Hi,

I have a table and a vector, e.g.,

Table =

```
A B C
s1 0 1 2
s2 1 2 1
s3 2 0 1
```

Vector:

```
vec <- c(0.01, 0.087, 0.34)
```

I wish to iterate over the table to isolate pairs of rows and then use the vector to fit a 1st order linear regression model `(Y~A*B)`

. My problem is that I wish to initiate a matrix outside the main for loop and append the variable 'p_value' to that matrix after each iteration.

The code to isolate the p-values is given below:

```
for (rows in 1:nrow(Table)) {
li_row <- Table[rows,] # Extract a single row
row <- unlist(li_row) # Convert to vector
for (other in 1:nrow(Table[2, ])) {
li_row_2 <- Table[other,] # Extract a different single row
row_2 <- unlist(li_row_2)
lin_reg <- lm(vec ~ row*row2) # Call 1st order linear model
summ <- summary(lin_reg) # Store results summary
f_stat <- summ$fstatistic # Extract F-statistic data
p_value <- fstat[1] # Extract p-value [**The value to append to matrix**]
}
}
}}
```

In short, upon each iteration, I wish to add the 'p-value' to a matrix. I know a priori how big the matrix will be and also know what labels to attach to rows and columns.

Thanks,

S ;-)

What are you expecting 1:nrow(Table[2, ]) to evaluate to? This is the same as asking for 1:NULL because Table[2, ] is a vector and has nrow of NULL