在MATLAB中跳过阅读字符串 [英] Skip reading strings in MATLAB

问题描述

我使用 xlsread 在MATLAB中有简单的命令可以防止程序在读取字符时崩溃吗？ >读取一个（20 400）矩阵数据，第一行和第一列因为有标题而忽略
，所以：

  data = xlsread（'C：\file.xls'）
  

code> data ，大小为（19 399）。

我有一个问题，有些单元格缺少数据， 'missing'，在一些数据集上我有头文件重新出现在中间。

有没有一种方法可以跳过这些字符没有程序崩溃，我不得不打开文件excel和删除这些字段？

谢谢

---

后期更新。这里是我正在使用的代码：

$ p $ [a，patha] = uigetfile（{'*。csv'}，'Select文件'，'c：\Data\2010'）;
file1 = [patha a];

％＃得到一个文件ID
fid = fopen（file1，'rt'）;
newf = textscan（fid，['％s'repmat（'％f'，1,27）]，'HeaderLines'，1，'Delimiter'，'，'）;
fclose（fid）;

％//创建第一列的日期数据
time = datenum（newf {1}）;

％//找出每行的分钟数
timeDiff = round（diff（datenum（time）*（24 * 60）））;

％//其余数据
newf = cell2mat（newf（2:28））;


我得到的错误是：

  ???错误使用==> cat 
 CAT参数维度不一致。 
 
错误==> cell2mat at 81 
 m {n} = cat（2，c {n，：}）; 
 
错误==> testprogram at 31 
 pwr = cell2mat（newf（2:28））; 
  

这是由于我选择的文件中的字符。它会消失，当我手动删除它们

解决方案

如果字符串不符合期望，文本扫描失败。空白条目导致链接时出现问题 - 您的数组将有不平衡的列数。

  textscan（'bla，5.4，缺少3,3,3,4'，'％s％f％f％f％f％f'，'Delimiter'，'，'）
 
 ans = 
 
 {1x1 cell} [5.4000] [0x1 double] [0x1 double] [0x1 double] [0x1 double] 
  

<但是，您可以使用'TreatAsEmpty'，将'missing'视为空（即它们被NaNs取代）。

pre $ textscan（'bla，5.4，missing，3,3,3.4'，'％s％f％f％f％f％f'，'Delimiter'，'，'，'TreatAsEmpty'，'missing'）

ans =

{1x1 cell} [5.4000] [NaN] [3] [3] [3.4000]


这可以让你运行cell2mat而不会出现问题。

Is there is easy command in MATLAB which prevents program from crashing when it reads characters?

I use xlsread to read a (20 400) matrix data , the first row and column get disregarded as they have headers, so that:

data = xlsread ('C:\file.xls') 

results in data with a size of (19 399).

I have a problem, some cells have missing data and it's written 'missing' and on some data sets i have headers reappear in middle.

Is there a way to skip these characters without the program crashing and me having to open the file in excel and deleting those fields?

Thanks

---

sorry for the late update. Here is the code i am using:

[a,patha]=uigetfile({'*.csv'},'Select the file' ,'c:\Data\2010'); 
file1=[patha a]; 

%# get a file ID 
fid = fopen(file1,'rt'); 
newf= textscan(fid, ['%s' repmat('%f',1,27)], 'HeaderLines', 1, 'Delimiter', ','); 
fclose(fid) ;

%//Make time a datenum of the first column
time = datenum(newf{1} );

%//Find the difference in minutes from each row
timeDiff = round(diff(datenum(time)*(24*60)));

%//the rest of the data
newf = cell2mat(newf(2:28));

the error i get is:

??? Error using ==> cat
CAT arguments dimensions are not consistent.

Error in ==> cell2mat at 81
            m{n} = cat(2,c{n,:});

Error in ==> testprogram at 31
pwr = cell2mat(newf(2:28));

it is due to the characters in my file i selected. it disappears when i manually delete them

解决方案

Textscan fails if the string doesn't match the expectation. The empty entries lead to problems when catenating - your array would have an uneven number of columns.

textscan('bla,5.4,missing,3,3,3.4','%s%f%f%f%f%f','Delimiter',',')

ans = 

    {1x1 cell}    [5.4000]    [0x1 double]    [0x1 double]    [0x1 double]    [0x1 double]

However, you can use'TreatAsEmpty', to treat 'missing' as empty (i.e. they're replaced by NaNs)

textscan('bla,5.4,missing,3,3,3.4','%s%f%f%f%f%f','Delimiter',',','TreatAsEmpty','missing')

ans = 

    {1x1 cell}    [5.4000]    [NaN]    [3]    [3]    [3.4000]

This allows you to run cell2mat without problems.

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