SAS2R.ai

SAS to R Converter for Clinical Trial Programming

Back to Home

Convert SAS code to production-ready R

SAS2R.ai helps Statistical Programmers and Biostatisticians translate SAS programs into clean, readable R code—optimized for regulated analytics workflows and Shiny app development.

What it’s good for
  • DATA step style transformations and derivations
  • PROC SQL-style joins, filters, and summarizations
  • Shiny-ready R workflows (clean, modular code)
  • Clinical trial programming patterns (CDISC-aware mindset)
How to use
  1. Paste SAS code (or upload a .sas/.txt file)
  2. Click Convert
  3. Copy the generated R code and run it in your environment

FAQ

How do I convert SAS to R for clinical trial programming (SDTM/ADaM)?

Start by converting deterministic data preparation steps (joins, filters, derivations) and then apply a QC checklist (counts, keys, missingness, summaries). For SDTM/ADaM, validate controlled terminology, metadata, and derivations against your standards/SOPs.

Can I convert PROC SQL and DATA step code to R?

Yes—SAS2R.ai is designed to translate common clinical trial programming patterns (DATA steps, PROC SQL-style joins, filtering, derivations) into readable R code.

Does it convert PROC SQL joins to dplyr or data.table?

Typically yes. Many PROC SQL patterns map cleanly to dplyr joins (left_join/inner_join) or data.table merges. Always validate row counts and key uniqueness, especially for one-to-many joins.

How do I convert PROC SQL GROUP BY to R?

Most PROC SQL aggregations translate to dplyr group_by() + summarise(). Pay attention to missing values and whether SAS is implicitly converting types (e.g., character to numeric) in your source code.

How does it handle BY-group processing, FIRST./LAST., and lag/retain logic?

Common BY-group patterns can be expressed with group_by()/arrange() and dplyr verbs, and lag/lead equivalents. Stateful RETAIN-style logic may require careful review to ensure the R translation matches SAS row-order semantics.

How do I translate SAS MERGE + BY to R safely?

In R, you typically use explicit joins with keys (e.g., dplyr left_join). For SAS MERGE semantics, verify sort order/keys and decide how to handle duplicates; then validate the join cardinality and record counts after the merge.

Can it translate SAS formats/informats and labels?

When formats/informats are explicit, the output may translate them into factor labels, recode() maps, or parsing rules (e.g., dates). If your logic relies on custom formats, you may need to recreate the mapping in R for full fidelity.

What about PROC REPORT/PROC TABULATE/ODS outputs?

Tabulation and reporting logic can often be translated into tidyr/dplyr summaries, gt, flextable, or rmarkdown outputs. Complex ODS layout styling is usually best handled by rebuilding the report formatting in native R tooling.

How do I create TLFs in R (Tables, Listings, Figures) like SAS ODS?

A common approach is dplyr/tidyr for data prep plus gt or flextable for tables/listings, and ggplot2 for figures. For production, teams often render outputs via Quarto/R Markdown and keep formatting rules version-controlled.

Do you support clinical trial programming standards like CDISC (SDTM/ADaM)?

The converter is designed with a CDISC-aware mindset and common SDTM/ADaM derivation patterns in mind. You should still validate derivations, controlled terminology mappings, and dataset-level metadata per your standards and SOPs.

Can it help with SDTM domain programming in R (e.g., AE/DM/VS)?

Yes for many core patterns (mapping raw to SDTM variables, controlled terminology mapping, standardizing dates/times). You should still validate against your Define-XML/metadata and confirm domain-level rules (e.g., required variables, sorting) match expectations.

Can it help with ADaM dataset programming in R (e.g., ADSL/ADAE)?

It can accelerate common derivations (population flags, treatment dates, baseline/analysis windows) by translating deterministic logic. You should verify timing rules, windowing, and any sponsor-specific conventions through QC and review.

Can it help convert macros (e.g., %LET, %MACRO, %DO loops)?

Simple macro variables and straightforward macro control flow can often be mapped to R parameters and functions. Large macro libraries may need a staged approach: convert core data steps first, then refactor macros into reusable R functions.

How do I replace SAS macro variables (%LET) in R?

In R, macro variables are typically ordinary variables or function arguments. For repeatable pipelines, wrap logic in functions and pass parameters explicitly—this improves testability and reduces hidden state.

How does it handle missing values (SAS . vs R NA) and special missing (.A-.Z)?

R uses NA for missingness. If your SAS logic uses special missing values (.A-.Z) to encode reasons, you may need to preserve that explicitly (e.g., an additional flag variable) to keep downstream behavior identical.

Will the converted R code match SAS results exactly?

Often it can match closely, but exact parity depends on data types, sorting, missingness rules, and edge-case logic. Treat the output as a strong starting point and run row-level QC (counts, keys, summaries) before using in production.

Is this suitable for a regulated (GxP) environment and validation workflows?

It can accelerate development, but you remain responsible for verification and validation. Many teams use the output to speed up drafting, then apply standard code review, unit tests, QC checks, and documentation per SOP.

How do I operationalize this for a team (leads/managers)?

A practical approach is to standardize an R project template (packages, style, test strategy), define QC checklists for SAS↔R parity, and use code review gates so conversions are consistent across contributors.

What R packages does the output use?

It generally favors readable, maintainable idioms (often tidyverse-style), but the exact packages depend on your input code. You can align your team on preferred packages (e.g., dplyr vs data.table) and refactor accordingly.

