Charles_25

**The Problem:** I have a long string of serial numbers, that looks like this: "1_2_3_4_5 0_100_1_0_4 1_2_3_4_5 0_100_1_0_4 0_100_1_0_4 3_1_34_5_6"; I want to remove all serial numbers that do not occur EXACTLY 3 or 1 times in the string. **The Result:** In this case the return string should be: 0_100_1_0_4 …

My script merges 18 files and returns all numbers that occur >=13 times within the merger. I timed my script and array_count_values is so slow it accounts for 80% of the 2.35 sec time. The files are large, 200,000 numbers per file, so the merged array is well over 2 …