R method is as follows:
library(haven)
filename_base = 'YourFilenameWithoutCSVextension'
filename=paste(filename_base,'.csv',sep="")
df<-read.csv(filename)
xportname<-paste(filename_base,'.xpt',sep="")
write_xpt(data=df,path=xportname)
Python method is as follows:
import panda as pd
import xport.v56
df = pd.read_csv('file.csv')
with open('file.xpt'),'wb') as f:
xport.v56.dump(df,f)
Below is an app to do this automatically; it is an app to convert CSV to XPT, XPT to CSV, CSV to Mat, Mat to CSV, CSV to xlsx, and xlsx to CSV.