Is the generated R code suitable for Shiny apps?

The output is generated with Shiny-readiness in mind: modular, explicit transformations, and clear separation of data preparation and presentation logic.

Can I use the output as a starting point for a Shiny dashboard?

Yes. A common workflow is to keep data prep in pure R functions (testable) and then call those functions inside Shiny server logic. This keeps your app maintainable and easier to validate.

Do you store my SAS code?

We follow a privacy-first approach and aim to minimize retention. See the Terms for details about processing and storage behavior.

What’s the best way to QC a SAS-to-R conversion?

Start with deterministic checks: row counts, key uniqueness, variable types, and missingness. Then compare summaries and spot-check subject-level records. For production, add automated tests and keep conversion notes for traceability.

Examples (SAS → R)

These are simplified templates to illustrate common translation patterns. Always validate against your standards, metadata, and edge cases.

PROC SQL LEFT JOIN → dplyr left_join()
SAS
proc sql;
  create table adsl as
  select a.usubjid,
         a.trt01p,
         b.age
  from dm as a
  left join demo as b
    on a.usubjid = b.usubjid;
quit;
R
library(dplyr)

adsl <- dm %>%
  left_join(demo, by = "usubjid") %>%
  select(usubjid, trt01p, age)
BY-group FIRST./LAST. → group_by() + arrange() + slice()
SAS
proc sort data=vs; by usubjid visitnum; run;

data vs_first;
  set vs;
  by usubjid;
  if first.usubjid;
run;
R
library(dplyr)

vs_first <- vs %>%
  arrange(usubjid, visitnum) %>%
  group_by(usubjid) %>%
  slice(1) %>%
  ungroup()
Macro loop idea → R function + lapply()
SAS
%macro make_domain(dom=);
  data &dom;
    set raw.&dom;
    /* ... derivations ... */
  run;
%mend;

%make_domain(dom=dm);
%make_domain(dom=ae);
R
library(dplyr)

make_domain <- function(dom, raw) {
  raw[[dom]] %>%
    mutate(/* ... derivations ... */)
}

domains <- c("dm", "ae")
out <- setNames(lapply(domains, make_domain, raw = raw), domains)
dm <- out$dm
ae <- out$ae
TLF table output pattern → gt (template)
SAS (ODS)
ods rtf file="t14_1_1.rtf";
proc report data=adsl nowd;
  columns trt01p age;
  define trt01p / group;
  define age / mean;
run;
ods rtf close;
R
library(dplyr)
library(gt)

tbl <- adsl %>%
  group_by(trt01p) %>%
  summarise(mean_age = mean(age, na.rm = TRUE), .groups = "drop") %>%
  gt() %>%
  tab_header(title = "Table 14.1.1", subtitle = "Mean Age by Treatment")
Shiny skeleton (starting point)
library(shiny)

ui <- fluidPage(
  titlePanel("SAS2R.ai — Shiny Prototype"),
  sidebarLayout(
    sidebarPanel(
      selectInput("trt", "Treatment", choices = NULL)
    ),
    mainPanel(
      tableOutput("summary")
    )
  )
)

server <- function(input, output, session) {
  # Populate choices from your prepared ADaM/SDTM data
  observe({
    updateSelectInput(session, "trt", choices = sort(unique(adsl$trt01p)))
  })

  output$summary <- renderTable({
    subset(adsl, trt01p == input$trt)
  })
}

shinyApp(ui, server)

SDTM / ADaM Conversion Checklist

Use this as a practical QA/validation guide when migrating clinical trial programming from SAS to R. It’s designed for both individual contributors and leads who need consistency across a team.

Foundations (always)
  • Inputs & provenance: confirm sources, snapshots, and cut dates match SAS runs.
  • Keys & uniqueness: verify primary keys (e.g., USUBJID + --SEQ) and duplicate handling.
  • Sorting & row-order logic: make explicit any SAS assumptions (BY groups, FIRST./LAST.).
  • Missingness: reconcile SAS missing vs R NA (and special missing if used).
  • Type fidelity: dates/times, character vs numeric, and categorical encodings.
Controlled terminology & formats
  • CT mapping: recreate SAS formats as explicit maps (lookup tables/recode rules).
  • Labels/metadata: decide how to store labels in R (attributes, metadata tables, or define-driven).
  • Edge cases: confirm behavior for unknown/other values and partial dates.
SDTM focus
  • Domain conformance: required variables present, expected sort order, and value-level rules.
  • Dates/times: ISO8601 construction and time zone conventions match your standards.
  • SUPPQUAL: ensure QNAM/QVAL logic is deterministic and traceable.
  • Traceability: keep clear derivation notes per variable/domain for review.
ADaM focus
  • Population flags: ITT/SAF/PP rules implemented identically and documented.
  • Windowing: baseline and analysis windows reproduce SAS logic (order matters).
  • Derivations: ensure analysis variables match spec (units, rounding, imputations).
  • Reproducibility: any randomization (if used) is seeded and controlled.
QC & governance (team-ready)
  • Parity checks: row counts, key uniqueness, and summary statistics vs SAS outputs.
  • Spot checks: subject-level comparisons for tricky derivations (dates, merges, censoring).
  • Automated tests: add unit tests for derivation functions and domain builders.
  • Code review gates: enforce style and QC checklist completion before merge.
  • Versioning: pin package versions and capture session info for auditability.
  • Deliverables: keep conversion notes (assumptions, decisions, and residual risks).