我无法理解为什么我的nlsList（）模型是空的：我使用一个相当简单的公式在分组数据上运行它，并且R运行顺利（没有返回错误消息）但我最终得到一个空模型，长度为0且列出0个对象。我正在使用以下代码：
datagroupEg<-groupedData(BAI~B_A|ID,data=dataEg)
nlssubmodE<-nlsList(data=datagroupEg,
start=c(a=1,b=0,c=0.1),
BAI~(a*(B_A)^(b)-c*B_A)|ID,
na.action=na.exclude)
如果您想将此代码用于自己的运行，以下是我的数据示例，一个图：
BAI B_A ID
3.309294 3.309294e+00 01152b6
5.039944 8.349238e+00 01152b6
7.449806 1.579904e+01 01152b6
16.456000 3.225504e+01 01152b6
15.528190 4.778323e+01 01152b6
16.053870 6.383710e+01 01152b6
15.669560 7.950666e+01 01152b6
19.464130 9.897079e+01 01152b6
16.989930 1.159607e+02 01152b6
18.556510 1.345172e+02 01152b6
24.197300 1.587145e+02 01152b6
45.810370 2.045249e+02 01152b6
37.383950 2.419089e+02 01152b6
27.601330 2.695102e+02 01152b6
16.126370 2.856366e+02 01152b6
12.092800 2.977294e+02 01152b6
9.903305 3.076327e+02 01152b6
33.427950 3.410606e+02 01152b6
17.894750 3.589554e+02 01152b6
29.479190 3.884345e+02 01152b6
40.809790 4.292443e+02 01152b6
54.409670 4.836540e+02 01152b6
67.268610 5.509226e+02 01152b6
73.224360 6.241470e+02 01152b6
51.419880 6.755669e+02 01152b6
65.215640 7.407825e+02 01152b6
103.824800 8.446073e+02 01152b6
80.600480 9.252078e+02 01152b6
89.416630 1.014624e+03 01152b6
142.442900 1.157067e+03 01152b6
206.419500 1.363487e+03 01152b6
422.451100 1.785938e+03 01152b6
478.865100 2.264803e+03 01152b6
421.416500 2.686220e+03 01152b6
487.037500 3.173257e+03 01152b6
592.265300 3.765522e+03 01152b6
550.156400 4.315679e+03 01152b6
581.952300 4.897631e+03 01152b6
626.954900 5.524586e+03 01152b6
720.172300 6.244758e+03 01152b6
667.376700 6.912135e+03 01152b6
832.181400 7.744316e+03 01152b6
595.570200 8.339887e+03 01152b6
977.112900 9.316999e+03 01152b6
1201.168000 1.051817e+04 01152b6
1349.396000 1.186756e+04 01152b6
1413.715000 1.328128e+04 01152b6
1536.852000 1.481813e+04 01152b6
1376.806000 1.619494e+04 01152b6
1524.419000 1.771936e+04 01152b6
1806.174000 1.952553e+04 01152b6
2199.197000 2.172473e+04 01152b6
2470.713000 2.419544e+04 01152b6
2347.842000 2.654328e+04 01152b6
1827.753000 2.837103e+04 01152b6
1115.305000 2.948634e+04 01152b6
1138.944000 3.062528e+04 01152b6
1604.252000 3.222954e+04 01152b6
2952.124000 3.518166e+04 01152b6
3723.040000 3.890470e+04 01152b6
4666.516000 4.357122e+04 01152b6
3830.507000 4.740172e+04 01152b6
4041.905000 5.144363e+04 01152b6
4250.333000 5.569396e+04 01152b6
4391.673000 6.008563e+04 01152b6
4596.362000 6.468200e+04 01152b6
4644.586000 6.932658e+04 01152b6
4238.911000 7.356549e+04 01152b6
5422.298000 7.898779e+04 01152b6
4935.056000 8.392285e+04 01152b6
4861.407000 8.878425e+04 01152b6
3918.738000 9.270299e+04 01152b6
4494.930000 9.719792e+04 01152b6
4037.130000 1.012351e+05 01152b6
5568.663000 1.068037e+05 01152b6
4609.827000 1.114135e+05 01152b6
3454.036000 1.148676e+05 01152b6
3182.870000 1.180504e+05 01152b6
3901.029000 1.219515e+05 01152b6
5461.940000 1.274134e+05 01152b6
6442.759000 1.338562e+05 01152b6
6318.634000 1.401748e+05 01152b6
4877.958000 1.450528e+05 01152b6
3658.965000 1.487117e+05 01152b6
5234.990000 1.539467e+05 01152b6
7865.740000 1.618125e+05 01152b6
7620.812000 1.694333e+05 01152b6
7114.748000 1.765480e+05 01152b6
4915.308000 1.814633e+05 01152b6
4667.701000 1.861310e+05 01152b6
5628.113000 1.917591e+05 01152b6
6858.271000 1.986174e+05 01152b6
7760.036000 2.063775e+05 01152b6
6147.453000 2.125249e+05 01152b6
7782.232000 2.203071e+05 01152b6
4735.618000 2.250428e+05 01152b6
4903.610000 2.299464e+05 01152b6
5408.692000 2.353551e+05 01152b6
4917.325000 2.402724e+05 01152b6
5072.124000 2.453445e+05 01152b6
6603.290000 2.519478e+05 01152b6