for循环浏览数据帧列表并将结果保存在新数据帧中

Question

I want to fetch some values out of a list of data frames and save the results in a new data frame. This is how my code looks:

for (i in 1:length(covpatient)){

    a <- names(covpatient[i])
    b <- sum(covpatient[[i]]$cov == 0)
    c <- sum(covpatient[[i]]$cov > 0 & covpatient[[i]]$cov <= 40)
    d <- sum(covpatient[[i]]$cov > 40 & covpatient[[i]]$cov <= 100)
    e <- sum(covpatient[[i]]$cov > 100)
    summary <- c(a,b,c,d,e)

}

So for every dataframe in the list covpatient, I want to create a summary variable which consists of 5 elements (a,b,c,d,e). Then I want to make a new data.frame which stores all summary values (5 columns & i rows).

Could someone give me a hand?

Answer 1

One way is to use lapply with rbind and then call as.data.frame . Since there is no data to play with, I'll give the general idea.

o <- lapply(1:length(covpatient), function(i) {
    a <- names(covpatient[i])
    b <- sum(covpatient[[i]]$cov == 0)
    c <- sum(covpatient[[i]]$cov > 0 & covpatient[[i]]$cov <= 40)
    d <- sum(covpatient[[i]]$cov > 40 & covpatient[[i]]$cov <= 100)
    e <- sum(covpatient[[i]]$cov > 100)
    c(a,b,c,d,e)
})
out <- as.data.frame(do.call(rbind, o))