Python Programming for Biology: Bioinformatics and Beyond

(computing):

Unbiased estimate

(mathematics):

Underflow (computing):

Uniform distribution

(mathematics):

Union (mathematics):

Unit vector

(mathematics):

Unrooted tree

(bioinformatics):

Unsigned (computing):

Unstructured (molecular

biology):

deviation.

Short for data type, indicating what kind of computational data

structure is being referred to, whether a simple one like a

number, linear ones like text strings or lists, or complex

arbitrary objects.

The process of ensuring that the data types of any values are

correct for the kind of operation being performed, e.g. to ensure

that mathematical operations are only performed on numbers.

For a probability distribution which is described by a certain

parameter and where an estimate of the parameter is made by

observing the random variable. The estimate is unbiased if there

is no difference between its expected value (long-term average)

and the true parameter value.

The result of an arithmetic calculation that is too small in

magnitude to store in computer memory.

A totally flat, even distribution of values. For example in the

context of a generating random numbers all values are equally

likely.

With reference to sets of items, the total obtained by combining

all of the items into a larger set.

A vector of length one. Unit vectors are often constructed to

represent the direction, but not magnitude, of another vector.

A hierarchical branching data classification where there is no

root or base. For a phylogenetic tree this means that the ancestor

node is not explicitly represented.

With reference to numeric data types, a way of representing a

value without any sign (positive or negative) information.

A biological molecule is unstructured if it doesn’t adopt any

particular conformation, e.g. a protein which is highly dynamic

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Unsupervised learning

(computing):

Update (graphics):

Van der Waals

(chemistry):

Variable (computing):

Variable (molecular

biology):

Variance (mathematics):

Vector (mathematics):

Vector graphics

(computing):

Vector space

(mathematics):

and not folded into a compact shape.

The process by which some machine learning methods can

recognise patterns in data without the requirement for training

data of known classification or value.

With reference to graphical interfaces, to refresh the display to

reflect the state of the underlying data, i.e. to have a graphical

display that responds to changes.

The non-bond interaction that occurs between atoms by virtue

of their radii. At close distances the van der Waals force is

repulsive, as the atoms’ electrons resist being superimposed, but

at larger distances the interaction is attractive (albeit

diminishing), due to transient, uneven charge distributions.

A data slot that can contain many different values. Generally a

variable is a named item, i.e. a means of allocating a value with

a tag so that it can be referred to in an abstract way within a

program.

With reference to a biological molecule, the property of

changing rapidly during evolution, i.e. giving variations in a

protein or DNA sequence.

A measure of the amount of spread or variation in a set of

values, which is the square of the standard deviation. Calculated

as the average square difference between the values and the

mean.

An array of numbers used to specify the location of a point in a

space.

A way of creating a graphical display by describing the

underlying geometry of items (e.g. using points, lines and areas)

so that they can be rendered into an image of any size by

considering a particular view (lighting and orientation etc.).

An abstract space where any position may be reached using a

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View (computing):

Volume (signal