  This paper uses the theory of dual equivalence graphs to give explicit Schur
expansions for several families of symmetric functions. We begin by giving a
combinatorial definition of the modified Macdonald polynomials and modified
Hall-Littlewood polynomials indexed by any diagram $\delta \subset {\mathbb Z}
\times {\mathbb Z}$, written as $\widetilde H_{\delta}(X;q,t)$ and $\widetilde
H_{\delta}(X;0,t)$, respectively. We then give an explicit Schur expansion of
$\widetilde H_{\delta}(X;0,t)$ as a sum over a subset of the Yamanouchi words,
as opposed to the expansion using the charge statistic given in 1978 by Lascoux
and Sch\"{u}ztenberger. We further define the symmetric function
$R_{\gamma,\delta}(X)$ as a refinement of $\widetilde H_{\delta}(X;0,t)$ and
similarly describe its Schur expansion. We then analyze $R_{\gamma,\delta}(X)$
to determine the leading term of its Schur expansion. We also provide a
conjecture towards the Schur expansion of $\widetilde H_{\delta}(X;q,t)$. To
gain these results, we use a construction from the 2007 work of Sami Assaf to
associate each Macdonald polynomial with a signed colored graph
$\mathcal{H}_\delta$. In the case where a subgraph of $\mathcal{H}_\delta$ is a
dual equivalence graph, we provide the Schur expansion of its associated
symmetric function, yielding several corollaries.
