textscan: skipping rows with missing data

Question

Kendra Wright 2014-12-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/165162-textscan-skipping-rows-with-missing-data

编辑： per isakson 2014-12-3

I'm using textscan() to open large txt files. Every so often I get a line where the value in the third column is missing, so everything gets shifted and text scan stops reading the data and just returns everything up until this point. The data kind of looks like this, although really it's 5 string columns followed by 30 double columns. It doesn't seem to want to preserve my formatting which would make it easier to see but I think this is still helpful

    string   string   double   double   double
    string            double   double   double 
    string   string   double   double   double 
    string   string   double   double   double 
    string   string   double   double   double

Does anyone know a way to deal with that other than going in and manually deleting those incomplete lines from the individual text files?

4 个评论
显示 2更早的评论隐藏 2更早的评论

Kendra Wright 2014-12-2

Then when there is the bad line it has tab+ a few spaces in place of the missing strings

Thorsten 2014-12-3

It would be helpful if you post your file, or at least some of the lines with the different number of columns.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

per isakson 2014-12-2

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/165162-textscan-skipping-rows-with-missing-data#answer_161025

编辑：per isakson 2014-12-3

在 MATLAB Online 中打开

"columns are separated by tabs"

textscan should take care of missing data automagically! &nbspReplace 'Delimiter', ',' by 'Delimiter', ','\t' in these examples

    >> cac = textscan( 'abc,,1,2,3', '%s%s%f%f%f', 'Delimiter', ',' )
    cac = 
        {1x1 cell}    {1x1 cell}    [1]    [2]    [3]
    >> cac{2}
    ans = 
        {''}
    >>

and

    >> cac = textscan( 'abc,def,1,,3', '%s%s%f%f%f', 'Delimiter', ',' )
    cac = 
        {1x1 cell}    {1x1 cell}    [1]    [NaN]    [3]

&nbsp

"Then when there is the bad line it has tab+ a few spaces in place of the missing strings"

    >> cac = textscan( 'abc,    ,1,2,3', '%s%s%f%f%f', 'Delimiter', ',' )
    cac = 
        {1x1 cell}    {1x1 cell}    [1]    [2]    [3]
    >> cac{2}
    ans = 
        {''}

and

    >> cac = textscan( 'abc,def,1,    ,3', '%s%s%f%f%f', 'Delimiter', ',' )
    cac = 
        {1x1 cell}    {1x1 cell}    [1]    [NaN]    [3]

&nbsp

@Star's proposal: MultipleDelimsAsOne

    >> textscan( 'a b c,d e f,1,2,3', '%s%s%s%s%s%s%f%f%f' ...
               , 'Delimiter', ', ', 'MultipleDelimsAsOne', true )
    ans = 
      Columns 1 through 6
        {1x1 cell} {1x1 cell} {1x1 cell} {1x1 cell} {1x1 cell} {1x1 cell}
      Columns 7 through 9
        [1]    [2]    [3]

So far so good. However, with "b" missing

    textscan( 'a    c,d e f,1,2,3', '%s%s%s%s%s%s%f%f%f' ...
            , 'Delimiter', ', ', 'MultipleDelimsAsOne', true )
    ans = 
      Columns 1 through 6
        {1x1 cell} {1x1 cell} {1x1 cell} {1x1 cell} {1x1 cell} {1x1 cell}
      Columns 7 through 9
        [2]    [3]    [0x1 double]