Peak selection

Peak selections are made with the peaks select command and consist of two atom selections that are separated by a comma. The comma may be omitted if both atom selections consist of a single atom name. Peak selections that contain blanks must be enclosed in double quotes.

In addition, peak selections may contain one or several of the following conditions:

colors=cmin..cmax

Peaks with XEASY color code (an integer number) between cmin and cmax.

diagonal=dmin..dmax

Peaks between dmin and dmax ppm from the diagonal.

fixed

Peaks that are assigned to conformation-independent distances.

fraction=p

Select randomly only a fraction p of all peaks that would normally be selected. This option can be useful when simulating peak lists.

levels=m..n

Peaks between residues that are between m and n residues apart.

limit=dmin..dmax

Peaks with distance limit between dmin and dmax.

list=filename

Select only peaks that were read from the peak list with the given filename (with extension).

list=m..n

Peaks that were read from peak lists m to n. Peak lists are numbered 1, 2,... in the order in which they have been read. Instead of a range specification, m..n, it is also possible to specify a single peak list number, m.

multiple=mode

Select individual assignments of an ambiguously assigned peak according to the given mode: multiple=individual selects assignments individually, as if they would belong to separate peaks; multiple=ifany selects all assignments of a peak if at least one assignment matches the selection; multiple=ifall selects all assignments of a peak only if all assignments match the selection; multiple=no selects all peaks that do not have multiple assignments.

numbers=m..n

Peaks with peak numbers between m and n.

ordered

Peaks for which the assignment in dimension 1 matches the first atom selection and the assignment in dimension 2 matches the second atom selection. If this option is not given, the two atom selections can match in any order.

overlap=doverlap

Peaks with a normalized distance to another peak shorter than doverlap. The normalized distance between two peaks, i and j, in an n-dimensional spectrum is defined by $\textstyle d={\sqrt {\sum _{k=1}^{n}\left({\frac {\omega _{ik}-\omega _{jk}}{\Delta \omega _{k}}}\right)^{2}}}$ where ωik and ωjk are the chemical shift coordinates of the two peaks in dimension k, and Δω_k is the chemical shift tolerance for dimension k, as defined by the variable tolerance.

ppm1=pmin..pmax

Peaks with shift in dimension 1 between pmin and pmax.

ppm2=pmin..pmax

Peaks with shift in dimension 2 between pmin and pmax.

ppm3=pmin..pmax

Peaks with shift in dimension 3 between pmin and pmax.

ppm4=pmin..pmax

Peaks with shift in dimension 4 between pmin and pmax.

quality=qmin..qmax

Peaks with quality factor between qmin and qmax.

volume=Vmin..Vmax

Peaks with volume between Vmin and Vmax.

variable

Peaks that correspond to conformation de¬pendent distances.

Examples

All peaks:

**

All assigned peaks:

"*, *"

All HA-HA peaks:

"HA, HA"

All peaks with backbone hydrogens (H, HA) of residues 20–50:

"H HA 20..50, *"

All peaks with a backbone hydrogen (H, HA) of residues 20–50 in the first dimension:

"H HA 20..50, * ordered"

All peaks between backbone protons of residues 20–50:

"H HA 20..50, H HA 20..50"

Peaks between side chain amides and methyls:

"AMIDE - H, METHYL"

Peaks read from a peak list called n15.peaks:

"** list=n15.peaks"

Peaks read from the second or third peak list:

"** list=2..3"

Peaks between 4.6 and 4.8 ppm in the second dimension:

"** ppm2=4.6..4.8

Select randomly 50% of all assigned peaks:

"*, * fraction=0.5"

Peaks with only long-range assignments:

"*, * level=5.. multiple=ifall"

The previously selected peaks and peaks with peak numbers 120–130:

"+ ** numbers=120..130"

The command peaks select can be used with the parameter info=full to check peak selections.