[R] Fill an empty matrix with a function

[David Winsemius]

> On Dec 4, 2016, at 4:43 AM, Maximilian Eckert <maximilian.eckert03 at gmail.com> wrote:
> 
> Dear Sir oder Madam,
> 
> 
> 
> I am currently writing my master thesis and I am struggling with R:
> 
> 
> 
> I have created an empty matrix (M) which has months as row.names and stocks
> as column.names and now I want to fill this matrix with values from another
> matrix (T). The matrix T has also months as row.names and stocks as
> column.names however here I have several  values for each month. Now I want
> to count the values which have values bigger or equal to zero (plus 1) and
> add them to my matrix M:
> 
> 
> 
> If I do it manually it would look like: 
> 
> 
> 
> M[,1] <- t(array((colSums(T[1:22,] > 0))+1))  #here in Matrix T I have 22
> values for the month January 

22 rows

> 
> M[,2] <- t(array((colSums(T[23:53,] > 0))+1)) #here in Matrix T I have 30
> values for the monh February 
> 

31 rows were indexed.

How are these rows labelled? What does rownames(M) produce?


> 
> 
> Is there a way to do this without a loop as I have a very large data set? I
> tried to merge it however it did not work:
> 
> 
> 
> merge.default(as.data.frame(M), as.data.frame(T), by = "row.names",
> function(x){colSums(T[,]>0)+1})
> 
> 

If you want code, then you need to provide enough (accurate) information to support such an effort. If this data is n a matrix then duplicate rownames are allow, but if it is a dataframe or if coerced to a data.frame than duplicates are not allowed.

> 
> Thank you very much,
> 
> 
> 
> Max 
> 
> 
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> 
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David Winsemius
Alameda, CA, USA