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POeffeciently read large spreadsheet file in C++
 

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  1. POeffeciently read large spreadsheet file in C++
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    <p>I normally use the method described in <a href="https://stackoverflow.com/questions/1120140/csv-parser-in-c/1120224#1120224">csv parser</a> to read spreadsheet files. However, when reading a 64MB file which has around 40 columns and 250K rows of data, it takes about 4 minutes. In the original method, a CSVRow class is used to read the file row by row, and a private vector is used to store all the data in a row. </p> <p>Several things to note:</p> <ul> <li>I did reserve enough capacity of the vector but not much helpful.</li> <li>I also need to create instances of some class when reading each line, but even when the code just read in the data without creating any instances, it takes long time.</li> <li>The file is tab-delimited instead of comma-delimited, but I don't think it matters.</li> </ul> <p>Since some columns in that file are not useful data, I changed the method to have a private string member to store all the data and then find the position of the (n-1)th and the nth delimiter to get the useful data (of course there are many useful columns). By doing so, I avoid some push_back operations, and cut the time to a little more than 2 minutes. However, that still seems too long to me.</p> <p>Here are my questions:</p> <ol> <li><p>Is there a way to read such a spreadsheet file more efficiently?</p></li> <li><p>Shall I read the file by buffer instead of line by line? If so, how to read by buffer and use the csvrow class?</p></li> <li>I haven't tried boost tokenizer, is that more efficient?</li> </ol> <p>Thank you for your help!</p>
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