Search for Text

Identify text in string arrays, character vectors, or cell arrays of character vectors with thecontains,startsWith, andendsWithfunction.

Create a string. Starting in R2017a, you can create strings using double quotes.

str ="Rosemary Jones"

str = "Rosemary Jones"

Determine whetherstrcontains the substringmary. Thecontainsfunction returns a logical1if it finds the substring any place within the string.

TF = contains(str,"mary")

TF =logical1

You can also use thestrfindfunction to find matching text.strfindreturns the index of the start of each match. In this case,strfindreturns5because theminmaryis the fifth character ofstr.

idx = strfind(str,"mary")

idx = 5

Find multiple matches withstrfind. When there are multiple matches,strfind指数作为一个数组返回。

idx = strfind(str,"s")

idx =1×23 14

Create a string array that contains many names. Determine which names contain the substringAnn. Thecontainsfunction returns a logical array that has a1whereverstrhas an element that containsAnn. To create a new string array that includes only the matches, index intostrwithTF.

str = ["Rosemary Ann Jones","Peter Michael Smith","Ann Marie Young"]

str =1x3 string"Rosemary Ann Jones" "Peter Michael Smith" "Ann Marie Young"

TF = contains(str,"Ann")

TF =1x3 logical array1 0 1

matches = str(TF)

matches =1x2 string"Rosemary Ann Jones" "Ann Marie Young"

Find the strings that begin withAnn.

TF = startsWith(str,"Ann");matches = str(TF)

matches = "Ann Marie Young"

Similarly, theendsWithfunction find strings that end with a specified piece of text.

You can also use thecontains,startsWith, andendsWithfunctions to determine whether character vectors contains text.

chr ='John Paul Jones'

chr = 'John Paul Jones'

TF = contains(chr,'Paul')

TF =logical1

TF = endsWith(chr,'Paul')

TF =logical0

Use thecontainsfunction to find text in rows of a string array.census1905contains a few rows of simulated census data for the year 1905. Each row contains a name, year of birth, and number of times that name was given in that year.

census1905 = ["Ann Mary","1905","230";"John","1905","5400";"Mary","1905","4600";"Maryjane","1905","304";"Paul","1905","1206"];

Find the rows where the name is equal toMary.

TF = (census1905(:,1) =="Mary");census1905 (TF,:)

ans =1x3 string"Mary" "1905" "4600"

Find the rows where the name is a variation ofMarywith thecontainsfunction.

TF = contains(census1905(:,1),"Mary");census1905 (TF,:)

ans =3x3 string"Ann Mary" "1905" "230" "Mary" "1905" "4600" "Maryjane" "1905" "304"

Replace Text

You can replace text in string arrays, character vectors, or cell arrays of character vectors with thereplacefunction.

Create a string. Replace the substringmarywithanne.

str ="Rosemary Jones"

str = "Rosemary Jones"

newStr = replace(str,"mary","anne")

newStr = "Roseanne Jones"

You can also replace text using thestrrepfunction. However, thereplacefunction is recommended.

newStr = strrep(str,"Jones","Day")

newStr = "Rosemary Day"

Create a string array that contains many names.

str = ["Rosemary Ann Jones","Peter Michael Smith","Ann Marie Young"]

str =1x3 string"Rosemary Ann Jones" "Peter Michael Smith" "Ann Marie Young"

Specify multiple names to replace.

oldText = ["Ann","Michael"]; newText = ["Beth","John"]; newStr = replace(str,oldText,newText)

newStr =1x3 string"Rosemary Beth Jones" "Peter John Smith" "Beth Marie Young"

Replace text in a character vector. You can usereplaceandreplaceBetweenwith character vectors, as well as with strings.

chr ='Mercury, Gemini, Apollo'

chr = 'Mercury, Gemini, Apollo'

replace(chr,'Gemini','Mars')

ans = 'Mercury, Mars, Apollo'

Replace text in a string array of file names. Append the file names to the address of a website. The file names contain spaces, but spaces cannot be part of web addresses. Replace the space character," ", with%20, which is the standard for web addresses.

str = ["Financial Report.docx";"Quarterly 2015 Details.docx";"Slides.pptx"]

str =3x1 string"Financial Report.docx" "Quarterly 2015 Details.docx" "Slides.pptx"

newStr = replace(str," ","%20")

newStr =3x1 string"Financial%20Report.docx" "Quarterly%202015%20Details.docx" "Slides.pptx"

附加file names to the address of a website.

filenames ="http://example.com/Documents/"+ newStr

filenames =3x1 string"http://example.com/Documents/Financial%20Report.docx" "http://example.com/Documents/Quarterly%202015%20Details.docx" "http://example.com/Documents/Slides.pptx"

Extract Text

Extract a substring from string arrays or character vectors with theextractAfter,extractBefore, andextractBetweenfunctions. Use these functions to extract different substrings that precede, follow, or occur between specified pieces of text.

Create a string array that contains file names. Extract the portions of the names afterC:\Temp\with theextractAfterfunction.

str = ["C:\Temp\MyReport.docx";"C:\Temp\Data\Sample1.csv";"C:\Temp\Slides.pptx"]

str =3x1 string"C:\Temp\MyReport.docx" "C:\Temp\Data\Sample1.csv" "C:\Temp\Slides.pptx"

filenames = extractAfter(str,"C:\Temp\")

filenames =3x1 string"MyReport.docx" "Data\Sample1.csv" "Slides.pptx"

Extract customer names from a string array that encodes the names within XML tags.

str = ["Elizabeth Day";"George Adams";"Sarah Young"]

str =3x1 string"Elizabeth Day" "George Adams" "Sarah Young"

names = extractBetween(str,"",“< / CustomerName >”)

names =3x1 string"Elizabeth Day" "George Adams" "Sarah Young"