删除使用 as.formula 添加的空格

Question

我从文本创建公式，但生成的公式包含不需要的空格。有没有办法防止这种情况发生。

# text in which variables for formula are stored

mainEffectText ="age sex bmi cohort"
interactionText="age*cohort"

# get text into R

mainEffects <- read.table(textConnection(mainEffectText))
mainEffects <- t(mainEffects)
mainEffects <- as.character(mainEffects[,1])

interactions <- read.table(textConnection(interactionText))
interactions <- t(interactions)
interactions <- as.character(interactions[,1])


# put all terms into one vector
allTerms <- c(mainEffects,interactions)

# create formula
form <- as.formula(paste("Surv(time, event) ~ ",paste(allTerms, collapse=" +")))

这给出了以下内容，并在交互项中添加了空格：

form
# Surv(time, event) ~ age + sex + bmi + cohort + age * cohort

Answer 1

空格并不是真正的问题，但无论如何试试这个：

# inputs
mainEffectText <- "age sex bmi cohort"
interactionText <- "age*cohort"
lhs <- "Surv(time, event)"

both <- paste(mainEffectText, interactionText)
paste0(gsub(" ", "", lhs), "~", gsub(" ", "+", both))

给予：

"Surv(time,event)~age+sex+bmi+cohort+age*cohort"

如果输入是这种形式（lhs 同上），则使用：

# inputs
mainEffects <- c("age", "sex", "bmi", "cohort")
interactions <- "age*cohort"

both <- paste(paste(mainEffects, collapse = " "), 
              paste(interactions, collapse = " "))
paste0(gsub(" ", "", lhs), "~", gsub(" ", "+", both))