How do I get and index to a row (comparing a string to a column of the table) in a table as I could with strmatch?

We are supposed to replace strmatch because is becomes obsolete. But I currently use it to find the row index in a table where a unique ID identifies the row I want to modify:

 >>rowidx = strmatch(  '7890808.20180808',MRSresultsTable.Spectro_Study_ID)
 rowidx =
     1
     2

Now with the suggested replacement of strmatch this does not work:

 >> rowidx = strncmp(  '7620408.20170130',MRSresultsTable.Spectro_Study_ID, 16)
 rowdy = 
    []

[Duncan Lilley]

Hello,

It is worth noting that all of the recommend replacements for "strmatch" function slightly differently than "strmatch" itself. The "strmatch" function determines the indices of the second parameter which begin with the first parameter. If you intend to check if an ID matches exactly, then I would recommend using "strcmp".

It is also important to note that "strcmp" and "strncmp" return different outputs than "strmatch". Both "strcmp" and "strncmp" return a logical array, where a 1 indicates a match for that index and a 0 indicates no match. You can use "find" to get the indices of the strings that match.

Here are a few questions I have about your question:

• What is "rowdy"? It appears that you are saving the results of "strncmp" to a different variable ("rowidx") than you are displaying.
• You are using a different string in each of the examples your posted ('7890808.20180808' compared to '7620408.20170130'). Does the second string exist within your table?

Answer 1

[Jan]

The replacement of

rowidx = strmatch('7890808.20180808', MRSresultsTable.Spectro_Study_ID)

by

rowidx = find(strncmp('7890808.20180808', MRSresultsTable.Spectro_Study_ID, 16)

is valid and give the same results.

The output "rowdy = []" must be something else, because strncmp replies an empty vector only, if one of the inputs is empty also.