How do i ignore rows with unique string while parsing a csv file in ruby

i开发者_如何学C want to ignore ALL

TopLevel, Result,,,,,,,,
AddHost,10.1.3.1,,,,,,,,

and

Flush,,,,,,,,,
AddHost,10.1.3.4,,,,,,,,

from

TopLevel, Result,,,,,,,,
AddHost,10.1.3.1,,,,,,,,
Add,10.1.3.1,43172
Add,10.1.3.1,44172
Add,10.1.3.1,4172
Add,10.1.3.1,432
Add,10.1.3.1,435472
Flush,,,,,,,,,
AddHost,10.1.3.4,,,,,,,,

---

Given the contents of the CSV file:

s = "TopLevel, Result,,,,,,,,
AddHost,10.1.3.1,,,,,,,,
Add,10.1.3.1,43172
Add,10.1.3.1,44172
Add,10.1.3.1,4172
Add,10.1.3.1,432
Add,10.1.3.1,435472
Flush,,,,,,,,,
AddHost,10.1.3.4,,,,,,,,
"

gsub will remove the offending lines:

s = s.gsub(/TopLevel, Result,,,,,,,,\nAddHost,10.1.3.1,,,,,,,,\n/, '')
s = s.gsub(/Flush,,,,,,,,,\nAddHost,10.1.3.4,,,,,,,,\n/, '')
puts s
# => Add,10.1.3.1,43172
# => Add,10.1.3.1,44172
# => Add,10.1.3.1,4172
# => Add,10.1.3.1,432
# => Add,10.1.3.1,435472

You may want regular expressions less specific than that. For example, if you want to remove ANY AddHost line following a TopLevel line, then the first regexp would be:

/TopLevel, Result,,,,,,,,\nAddHost.*\n/

When gsub is done munching on the file, pass the results to the CSV parser as normal.