String Formatting

Topics: string, format

String formatting in R is typically done using the paste() or paste0() functions to combine text and variables, and sprintf() for formatted numeric output.

Using paste() and paste0()

name      <- "Dr. Santos"
diagnosis <- "Hypertension"

message <- paste("Patient seen by", name, "with", diagnosis)
print(message) 

# Output
# "Patient seen by Dr. Santos with Hypertension"

To format numbers (e.g., decimals), use sprintf():

glucose       <- 92.457
formatted_msg <- sprintf("Fasting blood glucose: %.1f mg/dL", glucose)
print(formatted_msg)   # Fasting blood glucose: 92.5 mg/dL

Cleaning Text with Base R

R includes functions to clean or modify text — perfect for cleaning patient notes or survey entries.

text <- "  Hypertension Stage II  "

print(toupper(text))                           # "  HYPERTENSION STAGE II  "
print(tolower(text))                           # "  hypertension stage ii  "
print(trimws(text))                            # "Hypertension Stage II" (removes whitespace)
print(gsub("Stage II", "Stage I", text))       # "  Hypertension Stage I  " (Replaces text)

Splitting and Joining

medications <- "Aspirin,Metformin,Lisinopril"
med_list    <- strsplit(medications, ",")[[1]]        # Split into a vector
rejoined    <- paste(med_list, collapse = " | ")      # Join back with a separator

print(med_list)                                       # "Aspirin"    "Metformin"  "Lisinopril"
print(rejoined)                                       # "Aspirin | Metformin | Lisinopril"

String formatting helps you present data in clear, readable, and professional ways — whether you’re summarizing patient data, generating reports, or printing analysis results. Clean text formatting is essential in medical reporting and data communication.

Named Lists Control structures