence numbers for every working Friday in the year.

> holiday2016
 [1]   1   2  11  42  81 120 124 125 126 200 224 263 267 284 308 328 358
> seq(1,365,7)
 [1]   1   8  15  22  29  36  43  50  57  64  71  78  85  92  99 106 113 120 127 134 141 148 155 162 169 176 183 190 197
[30] 204 211 218 225 232 239 246 253 260 267 274 281 288 295 302 309 316 323 330 337 344 351 358 365
> seq(1,365,7)[!is.element(seq(1,365,7),holiday2016)]
 [1]   8  15  22  29  36  43  50  57  64  71  78  85  92  99 106 113 127 134 141 148 155 162 169 176 183 190 197 204 211
[30] 218 225 232 239 246 253 260 274 281 288 295 302 309 316 323 330 337 344 351 365