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January 12, 2016 at 2:43 am #33758ParticipantPoints: 0Rank: Member
I'm trying to change headers of a very large csv file .
All headers have 'some_string' in each header name , like "some_string.header_name"
My csv file is big , more than 200G and has more than 200 columns
I'll very appricciate for any idea how to change headers fast and effectively !
January 12, 2016 at 2:51 am #33759ParticipantPoints: 60Rank: Member
Leaving aside why you're using a CSV file for a 200GB file for the moment, the use of StreamReader and StreamWriter is probably going to be your best bet.
Question I have though is do you have a fixed first line that you want to put in the CSV file, overwriting the first line, or do you actually want to do a search and replace of items in the first line?
If the latter, can you give more details?
January 12, 2016 at 4:38 am #33765ParticipantPoints: 0Rank: Member
I'd like to overwrite the csv first line . I thought about serach and replace strings in header . What solution is faster and effectively ? Overwriting or serach/replace of "somestring" ?
January 12, 2016 at 6:26 am #33777ParticipantPoints: 60Rank: Member
If you already know the text that is to go in the first line, i think it's a better method just to put it as the first line.
I don't have code to hand, but take a look at the StreamReader and StreamWriter. The method i'd imagine for use would be :
– Open output file with StreamWriter
– Write what the header is supposed to be
– Open input file
– Read the first line
– Loop through the rest of the file, performing a read operation of the input file followed by a write operation to the output file until you get to the end of the file.
-Close the streams
Because you read the first line of the input file, but do nothing, that means it will be ignored when you are creating the new output file.
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