How to use textscan on a cell array without a loop?

Question

rbme17 2019-8-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476483-how-to-use-textscan-on-a-cell-array-without-a-loop

评论： Walter Roberson 2019-8-20

Hi everyone!

So, I have a structure with multiple fields. One of the fields I filled with strings from multiple, fairly large text files (~100,000 lines), and it is now a cell array. Here's the layout of the structure, and a sample of mystruct.out.

mystruct = 
  1×5 struct array with fields:
    filename
    out
    size
    
mystruct.out = 
{'%ACCDA,50,123.99,W,07512.001,E,2,11,2.2,1002.2,Z,,,,*22' }
{'%ACCDA,50,123.99,W,04412.001,E,2,11,2.2,1002.2,Z,,,,*20' }
{'%ACCDA,50,123.99,W,07112.001,E,2,11,2.2,1002.2,Z,,,,*2A' }
{'%ACCDA,50,123.99,W,08512.001,E,2,11,2.2,1002.2,Z,,,,*2E' }
{'%ACCDA,50,123.99,W,06512.001,E,2,11,2.2,1002.2,Z,,,,*2B' }
...
...

I want to avoid using a loop to perform the following, but I haven't been able to figure out how to do so on a mass scale without a loop.

I want to be able to use textscan, or some other method, to store the delimited strings into a new cell array, inside of an new mystruct field (like *** below)

Note: 'ii' is an index I'm using in a separate loop, but it's irrelevant to this issue.

for nlr = 1:mystruct(ii).size
    fields = textscan(mystruct(ii).out{nlr},'%s','delimiter',',');
end
***(e.g. store into mystruct(ii).split(nlr))

How can I use textscan, or some other method, to "vectorize" the above loop?

Thanks!

2 个评论
显示无隐藏无

Walter Roberson 2019-8-17

I am a little confused about the sizes involved. Your show a 1x5 struct array, and 5 example output lines, but imply that there are more. Is it that case that mystruct(K).out is a 1 x 1 cell array containing a character vector for any given K? Or is mystruct(K).out an N x 1 cell array containing character vectors for any given K? If mystruct(K).out is an N x 1 cell array of character vectors, then should the data for each be processed separately, or can it all be put together into one big array ?

rbme17 2019-8-17

编辑：rbme17 2019-8-17

在 MATLAB Online 中打开

Hi Walter, sorry for the confusion.

The size of the structure varies, but in this case it could be expanded like so:

mystruct(1) =
  filename: some value
  out:      Nx1 array
  size:     some value
mystruct(2) = ... etc.

mystruct(K).out is an Nx1 cell array

I'm hoping to process each line of mystruct(K).out, from 1:N, and store it in the new structure field but without using a loop. Does that make more sense, or should I rephrase?

Thanks

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

rbme17 2019-8-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476483-how-to-use-textscan-on-a-cell-array-without-a-loop#answer_388333

编辑：rbme17 2019-8-20

Ok, so I actually ended up figuring something out that doesn't require textscan. I used the function 'split'.

Here's a shortened sample:

mystruct.out = {
        '%ACCDA,50,123.99,W,07512.001,E,2,11,2.2,1002.2,Z,,,,*22' 
        '%ACCDA,50,123.99,W,04412.001,E,2,11,2.2,1002.2,Z,,,,*20' };
s = split(mystruct(ii).out,',',1); 
s = 
    {'%ACCDA'   }    {'%ACCDA'   } 
    {'50'       }    {'50'       }    
    {'123.99'   }    {'123.99'   }    
    {'W'        }    {'W'        }    
    {'07512.001'}    {'04412.001'}   
    {'E'        }    {'E'        }   
    {'2'        }    {'2'        }    
    {'11'       }    {'11'       }  
    {'2.2'      }    {'2.2'      }   
    {'1002.2'   }    {'1002.2'   }    
    {'Z'        }    {'Z'        }   
    {0×0 char   }    {0×0 char   }    
    {0×0 char   }    {0×0 char   }    
    {0×0 char   }    {0×0 char   }    
    {'*22'      }    {'*20'      }   

Sorry if I wasn't clear enough in what I was asking, I was able to accomplish what I needed too so thank you all for your help!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Walter Roberson 2019-8-17

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476483-how-to-use-textscan-on-a-cell-array-without-a-loop#answer_387963

See my answer at https://www.mathworks.com/matlabcentral/answers/476452-splitting-one-column-into-multiple-columns# on how to process more efficiently.

3 个评论
显示 1更早的评论隐藏 1更早的评论

Walter Roberson 2019-8-20

textscan can process a character vector that has embedded newline characters, treating each as a separate line. The processing is quite efficient. This permits you to parse and convert each column of your input without having to loop sscanf or textscan over the cell entries. Give it a try.

Walter Roberson 2019-8-20

在 MATLAB Online 中打开

mystruct.out = [{'%ACCDA,50,123.99,W,07512.001,E,2,11,2.2,1002.2,Z,,,,*22' }
{'%ACCDA,50,123.99,W,04412.001,E,2,11,2.2,1002.2,Z,,,,*20' }
{'%ACCDA,50,123.99,W,07112.001,E,2,11,2.2,1002.2,Z,,,,*2A' }
{'%ACCDA,50,123.99,W,08512.001,E,2,11,2.2,1002.2,Z,,,,*2E' }
{'%ACCDA,50,123.99,W,06512.001,E,2,11,2.2,1002.2,Z,,,,*2B' }];
S = strjoin(mystruct.out, '\n');
fields_cell = textscan(S, '%s%f%f%s%f%s%f%f%f%f%s%s%s%s%s', 'Delimiter', ',');
fields_cell{5}
ans =
                  7512.001
                  4412.001
                  7112.001
                  8512.001
                  6512.001

请先登录，再进行评论。

Answer 3

per isakson 2019-8-17

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476483-how-to-use-textscan-on-a-cell-array-without-a-loop#answer_387971

在 MATLAB Online 中打开

Am I on the right track? Run

%%    
    mystruct.out = {
        '%ACCDA,50,123.99,W,07512.001,E,2,11,2.2,1002.2,Z,,,,*22' 
        '%ACCDA,50,123.99,W,04412.001,E,2,11,2.2,1002.2,Z,,,,*20' 
        '%ACCDA,50,123.99,W,07112.001,E,2,11,2.2,1002.2,Z,,,,*2A' 
        '%ACCDA,50,123.99,W,08512.001,E,2,11,2.2,1002.2,Z,,,,*2E' 
        '%ACCDA,50,123.99,W,06512.001,E,2,11,2.2,1002.2,Z,,,,*2B' };
%%
    chr = strjoin( mystruct.out, '\n' );
    cac = textscan( chr, repmat('%s',1,15), 'Delimiter',',' );

Inspect the result

>> cac{1}
ans =
  5×1 cell array
    {'%ACCDA'}
    {'%ACCDA'}
    {'%ACCDA'}
    {'%ACCDA'}
    {'%ACCDA'}
>> cac{3}
ans =
  5×1 cell array
    {'123.99'}
    {'123.99'}
    {'123.99'}
    {'123.99'}
    {'123.99'}
>> cac{15}
ans =
  5×1 cell array
    {'*22'}
    {'*20'}
    {'*2A'}
    {'*2E'}
    {'*2B'}
>> 