@Stefan Schippers In below testbench, W and L of nmos are varied using alterparam. I wanted to plot drain current

i(v1)

for for different W and L values hence used

i(v1)%1

to plot separate sweeps but it seems not giving desired plot.

Remove all set appendwrite lines and write each dc simulation into a different file, like test_nmos_sizes1.raw, test_nmos_sizes2.raw, ... then you can display i(V1) for different files, see example below:

While using marker on graph, can Y-axis values of each swept curve be available for particular X-axis value. For example, For vgs=1V want to see Ids value for all swept vds values in graph.

You can isolate a specific curve and see the current value, see video.

Thanks @Stefan Schippers for these solutions