convert dataframe to new list

Question

I have a data.frame NOAA_OLR_TEST

NOAA_OLR_TEST <- structure(list(DATE_START = structure(c(1170720000, 1170806400,
1170892800, 1170979200, 1171065600, 1171152         


        

Answer 1

You can do this with data.table:

library(data.table)
setDT(NOAA_OLR_TEST)
NOAA_OLR_TEST[,xy.list:=list(OLR_DATA_1,OLR_DATA_2,OLR_DATA_3,OLR_DATA_4,OLR_DATA_5)]
NOAA_OLR_TEST[,(5:9):= NULL]

is.list(NOAA_OLR_TEST$xy.list)
[1] TRUE

Answer 2

The question and subsequent comments by the OP are confusing what result the OP is expecting. So, I offer different variants:

Return a data.table with just columns 5:9

library(data.table)
NOAA_OLR_TEST_new <- setDT(NOAA_OLR_TEST)[, .SD, .SDcols = 5:9]
str(NOAA_OLR_TEST_new)

Classes ‘data.table’ and 'data.frame':    10 obs. of  5 variables:
 $ OLR_DATA_1: num  150 146 146 142 NA 150 158 155 143 142
 $ OLR_DATA_2: num  146 146 142 141 150 NA 155 143 142 138
 $ OLR_DATA_3: num  146 NA 141 150 158 155 143 142 138 135
 $ OLR_DATA_4: num  142 141 150 158 155 143 142 138 135 NA
 $ OLR_DATA_5: num  141 150 NA 155 143 142 138 135 140 139
 - attr(*, ".internal.selfref")=<externalptr>

Note that data.frames and data.tables are special forms of a list.

Return columns 5:9 as list

NOAA_OLR_TEST_new <- as.list(setDT(NOAA_OLR_TEST)[, .SD, .SDcols = 5:9])
str(NOAA_OLR_TEST_new)

List of 5
 $ OLR_DATA_1: num [1:10] 150 146 146 142 NA 150 158 155 143 142
 $ OLR_DATA_2: num [1:10] 146 146 142 141 150 NA 155 143 142 138
 $ OLR_DATA_3: num [1:10] 146 NA 141 150 158 155 143 142 138 135
 $ OLR_DATA_4: num [1:10] 142 141 150 158 155 143 142 138 135 NA
 $ OLR_DATA_5: num [1:10] 141 150 NA 155 143 142 138 135 140 139

Convert columns 5:9 as a list column of a data.table

NOAA_OLR_TEST_new <- setDT(NOAA_OLR_TEST)[, .(as.list(.SD)), .SDcols = 5:9]
str(NOAA_OLR_TEST_new)

Classes ‘data.table’ and 'data.frame':    5 obs. of  1 variable:
 $ V1:List of 5
  ..$ : num  150 146 146 142 NA 150 158 155 143 142
  ..$ : num  146 146 142 141 150 NA 155 143 142 138
  ..$ : num  146 NA 141 150 158 155 143 142 138 135
  ..$ : num  142 141 150 158 155 143 142 138 135 NA
  ..$ : num  141 150 NA 155 143 142 138 135 140 139
  ..- attr(*, ".data.table.locked")= logi TRUE
 - attr(*, ".internal.selfref")=<externalptr>

Answer 3

Just use c(...):

lst <- c(NOAA_OLR_TEST)[5:9];
#lst;
#List of 5
# $ OLR_DATA_1: num [1:10] 150 146 146 142 NA 150 158 155 143 142
# $ OLR_DATA_2: num [1:10] 146 146 142 141 150 NA 155 143 142 138
# $ OLR_DATA_3: num [1:10] 146 NA 141 150 158 155 143 142 138 135
# $ OLR_DATA_4: num [1:10] 142 141 150 158 155 143 142 138 135 NA
# $ OLR_DATA_5: num [1:10] 141 150 NA 155 143 142 138 135 140 139

Or with lapply:

lst <- lapply(5:9, function(i) NOAA_OLR_TEST[, i])