[R] Accomplishing a loop on multiple columns

[Nerak]

Many thanks! Never used lists before, but it’s a great solution! It works
very well!


Although, I have a next question concerning this. 
I want to know for which value (column) I have the maximal Rsquared.
Therefore, I unlist the LIST so that it’s written like a vector. 
The columns were always named in the same way. They always start with
results4$depth_ following by the number. The numbers are constructed as:
seq(1,10,0.1). But if the R squared values are now in 1 column, I don’t know
for which column they are calculated. So I made a new data frame with both
columns: 
R2 <- unlist(LIST)
Cvalue <- c(seq(1,10,0.1))
results5 <- data.frame(Cvalue,R2)

# I know I can calculate the max value of Rsquared by this way: 

max(results5$R2)

# now I want to know to which Cvalue this belongs. I would write it like
this: 
results5$Cvalue[which(results5$R2 == "max(results5$R2)")] 
# But I always get the solution: 
numeric(0)
# I don’t know if these Rsquared values are in a kind of format that this
doesn’t work? (I used before for similar things, and I know that for example
it cannot works if R recognises the values as a date)  Maybe because it’s
with decimals? I know that max(results5$R2) is in this example 0.6081547 and
I can see that that belongs to the Cvalue == 1.8. It works in the opposite
way. 
results5$R2[which(results5$Cvalue == "1.8")]
# But neither
results5$Cvalue[which(results5$R2 == "0.6081547")] 
# nor 
results5$Cvalue[which(results5$R2 == "max(results5$R2)")]
# works…




# I have an other question concerning accomplishing calculations on several
colums. Again, there is a loop involved… I don’t know if I should ask it in
this topic as well, because I don’t want to start to many kind of similar
topics. I searched in the helpforum but unfortunately I couldn’t find
something similar.

Again, I manage to do it for one column (with the use of the specific name
for this column).
In each columns, I have 60 values. But to compare it to another column, I
should reorganize the values. I want that value 2 becomes value 1, value 3
value 2 and so on.  The first value would be NA.
If I would do this for 1 column, I would do it like this:
results$newdepth[1] <- NA
for (t in 2:60)
{
results$newdepth[t] <- results$depth[t-1]
}

Like I mentioned before, the names of each column are constructed in the
same way: results$depth_ followed by a number (seq(1,10,0.1)).

So I don’t know how to manage to repeat this for all the columns at the same
time? I would think about a for loop with for example for  (i in 1:91)
because there are 91 columns, but then I don’t know how to say that it
should happen for each column. I was thinking about using this
for (u in 1:91)
{
results$newdepth [,u]<- results$depth [,u]
for (t in 2:60)
{
results$newdepth[,u][t] <- results$depth[,u] [t-1]
}}

But I can see that there are several reasons why a for loop like this cannot
work. (like [ ][ ], …) 
I just really cannot find an other manner to repeat a calculation or
something els on several columns...


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