nsel

Mapdl.nsel(type_='', item='', comp='', vmin='', vmax='', vinc='', kabs='', **kwargs)

Selects a subset of nodes.

APDL Command: NSEL

Note

Starting with PyMAPDL v0.66.0, you can use “P” as a second argument to select entities interactively. A window pops up allowing you to select, unselect, add or reselect entities depending on the first argument type_. An array with the ids of new selection is returned when the window is closed.

You can switch between selecting and unselecting pressing the keyboard key U.

Parameters:

type_

Label identifying the type of select:

S

Select a new set (default).

R

Reselect a set from the current set.

A

Additionally select a set and extend the current set.

U

Unselect a set from the current set.

ALL

Restore the full set.

NONE

Unselect the full set.

INVE

Invert the current set (selected becomes unselected and vice versa).

STAT

Display the current select status.

The following fields are used only with Type = S, R, A, or U:

Item

Label identifying data. Valid item labels are shown in the table below. Some items also require a component label. If Item = PICK (or simply “P”), graphical picking is enabled and all remaining command fields are ignored (valid only in the GUI). Defaults to NODE.

Comp

Component of the item (if required). Valid component labels are shown in the table below.

VMIN

Minimum value of item range. Ranges are node numbers, set numbers, coordinate values, load values, or result values as appropriate for the item. A component name (as specified on the CM (p. 338) command) may also be substituted for VMIN (VMAX and VINC are ignored).

VMAX

Maximum value of item range. VMAX defaults to VMIN for input values. For result values, VMAX defaults to infinity if VMIN is positive, or to zero if VMIN is negative.

VINC

Value increment within range. Used only with integer ranges (such as for node and set numbers). Defaults to 1. VINC cannot be negative.

KABS

Absolute value key:

• kabs = 0 - Check sign of value during selection.

• kabs = 1 - Use absolute value during selection (sign ignored)

Notes

Selects a subset of nodes. For example, to select a new set of nodes based on node numbers 1 through 7, do

>>> mapdl.nsel('S','NODE','',1,7)

The subset is used when the ‘ALL’ label is entered (or implied) on other commands, such as

>>> mapdl.nlist('ALL')

Only data identified by node number are selected. Data are flagged as selected and unselected; no data are actually deleted from the database.

When selecting nodes by results, the full graphics value is used, regardless of whether PowerGraphics is on.

Solution result data consists of two types, 1) nodal degree of freedom –results initially calculated at the nodes (such as displacement, temperature, pressure, etc.), and 2) element–results initially calculated elsewhere (such as at an element integration point or thickness location) and then recalculated at the nodes (such as stresses, strains, etc.). Various element results also depend upon the recalculation method and the selected results location [AVPRIN, RSYS, FORCE, LAYER and SHELL].

You must have all the nodes (corner and midside nodes) on the external face of the element selected to use Item = EXT.

This command is valid in any processor.

For Selects based on non-integer numbers (coordinates, results, etc.), items that are within the range VMIN-Toler and VMAX+Toler are selected. The default tolerance Toler is based on the relative values of VMIN and VMAX as follows:

If VMIN = VMAX, Toler = 0.005 x VMIN.

If VMIN = VMAX = 0.0, Toler = 1.0E-6.

If VMAX ≠ VMIN, Toler = 1.0E-8 x (VMAX-VMIN).

Use the SELTOL command to override this default and specify Toler explicitly.

Table: 208:: : NSEL - Valid Item and Component Labels

Table: 209:: : NSEL - Valid Item and Component Labels for Nodal DOF Result Values

Examples

Select nodes at x == 0, Of these, reselect nodes between 1 < Y < 10, then finally unselect nodes between 5 < Y < 6.

>>> mapdl.nsel('S', 'LOC', 'X', 0)
>>> mapdl.nsel('R', 'LOC', 'Y', 1, 10)
>>> mapdl.nsel('U', 'LOC', 'Y', 5, 6)

For other coordinate systems activate the coord system first. First, change to cylindrical coordinate system, select nodes at radius == 5. Reselect nodes from 0 to 90 degrees.

>>> mapdl.csys(1)
>>> mapdl.nsel('S', 'LOC', 'X', 5)
>>> mapdl.nsel('R', 'LOC', 'Y', 0, 90)

Note that the labels X, Y, and Z are always used, regardless of which coordinate system is activated. They take on different meanings in different systems Additionally, angles are always in degrees and NOT radians.

Select elements assigned to material property 2

>>> mapdl.esel('S', 'MAT', '', 2)

Select the nodes these elements use

>>> mapdl.nsle()

Reselect nodes on the element external surfaces

>>> mapdl.nsel('R', 'EXT')

Change to cylindrical coordinates

>>> mapdl.csys(1)

Reselect nodes with radius=5

>>> mapdl.nsel('R', 'LOC', 'X', 5)