MATLAB对于文本文件(txt)数据读取的技巧总结

可以将

IMPORTDATA

用于函数或者脚本 中，

因为在函数或者脚本中基于

GUI

的文件导入机制并不理想。

下面的例子用到包含几行文件头

和文 本、数值数据的文件

'sample_'

：

4

/

19

This is a file header.

This is file is an example.

col1 col2 col3 col4

A 1 4 612.000

B 1 4 613.000

C 1 4 614.000

D 1 4 615.000

Example: Using IMPORTDATA to read in a file with headers, text, and numeric data

CODE:

% This reads in the file 'sample_' and creates a

% structure D that contains both data and text data.

% Note the IMPORTDATA command specifies a white space

% as the delimiter of the file, but IMPORTDATA can usually

% detect this on its own

D = importdata('sample_','') %

原文有误？

D = importdata('sample_')

可以通过访问结构

D

的数据和文本域，来看 结构

D

中的真实值，例如输入：

data =

text = ta

UIIMPORT

读同一个文件并得到同样 的结构

.

5

/

19

注意

:

对于

ASCII data,

你必须检验导入向导正确的识别了列分隔符。

TEXTREAD/STRREAD

TEXTREAD

是一个强大的动态

high level routine

，

设计用来读

ASCII

< br>格式的文本和

/

或数值数据

文件 。

STRREAD

除是从字符串而不是文件读以外，类似于

TEXTREAD

。

两个函数可以用许多参数来改变其具体的工作方式，

他们返回读入指定输出的数据。

他们有

效的提供 给你一个

“

两全其美

”

的方法，因为他们可以用一个命令读入混合的

ASC II

和数值数据（

high

level

routines

的做法 ）

，

并且你可以改变他们以匹配你特定的应用

< br>（如同

low level routines

做到的）

。

例子：

CODE:

Example 1: Using TEXTREAD to read in an entire file into a cell array

% This command reads in the file fft.m into the cell array, file

file = textread ('fft.m','%s','delimiter','n','whitespace','');

CODE:

Example 2: Using STRREAD to read the words in a line

% This command uses the cell array created in Example 1 to

% read in each word of line 28 in 'file' to a cell array, words

words = strread(file{28},'%s','delimiter','')

CODE:

6

/

19

Example 3: Using TEXTREAD to read in text and numeric data from a file with headers

% This command skips the 2 header lines at the top of the file

% and reads in each column to the 4 specified outputs

[c1 c2 c3 c4] = textread('sample_','%s %s %s %s','headerlines',2)

CODE:

Example 4: Using TEXTREAD to read in specific rows of text and numeric data from a file

% This command reads in rows B and C of the file. The 'headerlines'

% property is used to move down to the desired starting row and the

% read operation is performed 2 times

[c1 c2 c3 c4] = textread('sample_',...

'%s %s %s %s',2,'headerlines',4)

CODE:

Example

5:

Using

TEXTREAD

to

read

in

only

the

numeric

data

from

a

file

containing

text

and

numbers

% This command reads in only the numeric data in the file. The

% 'headerlines' property is used to move down to the first row

% of interest and the first column of text is ignored with the

% '*' operator

[c2 c3 c4] = textread('sample_','%*s %d %d %f','headerlines',3)

DLMREAD/DLMWRITE/CSVREAD

7

/

19

DLMREAD

和

DLMWRITE

函数能够读写分隔的

ASCII data

，而不是用

low level routines

。他们

比

low

level

routines

容

易

使

用

，

Low

level

routines

用

几

行

代

实

现

的

功

能

可

以

用

DLMREAD/DLMWRITE

简化成一行。

CSVREAD

用来读分隔符是逗号的文件，是

DLMREAD

的特殊情况。当 读空格和

Tab

分隔的电

子数据表文件 时，

DLMREAD

特别有用。以

's ample_'

为例：

CODE:

Example 1: Using DLMREAD to read in a file with headers, text, and numeric data

% This reads in the file 'sample_' and creates a matrix, D,

% with the numeric data this command specifies a white space as the

% delimiter of the file

D = dlmread('sample_','')

CODE:

Example 2: Using DLMREAD to extract the first 3 columns of the last 3 rows

% This reads in the first 3 columns of the last 3 rows of

% the data file 'sample_'into the matrix, D_partial.

%

读文件

'sample_'

前

3

列后

3