replace - how to change NA-s to empty cells in R -

i have data frame varying number of columns (depending on year have fewer or more data points). cross-sectional time series long dataset rather wide dataset need pull out vector each year (and create country tables).

at moment r puts nas @ end of rows if have fewer data points (which means of end columns have na-s).

however use each row input vector in python code not nas. replace nas empty cells. ideal have different length vectors. replacing nas zeros not work either since keep track of different row sizes different years. have found answers characters have numbers, appreciated. goal write table or csv file without na-s, pass each row in python code.
thank you!

 mat1 <- matrix(c(3,0, 1, 13, na, na,na, 3, 0, 1, 13,                    na, na, na, 3, 0 ,1 ,16, na, na, na,                   3,0, 1, 16, na, na, na, 0, 0, 134, 33, 39, 1, 14,                       0,0, 134, 33, 39, 1, 14),7,6) print(t(mat1))      [,1] [,2] [,3] [,4] [,5] [,6] [,7]  [1,]    3    0    1   13   na   na   na  [2,]    3    0    1   13   na   na   na  [3,]    3    0    1   16   na   na   na  [4,]    3    0    1   16   na   na   na  [5,]    0    0  134   33   39    1   14  [6,]    0    0  134   33   39    1   14 

as data.frame:

> print(as.data.frame(t(mat1)))  >    v1 v2 v3 v4 v5 v6 v7  > 1  3  0   1 13 na na na  > 2  3  0   1 13 na na na  > 3  3  0   1 16 na na na  > 4  3  0   1 16 na na na  > 5  0  0 134 33 39  1 14  > 6  0  0 134 33 39  1 14 

depending on how you're passing rows python code, there variety of ways of handling this, none of them correspond "emptying cells" - na value (arguably) best/most sensible way code empty cell in rectangular array in r.

 mat1 <- matrix(c(3,0, 1, 13, na, na,na, 3, 0, 1, 13,                na, na, na, 3, 0 ,1 ,16, na, na, na,               3,0, 1, 16, na, na, na, 0, 0, 134, 33, 39, 1, 14,                   0,0, 134, 33, 39, 1, 14),nrow=7,ncol=6)  mat2 <- t(mat1)  ## see below  ## text description says `na` values come @ end  ## of *rows*,  matrix has `na` values @ end of   ## *columns*, i've transposed matrix. 

since stated goal

write table or csv file without na-s

the correct answer (as hinted @ now-deleted comment) use write.csv(...,na=""): ?write.csv,

na: string use missing values in data.

more generally, if wanted pass rows python 1 @ time, use 1 of following strategies:

• use na.omit() strip out na values:

for (i in 1:nrow(mat2))     call_my_python_code(na.omit(mat2[i,])) 

or

apply(mat2,1,function(x) call_my_python_code(na.omit(x)) 

• store data list, either beginning or splitting list (you still have rid of na values):

my_list <- split(mat2,row(mat2)) my_list <- lapply(my_list,na.omit) lapply(my_list,call_my_python_code) 

• store data in long format , use plyr or dplyr tools operate on chunks ...

library(reshape2) mat3 <- na.omit(melt(mat2)) mat3[mat3$var1==1,]  ## row 1 library(plyr) dlply(mat3,"var1",function(x) call_my_python_code(x$value))