MATLAB Answers

Unique values in an array, with specific digits

8 views (last 30 days)
Hi, I have an array of 7 digit numbers. i want to count the number of occurrences of unique values starting with two digits, say, 12*****. How can I do that? What about if I want to calculate the frequency of unique values ending with two specific digits, say, *****12?
To calculate unique occurrences for all values, the following works:
a = unique(input)
output = [a,histc(input(:),a)]
Any suggestions would be appreciated! Thanks!


Sign in to comment.

Accepted Answer

sushma sharma
sushma sharma on 27 Sep 2016
close, but not quite. while it lists the unique combinations of first and last digits, how can i get the frequency of each? e.g. count of numbers that begin with the digits 12 (12*****) and count of numbers ending with the digits 12 (e.g. *****12). any help would be appreciated! thank you!

  1 Comment

Sean de Wolski
Sean de Wolski on 29 Sep 2016
You have to use all of the outputs from unique
[uv,~,idx] = unique(...)
n = accumarray(idx,1)
uv n

Sign in to comment.

More Answers (1)

Sean de Wolski
Sean de Wolski on 27 Sep 2016
Edited: Sean de Wolski on 27 Sep 2016
Starting in R2016b this is much easier with the string class.
x = [1234; 1256; 1334]
s = string(x)
unique(extractBefore(s,3)) % First two
unique(reverse(extractBefore(reverse(s),3))) % Last two
In older releases:
% First two
% Last two


Sign in to comment.

Sign in to answer this question.