batch rename csv headers

PowerShell Help
1

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 !

2

Hi liri321

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?

3

Hi Tim

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” ?

Thanks !

4

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.