Calculate the uncertainty in components of composite model in Lmfit
There is not currently "an easy way of doing this" - the eval_uncertainty method belongs to the lmfit.ModelResult, not the lmfit.Model itself, at least partly because it needs the resulting covariance matrix.
But: I think eval_uncertainty method could probably calculate the uncertainty in any component models too.  I would suggest raising an Issue and/or using the lmfit mailing list to discuss making this change.
I have a model defined as
gmodel=Model(a)+Model(b)
result=gmodel.fit(data,...)
I use this model to fit the data, which gives me the parameters and their error estimates. Using the result.eval_components(), I could access the component a and component b of the model function. Also, using result.eval_uncertainty(), I could access the 1-sigma uncertainties in the model functions, which would be two lines. Now I want to know each component a and b in that 1-sigma uncertainty lines.Is there a easy way of doing this.