阅读一个txt文件fscanf vs. fread与textscan

问题描述

我有一个从SQL-2005（ANSI格式）生成的.txt文件。我试过 textscan 和 fscanf 。整个txt文件只有数字数据。

在线资源表明fscanf比textscan更快，但是我发现它除此以外。

• 文本扫描比fscanf快得多
  
  
  

  我想用 fread 来试试这个，但我不知道如何使用fread导入数据。你能提出建议/评论吗？
  
  

    fName ='Test.txt'％从ANSI格式的SQL，5百万行，5列
   Numofrows = 1000000; ％1百万
   Numcols = 5; 
   
   fid = fopen（fName，'r'）; 
   C = textscan（fid，'％f％f％f％f％f'，Numofrows）; 
   C = cell2mat（C）; 
   
   fclose（fid）; fid = fopen（fName，'r'）; 
   [C，Count] = fscanf（fid，'％f％f％f％f％f'，Numofrows * Numcols）; 
   C =重塑（C，Count./Numofrows，Numofrows）; C = C; 
    

  
  

  解决方案

  还有另外一个选项， code> load

    L = load（fName）; 
    

  这很简单，并且会自动为您计算出格式。它有一些限制 - 格式应该有相同数量的每行。

  
  

  I have a .txt file that has been generated from SQL-2005 (in ANSI format). I have tried textscan and fscanf. The entire txt file has only numeric data.

  Online resources suggest that fscanf is FASTER than textscan but I found it otherwise.

  • Textscan was much faster than fscanf

  I want to try this with fread as well but I do not know how to import data using fread. Can you please suggest/comment? Thanks.

  fName     = 'Test.txt'    % From SQL in ANSI format, 5million rows, 5 Cols
  Numofrows = 1000000 ; %1million
  Numcols   = 5 ;
  
  fid = fopen(fName, 'r');
  C   = textscan(fid, '%f %f %f %f %f', Numofrows ) ;
  C   = cell2mat(C);
  
  fclose(fid); fid = fopen(fName, 'r');
  [C, Count] = fscanf(fid, '%f %f %f %f %f', Numofrows * Numcols ) ;
  C = reshape(C, Count./Numofrows , Numofrows ) ; C=C';
  

  解决方案

  There is another option that you did not list: load

     L = load(fName);
  

  It is very simple, and will figure out the format automatically for you. It does have some limitations - The format should have same amount of numbers in each line.

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