Peak selection

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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:

Peaks with XEASY color code (an integer number) between cmin and cmax.
Peaks between dmin and dmax ppm from the diagonal.
Peaks that are assigned to conformation-independent distances.
Select randomly only a fraction p of all peaks that would normally be selected. This option can be useful when simulating peak lists.
Peaks between residues that are between m and n residues apart.
Peaks with distance limit between dmin and dmax.
Select only peaks that were read from the peak list with the given filename (with extension).
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.
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.
Peaks with peak numbers between m and n.
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.
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 where ωik and ωjk are the chemical shift coordinates of the two peaks in dimension k, and Δωk is the chemical shift tolerance for dimension k, as defined by the variable tolerance.
Peaks with shift in dimension 1 between pmin and pmax.
Peaks with shift in dimension 2 between pmin and pmax.
Peaks with shift in dimension 3 between pmin and pmax.
Peaks with shift in dimension 4 between pmin and pmax.
Peaks with quality factor between qmin and qmax.
Peaks with volume between Vmin and Vmax.
Peaks that correspond to conformation de¬pendent distances.


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:


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.