NMRPipe Processing Functions
LS: Left Shift and Zero Pad.
LS applies a left-shift to the points in each vector from the current dimension of the data. The shifted points at the start of the data vector are replaced with zeros. For example, if an 8-point data vector consists of the following values:
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0then after a 2-point left-shift (
LS -ls 2) the result will be:
3.0 4.0 5.0 6.0 7.0 8.0 0.0 0.0
The LS function will only shift by an integer number of points; for shifting data by a fractional number of points, use the FSH function.
Specifies the number of points for the shift. If the number is positive, the data will be shifted to the right. If it is negative, the data will be shifted to the left. This value can also be specified with spectral units (% Hz ppm). In these cases, the amount of shift requested will be rounded to the nearest integer.
If this flag is used with time-domain data, the recorded time-domain sizes NDAPOD and NDTDSIZE are adjusted by the number of points shifted. If this flag is used with frequency-domain data, the chemical shift calibration information is updated (NDORIG and NDCENTER).
The following, when applied in the time-domain, is equivalent to applying a first order phase of P1=360 in the frequency domain; applying the zero-fill before the LS avoids losing one point:
| nmrPipe -fn ZF -auto \ | nmrPipe -fn LS -rs 1 \
Shifting functions RS (right-shift, integer number of points) CS (circular-shift, integer number of points) FSH (circular-shift, fractional number of points) and phase-correction function PS which can be used to apply the equivalent of a circular shift in one domain by applying a first order phase correction in the other domain.