Find and Replace (MATLAB)

I am trying to find and replace text string before a comma and keep the data string after the comma. I have tried the wildcard '*' but it didn't work. I have 55 states to do this to. An example is 'Adak Island, AK' to just "AK".

repeats = ' , AK'

indices = strfind(repeats, 'AK')

indices = 4

using_replace = replace(repeats, ' , AK', 'AK')

nothing changed, the text string stayed the same. Any suggestions?

Answer 1

[Sean de Wolski]

strip(extractAfter('Adak Island, AK',","))

ans = 'AK'

And see the other fun methods of string to figure out how to manipulate the part you want

methods('string')

Methods for class string:

append          contains        eq              extractAfter    gt              issorted        lt              pad             reverse         startsWith      
cellstr         count           erase           extractBefore   insertAfter     join            matches         plus            sort            strip           
char            double          eraseBetween    extractBetween  insertBefore    le              ne              replace         split           strlength       
compose         endsWith        extract         ge              ismissing       lower           or              replaceBetween  splitlines      upper           

[Deborah Johnson]

The data did not change in the table.column. It wasn't replaced. I have been researching since last night. I have tried a variety of ways. I probably have to call up the table.column before doing this maybe?

I have tried extract, extractAfter, extractBefore, extractBetween, eraseBetween, I can do this in Excel but would really like to learn how to do it in Matlab.

[Sean de Wolski]

This will stick it back in as a new variable in the table called State

T = readtable('County_STATE.csv');
T.State = extractAfter(T.DISPLAY_AIRPORT_CITY_NAME_FULL,", ");

[Deborah Johnson]

Hello Sean,

This worked! All the rows were edited and only leaving the STATE name. I repeated the same step to verify and Thank You!

T.State = extractAfter(T.DISPLAY_AIRPORT_CITY_NAME_FULL,", ");

Answer 2

[Image Analyst]

Try this:

t = readtable('County_STATE.csv');
% Crop off null columns
t = t(:, 1:3);
% Extract State alone, and City alone.
State = extractAfter(t.DISPLAY_AIRPORT_CITY_NAME_FULL, ', ');
City = extractBefore(t.DISPLAY_AIRPORT_CITY_NAME_FULL, ', ');
% Add these on as columns in the table variable.
t = addvars(t, City, State, 'After','DISPLAY_AIRPORT_CITY_NAME_FULL')

t = 18×5 table
    AIRPORT            DISPLAY_AIRPORT_NAME             DISPLAY_AIRPORT_CITY_NAME_FULL         City          State 
    _______    _____________________________________    ______________________________    _______________    ______

    {'ADK'}    {'Adak NS'                          }         {'Adak Island, AK'}          {'Adak Island'}    {'AK'}
    {'ANC'}    {'Anchorage International'          }         {'Anchorage, AK'  }          {'Anchorage'  }    {'AK'}
    {'ADQ'}    {'Kodiak Airport'                   }         {'Kodiak, AK'     }          {'Kodiak'     }    {'AK'}
    {'AKN'}    {'King Salmon Airport'              }         {'King Salmon, AK'}          {'King Salmon'}    {'AK'}
    {'BET'}    {'Bethel Airport'                   }         {'Bethel, AK'     }          {'Bethel'     }    {'AK'}
    {'BRW'}    {'Wiley Post/Will Rogers Memorial'  }         {'Barrow, AK'     }          {'Barrow'     }    {'AK'}
    {'CDV'}    {'Cordova Mile 13'                  }         {'Cordova, AK'    }          {'Cordova'    }    {'AK'}
    {'DLG'}    {'Dillingham Airport'               }         {'Dillingham, AK' }          {'Dillingham' }    {'AK'}
    {'FAI'}    {'Fairbanks International'          }         {'Fairbanks, AK'  }          {'Fairbanks'  }    {'AK'}
    {'GST'}    {'Gustavus Airport'                 }         {'Gustavus, AK'   }          {'Gustavus'   }    {'AK'}
    {'JNU'}    {'Juneau International'             }         {'Juneau, AK'     }          {'Juneau'     }    {'AK'}
    {'KTN'}    {'Ketchikan International'          }         {'Ketchikan, AK'  }          {'Ketchikan'  }    {'AK'}
    {'OTZ'}    {'Ralph Wien Memorial'              }         {'Kotzebue, AK'   }          {'Kotzebue'   }    {'AK'}
    {'OME'}    {'Nome Airport'                     }         {'Nome, AK'       }          {'Nome'       }    {'AK'}
    {'ABI'}    {'Abilene Regional'                 }         {'Abilene, TX'    }          {'Abilene'    }    {'TX'}
    {'ABQ'}    {'Albuquerque International Sunport'}         {'Albuquerque, NM'}          {'Albuquerque'}    {'NM'}

Answer 3

[Image Analyst]

Why not just do this:

str = 'Adak Island, AK' ;
commaIndex = strfind(str, ',')

commaIndex = 12

if ~isempty(commaIndex)
    output = strtrim(str(commaIndex+1 : end))
else
    output = str % No comma in the string so just return the original.
end

output = 'AK'

[Sean de Wolski]

This is the old way predating string behavior in 2016b. I would not recommend it in modern versions.

[Deborah Johnson]

The data string in the table.column did not change. It was not replaced? Any suggestions?

[Image Analyst]

You gave us a character array. Please give us the data in the form of a table in a mat file with the paperclip icon so we can show you how to apply it to a table. Did you try just going down the column row by row?

[Deborah Johnson]

I have attached the file. I'm trying to edit the 3rd column to show just the STATE and remove/erase (extractAfter).

What am I not seeing?

Answer 4

[Steven Lord]

Functions like extract, extractAfter, etc. don't modify the variables that you pass in as input. If you were to specify those same variable names as the output argument for those calls then they would be modified.

fruit = "Apple, Banana, Cherry"

fruit = "Apple, Banana, Cherry"

The following call creates a new variable named justCherry and leaves the fruit variable with its original contents.

justCherry = extractAfter(fruit, "Banana, ")

justCherry = "Cherry"

fruit

fruit = "Apple, Banana, Cherry"

The following call overwrites the existing variable named fruit with the output of extractAfter, so fruit is different after the call.

fruit = extractAfter(fruit, "Banana, ")

fruit = "Cherry"

fruit

fruit = "Cherry"

Your original code using_replace = replace(repeats, ' , AK', 'AK') does not modify the repeats variable.

If you'd written repeats = replace(repeats, ' , AK', 'AK') that would overwrite the original contents of the repeats variable with the modified data returned by replace.

Answer 5

[Deborah Johnson]

I tried it when I got home and really appreciate your time and assistance! Thank You so much!