How to specifically select cluster on Featurescatter on Seurat? Nowadays, I am trying to calculate Pearson correlation values between two genes of my interest from single-cell RNA-data (features.tsv, barcodes.tsv, and matrix.mtx files) which are obtained from the 10xgenomics cellranger. 

FYI, The filtered_feature_bc_matrix includes an aggregated population of tumor-infiltrating immune cells that are derived from 6 different syngeneic mouse tumors (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE121861). I downloaded fastq files and ran "cellranger count" and "cellranger aggr" commands to obtain combined data.

My strategy includes the use of the "feature scatter" function deposited in the library(Seurat). Finally, I ended up getting results below. 



My question is that can we select a specific cluster(s) or identity on this plot? For example, I want to see correlation values in cluster 2 only.
The usage of Feature scatter is as follows. 

FeatureScatter(
  object,
  feature1,
  feature2,
  cells = NULL,
  group.by = NULL,
  cols = NULL,
  pt.size = 1,
  shape.by = NULL,
  span = NULL,
  smooth = FALSE,
  combine = TRUE,
  slot = "data"
)

Do you know how to get the Pearson correlation of my two genes using Seurat? This is the best I can do.

Thank you.
You can use the cells argument to only display the data for a specific subset of cells.  

For example to extract the values for a cluster 2:

# The cluster identity is stored in the meta.data
# In this example there is a clustering column called "RNA_snn_res.0.7" 
# but any metadata column can be used

clust2.cells &lt;- rownames(Seurat.data@meta.data[Seurat.data$RNA_snn_res.0.7 == 2, ])

FeatureScatter(Seurat.data, feature1 = "gene_A", feature2 = "gene_B", cells = clust2.cells)