I would like to convert an xts object which has the class Date into JSON with jsonlite::toJSON but it returns an error saying No method asJSON S3 class: zoo.
My objective is to have a JSON file that can be handled by highcharts.js library, so I'm trying to have severals arrays [unixtime, value], something like this :
[[1489363200, -0.01766174], [1489968000, 0.00000021], [1490572800, 0.00000098]]
This is my xts object :
> obj
values
2017-03-13 -0.01766174
2017-03-20 0.00000021
2017-03-27 0.00000098
The documentation of toJSON mention a Date option that is used
to encode Date objects: must be one of 'ISO8601' or 'epoch', but for some reason there is the same error.
> data <- toJSON(obj, dataframe = "values", Date="epoch")
Error: No method asJSON S3 class: zoo
If I convert the xts into a dataframe or a matrix I can export in JSON but the format is no appropriate for highcharts.js :
[-0.0177,"2017-03-13"],[0,"2017-03-20"],[0,"2017-03-27"]]
Is there a possibility to export an xts object in a JSON by keeping the time serie ?
Thank you,
One way to do it would be do it manually. The main steps are:
datetime_to_timestamp from the highcharter package.
library(xts)
library(highcharter)
library(jsonlite)
data(sample_matrix)
obj <- as.xts(head(sample_matrix[, 1], 3), descr = "my new xts object")
obj
#> [,1]
#> 2007-01-02 50.03978
#> 2007-01-03 50.23050
#> 2007-01-04 50.42096
df <- data.frame(time = time(obj), values = as.vector(obj))
df
#> time values
#> 1 2007-01-02 50.03978
#> 2 2007-01-03 50.23050
#> 3 2007-01-04 50.42096
df$time <- datetime_to_timestamp(df$time)
df
#> time values
#> 1 1.167707e+12 50.03978
#> 2 1.167793e+12 50.23050
#> 3 1.167880e+12 50.42096
toJSON(as.matrix(df))
#> [[1167706800000,50.0398],[1167793200000,50.2305],[1167879600000,50.421]]