how to use "for loop" and "write.csv" at the same time?

Question

I have an array. It has lat,lon,time,and value. Time starts from 1 to 300. Here is part of array for time=1.

myarray[,,1]
     lon                        
    lat -124.5  -123.5  -122.5  -121.5  -120.5  -119.5  -118.5
31.5    0   0   0   0   0   0
32.5    0   0   0   0   0   0
33.5    0   0   0   0   0   0
34.5    0   0   0   0   0   0
35.5    0   0   0   0   0   0
36.5    0   0   0   768.1   0   126.2
37.5    0   0   0.2 0   811 212.1
38.5    0   0   3055    0   243.9   243.7
39.5    0   0   1.5 0.1 3   0
40.5    0.1 16.8    4.3 0.5 2.1 0
41.5    0.2 398.6   0.4 1.2 1.6 0
42.5    0   0.1 0.9 0.1 0.7 0

I want to use "write.csv" and "for loop" at the same time to read the data from array for each time step (1 to 300) and store them in individual .csv files which has "i" as index. I used this command but it seems that it doesn't work:

for (i in 1:300)    write.csv(myarray[,,i],"myarray.i.csv")

Look at ?paste for how to construct a string where i is evaluated to the current value between 1 and 300 instead of just taken as the letter "i". — Frank
– Frank, Commented Oct 20, 2013 at 18:59

Paul Hiemstra · Accepted Answer · 2013-10-20 19:39:15Z

12

There are multiple ways of going about this:

paste('myarray', i, 'csv', sep = '.')

or:

sprintf('myarray.%d.csv', i)

I prefer the last one.

answered Oct 20, 2013 at 19:39

Paul Hiemstra

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1 Comment

TheComeOnMan Over a year ago

@PaulHiemestra, is sprintf preferred only because of the cleaner syntax or are there other reasons to it too?

seralouk · Accepted Answer · 2017-06-29 13:47:19Z

1

This should work fine:

n = dim(mydata)[3]

for(i in 1:n) {
  #unpack a 3D array
  mat = mydata[,,i]
  form = sprintf('subject_%s.csv', i)
  write.csv(mat, file = form)

}

answered Jun 29, 2017 at 13:47

seralouk

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Comments

MFR · Accepted Answer · 2016-04-05 01:00:18Z

0

One way is

for (i in 1:300)  {
write.table(myarray[,,i],file=""myarray.i.csv"",append=TRUE,sep=",",col.names=TRUE,row.names=TRUE) 
  }

answered Apr 5, 2016 at 1:00

MFR

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