Mohere - 8 months ago 49

R Question

I am new to R but here I have a dataframe of multiple measurements of a couple of conditions, I would like to perform a nested loop over the columns of the same condition, test if they have two true measurements (not zero) at least, if so calculate the mean of these specific conditions in a new dataset.

`> sample <- list(c(8,0,12,5,0,11), c(15,5,0,10,12,13), c(1,1,0,3,0,9),`

c(11,9,8,0,4,7), c(12,5,5,0,9,0), c(1,7,2,0,8,0))

> sample <- as.data.frame(sample)

> colnames(sample) <- c("x.1","x.2","x.3","y.1","y.2","y.3")

> sample

x.1 x.2 x.3 y.1 y.2 y.3

1 8 15 1 11 12 1

2 0 5 1 9 5 7

3 12 0 0 8 5 2

4 5 10 3 0 0 0

5 0 12 0 4 9 8

6 11 13 9 7 0 0

My output dataset should ideally look like this:

`> Newsample`

x y

1 8 8

2 2 7

3 0 5

4 6 0

5 0 7

6 11 0

Answer

We define `f_rowmean`

function:

```
f_rowmean <- function(y) apply(y,1, function(x) ifelse(sum(x!=0)>=2, mean(x), 0))
```

And then:

```
data.frame(x=f_rowmean(sample[,grep("x", names(sample))]),
y=f_rowmean(sample[,grep("y", names(sample))]))
# x y
# 1 8 8
# 2 2 7
# 3 0 5
# 4 6 0
# 5 0 7
# 6 11 0
```

**EDIT**

As for OP's new problem statement (in comments), suppose your data set is in `df1`

, then you could do:

```
res.cols <- c("CAOV-3 Reg", "CAOV-3 Mod", "OVCAR-3Reg", "OVCAR-4Reg", "VOA1056Reg",
"VOA4698Reg", "VOA4698Mod", "TOV112DReg", "TOV112DMod", "TOV21G Mod",
"HCC38 Reg", "HCC38 Mod")
res <- setNames(data.frame(matrix(0,nrow(df1),length(res.cols))), res.cols)
res <- sapply(res.cols, function(x) res[,x] <- f_rowmean(df1[,grep(x, names(df1))]))
```

Source (Stackoverflow)