How is the number of cases / number of controls distributed with respect to the age categories?
how would I add row number 1-15 in "ncontrols" column?
Welcome to the forum,
Screenshots are not very useful but here is a simple example .
dat1 <- data.frame(aa = sample(1:50, 20), bb = LETTERS[1:20])
sum(dat1[1:15, "aa"])
You might find this useful: FAQ
what do the "aa" and "bb" represent?
I have named my data set Q1.data, as it is question 1's data.
I want to sum the first 15 rows of data in the "ncontrols" or the 5th column
so should my code read:
dat1 <- data.frame(aa = Q1.data(1:15, 5), **bb = LETTERS[1:20] (???) **) (???)
sum(dat1[1:15, "aa"])
They are column names, corresponding to "agegp" or "ncontrols", etc.
No, let's say your data set is a data.frame called "mydata". All you need to do is
sum(mydata[1:15, "ncontrols"]
In English, this means we are selecting the column "ncontrols" and taking rows from 1 to 15 and summing those 15 numbers.
You might find the Wrangling and Data chapters of Preceptor’s Primer a handy intro.
Hi, for a reproducible example instead of a screenshot:
For grouping and summarising:
Summarise each group down to one row — summarise • dplyr (tidyverse.org)
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