Compute BMI using standard formula

simple_bmi Computes BMI using standard formula. Assumes input compatible with output from longwide().

Usage

simple_bmi(wide_df, wtcol = "wt", htcol = "ht")

Arguments

wide_df

A data frame or data table containing heights and weights in wide format, e.g., after transformation with longwide()

wtcol

name of the weight value column (kg), default 'wt'

htcol

name of the height value column (cm), default 'ht'

Value

Returns a data table with the added column "bmi"

Examples

# \donttest{
# Simple usage
# Run on a small subset of given data
df <- as.data.frame(syngrowth)
df <- df[df$subjid %in% unique(df[, "subjid"])[1:2], ]
# cleangrowth() returns the data with an 'exclude' column
clean_df <- cleangrowth(df)
#> Warning: POSSIBLE SEX CODING ERROR in cleangrowth(): every value in `sex` is 1, which growthcleanr reads as female. If these subjects are male with 1 = male, 2 = female coding, they will be read as the wrong sex: pass sex_coding = list(male = 1, female = 2). If they are female, pass sex_coding = list(male = 0, female = 1) or code sex as F to remove this warning.
#> [15:46:14] growthcleanr: cleaning in progress — 2 subjects, 57 measurements, 1 batch of up to 5,000 subjects
#> ************************************************************
#> growthcleanr cleaning summary  (57 measurements)
#>   Weight      : 28 included (77.8%), 8 excluded (22.2%)
#>   Height      : 18 included (85.7%), 3 excluded (14.3%)
#>   Set aside   : 0 (0.0%)
#> ************************************************************
# Convert to wide format
wide_df <- longwide(clean_df)
#> Warning: POSSIBLE SEX CODING ERROR in longwide(): every value in `sex` is 1, which growthcleanr reads as female. If these subjects are male with 1 = male, 2 = female coding, they will be read as the wrong sex: pass sex_coding = list(male = 1, female = 2). If they are female, pass sex_coding = list(male = 0, female = 1) or code sex as F to remove this warning.
wide_df_with_bmi <- simple_bmi(wide_df)

# Specifying different column names; note that quotes are used
colnames(wide_df)[colnames(wide_df) %in% c("wt", "ht")] <-
  c("weight", "height")
wide_df_with_bmi <- simple_bmi(wide_df, wtcol = "weight", htcol = "height")
# }