Create a boolean column based on data in another column in R - r

Question

I have a data set and would like to do two things:
Set certain row values in Col A to 0 based on values in Col B
Create a new column with values of either 0 or 1 based on the edited values in Col A
My current approach is shown below - the issue is I occasionally get an error:
Error in `[<-.data.frame`(`*tmp*`, "OCS_dose", value = 0) :
replacement has 1 row, data has 0
As the numbers that I am generating are randomly selected and on certain trials there are no rows to update in Col A based on the numbers in Col B.
Here is an example of my code that causes the error:
pbo_IFNlow_data[pbo_IFNlow_data$OCS_status == 0,]['OCS_dose'] <- 0
OCS_status is either a 0 or 1 that is generated using:
pbo_OCS_status_low <- sample(c(0,1), replace = TRUE,
size = pbo_n_IFNlow, prob=c(1-.863, 0.863))
Therefore on occasion, I have no 0's... In my mind R should then just not try to update anything.
Is there a better way to do what I am trying to do?
Here is a more complete segment of my code:
pbo_OCS_status_low <- sample(c(0,1), replace = TRUE, size = pbo_n_IFNlow, prob=c(1-.863, 0.863)) #on OCS = 1
#OCS dose
pbo_OCS_dose_low <- rtruncnorm(pbo_n_IFNlow, a=0, b=Inf, mean=12.8, sd=8.1)
#IFN boolean flag
pbo_IFN_low <- rep(0, pbo_n_IFNlow)
#SLEDAI score
pbo_SLEDAI_low <- rtruncnorm(pbo_n_IFNlow, a=0, b=Inf, mean=11.1, sd=4.4)
#Response criteria met for SRI score reduction
pbo_SRI_low <- sample(c(0,1), replace = TRUE, size = pbo_n_IFNlow, prob=c(1-0.423, 0.423))
pbo_IFNlow_data <- cbind(IFN_status=pbo_IFN_low,
OCS_status=pbo_OCS_status_low,
OCS_dose=pbo_OCS_dose_low,
SLEDAI=pbo_SLEDAI_low,
SRI_response=pbo_SRI_low)
pbo_IFNlow_data <- data.frame(pbo_IFNlow_data)
#set those off OCS to 0
pbo_IFNlow_data[pbo_IFNlow_data$OCS_status == 0,]['OCS_dose'] <- 0
#stratifcation factor for OCS dosage
pbo_IFNlow_data$OCS_lessthan10 <- "temp"
pbo_IFNlow_data[pbo_IFNlow_data$OCS_dose < 10, ]['OCS_lessthan10'] <- 1
pbo_IFNlow_data[pbo_IFNlow_data$OCS_dose >= 10, ]['OCS_lessthan10'] <- 0
#stratification factor for SLE score
pbo_IFNlow_data$SLE_lessthan10 <- "temp"
pbo_IFNlow_data[pbo_IFNlow_data$SLEDAI < 10, ]['SLE_lessthan10'] <- 1
pbo_IFNlow_data[pbo_IFNlow_data$SLEDAI >= 10, ]['SLE_lessthan10'] <- 0

Answer 1

It would be easier if we can have a minimal reproducible example. If I understand your question correctly, you may want to try ifelse statement in R?
df <- data.frame(colA = seq(1, 10), colB = seq(11, 20))
# Set certain row values in Col A to 0 based on values in Col B
df$colA <- ifelse(df$colB > 15, 0, df$colB)
# Create a new column with values of either 0
# or 1 based on the edited values in Col A
df$colC <- ifelse(df$colA == 0, 1, 0)
print(df)
## colA colB colC
## 1 11 11 0
## 2 12 12 0
## 3 13 13 0
## 4 14 14 0
## 5 15 15 0
## 6 0 16 1
## 7 0 17 1
## 8 0 18 1
## 9 0 19 1
## 10 0 20 1