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Information can be found in CRSP/COMPUSTAT MERGED DATABASE GUIDE Change Identifiers: Ticker: can be reassign to another company - abbreviation used to uniquely identify publicly-traded shares of a stock CUSIP: A company can have multiple CUSIPS due to structural changes.

more information can be found in URSA Labs This example is from Arrow Vignettes arrow best when working with big data Prep library("arrow", warn.conflicts = FALSE) library("dplyr", warn.conflicts = FALSE) check if S3 support is included.

Packages #install.packages("doParallel") library("doParallel") ## Loading required package: foreach ## Loading required package: iterators ## Loading required package: parallel Check how long a loop takes start <- proc.time() for (i in 1:10){ sqrt(i) } base_loop=(proc.

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