Extract Text and Values from String

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Chad
Chad 2025-4-23
回答： Walter Roberson 2025-4-23
Dear Forum,
I am trying to extract the following information from this string.
str = 'AB(16.7)CD[20.6]EF[.1] 864.4 Round'
The first thing I did is the following.
vals1 = strsplit(str)
I get as expected.
{'AB(16.7)CD[20.6]EF[.1]'} {'864.4'} {'Roundl'}
What I am having trouble is trying to get the next part.
type1 = AB
val1 = 16.7
type2 = CD
val2 = 20.6
type3 = EF
val3 = .1
If I set
str1 = 'AB(16.7)CD[20.6]EF[.1]'
I can only get this to work
val1 = regexp(str1, '(?<=[)\d+\.\d(?=)','match','once')
val1 = '20.6'
What I don't understand is that is if str1 = 'AB(16)CD[20.6]EF[.1]'
Where there is no decimal I get an error.
I am unsure how to achieve the the text [type1,type2,type3] and three values [val1,val2,val3]

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采纳的回答

Matt J
Matt J 2025-4-23
编辑：Matt J 2025-4-23
Ran in:
str = 'AB(16.7)CD[20.6]EF[.1] 864.4 Round';
S=strsplit(str,{'(',')','[',']',' '});
Types=S([1,3,5])
Types = 1x3 cell array
{'AB'} {'CD'} {'EF'}
Vals=str2double(S([2,4,6]))
Vals = 1×3
16.7000 20.6000 0.1000
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更多回答（2 个）

Image Analyst
Image Analyst 2025-4-23
Ran in:
How much does the string vary? Are all the things at fixed, specific locations? If so just use indexing
str = 'AB(16.7)CD[20.6]EF[.1] 864.4 Round';
type1 = str(1:2);
val1 = str2double(str(4:7))
val1 = 16.7000
type2 = str(9:10)
type2 = 'CD'
val2 = str2double(str(12:15))
val2 = 20.6000
type3 = str(17:18)
type3 = 'EF'
val3 = str2double(str(20:21))
val3 = 0.1000
Sure, it's not as compact as some regexp but way less cryptic and far easier to understand.
If the values and types are not in fixed index locations, you should look at using the more modern patterns instead of the older (and more cryptic/harder to use) regexp function. Also see extract as shown in the examples for digitsPattern and lettersPattern
patNum = digitsPattern;
numbers = extract(str,patNum)
numbers = 7x1 cell array
{'16' } {'7' } {'20' } {'6' } {'1' } {'864'} {'4' }
You would then have to use str2double and combine cells that you know belong as parts of the same number, like
val1 = str2double(numbers{1}) + str2double(numbers{2}) / 10
val1 = 16.7000
val2 = str2double(numbers{3}) + str2double(numbers{4}) / 10
val2 = 20.6000
val3 = str2double(numbers{5}) / 10
val3 = 0.1000
patLetters = lettersPattern;
letters = extract(str,patLetters)
letters = 4x1 cell array
{'AB' } {'CD' } {'EF' } {'Round'}
type1 = letters{1}
type1 = 'AB'
type2 = letters{2}
type2 = 'CD'
type3 = letters{3}
type3 = 'EF'
Documentation for lettersPattern
Documentation for digitsPattern
Again, perhaps not as compact as regexp but I'd go for understandability, readability, and intuitiveness over compactness every time.
Walter Roberson
Walter Roberson 2025-4-23
Ran in:
strs = {'AB(16.7)CD[20.6]EF[.1]', 'AB(16)CD[20.6]EF[.1]'};
for idx = 1 : length(strs)
str1 = strs{idx};
info = regexp(str1, '^(?<type1>\w+)\((?<val1>(\d+(\.\d*)?|\.\d+))\)(?<type2>\w+)\[(?<val2>(\d+(\.\d*)?|\.\d+))\](?<type3>\w+)\[(?<val3>(\d+(\.\d*)?|\.\d+))\]', 'names', 'once')
end
info = struct with fields:
type1: 'AB' val1: '16.7' type2: 'CD' val2: '20.6' type3: 'EF' val3: '.1'
info = struct with fields:
type1: 'AB' val1: '16' type2: 'CD' val2: '20.6' type3: 'EF' val3: '.1'

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