[R] About calculating average values from several matrices

[lily li]

Thanks very much, it works. But how to round the values to have only 1
decimal digit or 2 decimal digits? I think by dividing, the values are
double type now. Thanks again.


On Tue, May 9, 2017 at 9:04 AM, Charles Determan <cdetermanjr at gmail.com>
wrote:

> If you want the mean of each element across you list of matrices the
> following should provide what you are looking for where Reduce sums all
> your matrix elements across matrices and the simply divided my the number
> of matrices for the element-wise mean.
>
> Reduce(`+`, mylist)/length(mylist)
>
> Regards,
> Charles
>
> On Tue, May 9, 2017 at 9:52 AM, lily li <chocold12 at gmail.com> wrote:
>
>> I meant for each cell, it takes the average from other dataframes at the
>> same cell. I don't know how to deal with row names and col names though,
>> so
>> it has the error message.
>>
>> On Tue, May 9, 2017 at 8:50 AM, Doran, Harold <HDoran at air.org> wrote:
>>
>> > It’s not clear to me what your actual structure is. Can you provide
>> > str(object)? Assuming it is a list, and you want the mean over all
>> cells or
>> > columns, you might want like this:
>> >
>> >
>> >
>> > myData <- vector("list", 3)
>> >
>> >
>> >
>> > for(i in 1:3){
>> >
>> >                 myData[[i]] <- matrix(rnorm(100), 10, 10)
>> >
>> >                 }
>> >
>> >
>> >
>> > ### mean over all cells
>> >
>> > sapply(myData, function(x) mean(x))
>> >
>> >
>> >
>> > ### mean over all columns
>> >
>> > sapply(myData, function(x) colMeans(x))
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > *From:* lily li [mailto:chocold12 at gmail.com]
>> > *Sent:* Tuesday, May 09, 2017 10:44 AM
>> > *To:* Doran, Harold <HDoran at air.org>
>> > *Cc:* R mailing list <r-help at r-project.org>
>> > *Subject:* Re: [R] About calculating average values from several
>> matrices
>>
>> >
>> >
>> >
>> > I'm trying to get a new dataframe or whatever to call, which has the
>> same
>> > structure with each file as listed above. For each cell in the new
>> > dataframe or the new file, it is the average value from former
>> dataframes
>> > at the same location. Thanks.
>> >
>> >
>> >
>> > On Tue, May 9, 2017 at 8:41 AM, Doran, Harold <HDoran at air.org> wrote:
>> >
>> > Are you trying to take the mean over all cells, or over rows/columns
>> > within each dataframe. Also, are these different dataframes stored
>> within a
>> > list or are they standalone?
>> >
>> >
>> >
>> >
>> > -----Original Message-----
>> > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of lily li
>> > Sent: Tuesday, May 09, 2017 10:39 AM
>> > To: R mailing list <r-help at r-project.org>
>> > Subject: [R] About calculating average values from several matrices
>> >
>> > Hi R users,
>> >
>> > I have a question about manipulating the data.
>> > For example, there are several such data frames or matrices, and I want
>> to
>> > calculate the average value from all the data frames or matrices. How
>> to do
>> > it? Also, should I convert them to data frame or matrix first? Right
>> now,
>> > when I use typeof() function, each one is a list.
>> >
>> > file1
>> >             jan   feb   mar   apr   may   jun   jul   aug   sep   oct
>>  nov
>> >
>> > app1   1.1   1.2    0.8    0.9   1.3    1.5   2.2   3.2   3.0    1.2
>>  1.1
>> > app2   3.1   3.2    2.8    2.5   2.3    2.5   3.2   3.0   2.9    1.8
>>  1.8
>> > app3   5.1   5.2    3.8    4.9   5.3    5.5   5.2   4.2   5.0    4.2
>>  4.1
>> >
>> > file2
>> >             jan   feb   mar   apr   may   jun   jul   aug   sep   oct
>>  nov
>> >
>> > app1   1.9   1.5    0.5    0.9   1.2    1.8   2.5   3.7   3.2    1.5
>>  1.6
>> > app2   3.5   3.7    2.3    2.2   2.5    2.0   3.6   3.2   2.8    1.2
>>  1.4
>> > app3   5.5   5.0    3.5    4.4   5.4    5.6   5.3   4.4   5.2    4.3
>>  4.2
>> >
>> > file3 has the similar structure and values...
>> >
>> > There are eight such files, and when I use the function mean(file1,
>> file2,
>> > file3, ..., file8), it returns the error below. Thanks for your help.
>> >
>> > Warning message:
>> > In mean.default(file1, file2, file3, file4, file5, file6, file7,  :
>> >   argument is not numeric or logical: returning NA
>> >
>> >         [[alternative HTML version deleted]]
>> >
>> > ______________________________________________
>> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> > https://stat.ethz.ch/mailman/listinfo/r-help
>> > PLEASE do read the posting guide http://www.R-project.org/
>> > posting-guide.html
>> > and provide commented, minimal, self-contained, reproducible code.
>> >
>> >
>> >
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posti
>> ng-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>

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