2. CONTENT
INTRODUCTION
HAMMING DISTANCE
EXAMPLE OF HAMMING DISTANCE
LIMITATIONS OF HAMMING DISTANCE
EDIT DISTANCE
RULES FOR EDIT DISTANCE
EXAMPLE OF EDIT DISTANCE
HAMMING DISTANCE V/S EDIT DISTANCE
REFERENCES
3. INTRODUCTION
It is the measure of distance between sequences,
which allow us to infer their similarities and related
biological functions.
The distance measure due to similarities suggest us
homology between the sequences.
It also help us to know the evolutionary
relationship.
Distance can be calculated by these methods –
Hamming distance
Edit distance
4. HAMMING DISTANCE
Hamming distance is the measure of dissimilarity
between two sequences i.e, the no. of positions at
which the corresponding character are different.
It measure the minimum no. of substitutions
required to change one character into the other.
It was introduced by RICHARD HAMMING in 1950.
6. LIMITATIONS OF
HAMMING DISTANCE
Both the sequences having same length.
Two sequences of unequal length having high
similarity will fail to align.
We can’t perform edit operation on any sequences.
Distance calculation of two sequences having
unequal length can be measured by an alternative
way called EDIT DISTANCE.
7. EDIT DISTANCE
Similarity between two sequences as minimum no.
of edit operation ( substitution, insertion & deletion )
needed to transform one to other.
Also called LEVENSHTEIN DISTANCE, developed by
VLADIMIR LEVENSHTEIN in 1966.
It gives an indication of how close two sequences
are, which are applicable for various purpose-
To find gene or protein that may have shared
functions or properties.
To infer family relationship & evolutionary tress over
different organism.
8. RULES FOR EDIT
DISTANCE
Edit operation (substitution & indel ) must be
performed on only one sequence.
It must not affect the length of the sequence.
Every character or gap of first sequence should be
align with every character or gap of other sequence.
10. HAMMING DISTANCE
V/S EDIT DISTANCE
Unlike hamming distance, edit distance allow us
to compare sequences of different length.
Hamming distance is a simple position by position
comparision while edit distance is formalised
through insertion and deletion operation.