Repeated fields like `param` are lists in Python net spec, so define a list of dicts for separate learning rates and decays:
n.conv1 = L.Convolution(n.data, kernel_size=5, num_output=20, weight_filler=dict(type='xavier'),
param=[dict(lr_mult=1.0, decay_mult=1.0),dict(lr_mult=2.0, decay_mult=0.0)])
==
layer {
name: "conv1"
type: "Convolution"
bottom: "data"
top: "conv1"
param {
lr_mult: 1.0
decay_mult: 1.0
}
param {
lr_mult: 2.0
decay_mult: 0.0
}
convolution_param {
num_output: 20
kernel_size: 5
weight_filler {
type: "xavier"
}
}