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

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rbme17
rbme17 2019-8-17
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
Walter Roberson
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
rbme17 2019-8-17
编辑：rbme17 2019-8-17
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

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rbme17
rbme17 2019-8-20
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!

更多回答（2 个）

Walter Roberson
Walter Roberson 2019-8-17
  3 个评论
显示 1更早的评论
Walter Roberson
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
Walter Roberson 2019-8-20
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

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per isakson
per isakson 2019-8-17
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'}
>>
Don't you want to convert the numeric fields to double?
  1 个评论
rbme17
rbme17 2019-8-20
This was very close to what I needed. I ended up figuring out another way that worked well for me. Thanks!

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