Hi R-users, I have a csv file that contains weather observation (rows) by days (in columns). I open using:> temp = read.csv("Weather.csv", sep=",")and read: X X1.Jan X2.Jan X3.Jan X4.Jan 1 Min 2 3 4 1 2 Max 6 10 8 6 3 Forecast Min 3 1 1 3 4 Forecast Max 8 7 4 9 If I type mean(temp[2,2:3]) I get X1.Jan X2.Jan 6 10 The same command on> y = matrix(1:21, ncol=7)> mean(y[2,2:3])[1] 6.5 Works because the data is in a matrix. I believe R stores the data from the csv file as a data.frame with these annoying headers. So how do I convert the data from my csv file into a matrix? I tried as.matrix but it did not help. Many many thanks! -- View this message in context: http://r.789695.n4.nabble.com/Read-data-from-csv-file-as-a-matrix-tp2131546p2131546.html Sent from the R help mailing list archive at Nabble.com.
Hello,> I have a csv file that contains weather observation (rows) by days (in > columns). > > I open using: > >> temp = read.csv("Weather.csv", sep=",") > > and read: > > X X1.Jan X2.Jan X3.Jan X4.Jan > 1 Min 2 3 4 1 > 2 Max 6 10 8 6 > 3 Forecast Min 3 1 1 3 > 4 Forecast Max 8 7 4 9 > > If I type > > mean(temp[2,2:3]) > > I get > > X1.Jan X2.Jan > 6 10 > > The same command on > >> y = matrix(1:21, ncol=7) > >> mean(y[2,2:3]) > [1] 6.5 > > Works because the data is in a matrix. I believe R stores the data from the > csv file as a data.frame with these annoying headers. So how do I convert > the data from my csv file into a matrix? > > I tried as.matrix but it did not help. >Giving us a reproducible example with ?dput output from your temp object would most likely help us solve the problem very quickly.
> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- > project.org] On Behalf Of vincent.deluard > Sent: Wednesday, May 05, 2010 12:34 PM > To: r-help at r-project.org > Subject: [R] Read data from .csv file as a matrix > > > Hi R-users, > > > I have a csv file that contains weather observation (rows) by days (in > columns). > > I open using: > > > temp = read.csv("Weather.csv", sep=",") > > and read: > > X X1.Jan X2.Jan X3.Jan X4.Jan > 1 Min 2 3 4 1 > 2 Max 6 10 8 6 > 3 Forecast Min 3 1 1 3 > 4 Forecast Max 8 7 4 9 > > If I type > > mean(temp[2,2:3]) > > I get > > X1.Jan X2.Jan > 6 10 > > The same command on > > > y = matrix(1:21, ncol=7) > > > mean(y[2,2:3]) > [1] 6.5 > > Works because the data is in a matrix. I believe R stores the data from > the > csv file as a data.frame with these annoying headers. So how do I > convert > the data from my csv file into a matrix? > > I tried as.matrix but it did not help. > > > Many many thanks!I'm only guessing because you haven't given us much to go on, but maybe something like mean(unlist(temp[2,2:3])) Hope this is helpful, Dan Daniel J. Nordlund Washington State Department of Social and Health Services Planning, Performance, and Accountability Research and Data Analysis Division Olympia, WA 98504-5204
Vincent,
The root of this problem seems to be that you don't fully understand the
differences between matrix and data.frame.? Read up on them and you'll know
how to solve this problem.
For now:
as.matrix(temp[,-1])
or
temp = read.csv("Weather.csv", sep=",", row.names=1)
temp1 <- as.matrix(temp)
should work.
...Tao
> I have a csv file that contains weather observation (rows) by days (in
> columns).
>
> I open using:
>
>> temp = read.csv("Weather.csv", sep=",")
>
> and read:
>
> X X1.Jan X2.Jan X3.Jan X4.Jan
> 1 Min 2 3 4 1
> 2 Max 6 10 8 6
> 3 Forecast Min 3 1 1 3
> 4 Forecast Max 8 7 4 9
>
> If I type
>
> mean(temp[2,2:3])
>
> I get
>
> X1.Jan X2.Jan
> 6 10
>
> The same command on
>
>> y = matrix(1:21, ncol=7)
>
>> mean(y[2,2:3])
> [1] 6.5
>
> Works because the data is in a matrix. I believe R stores the data from the
> csv file as a data.frame with these annoying headers. So how do I convert
> the data from my csv file into a matrix?
>
> I tried as.matrix but it did not help.
>
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