Can fromJSON coerce type of variable?

[aamezqui]

I am scraping weather data from Wunderground, and found that jsonlite::fromJson incorrectly maps all temperature data (five variables, which are presented in the webpage with one decimal figure) as integers with (of course) zero decimals. The command recognises however other variables (e.g., rainfall, pressure, latitude) as doubles. Is there any general reason why jsonlite could incur in this wrong mapping? Is it possible define a priori the kind of data for each available "column" in a json file before importing it with fromJSON? I appreciate any help with this issue; I already invested a lot of time looking for possible solutions.

[jeroen]

Can you please include example code so we can see what you mean

[aamezqui]

Thanks Jeroen. The code is quite simple:

json2dfB <- function(id, date, key) {
u <- paste0("https://api.weather.com/v2/pws/history/all?stationId=",
id,
"&format=json&units=m&date=", date,
"&apiKey=", key)
u %>%
fromJSON() %>%
.$observations %>%
as_tibble() %>%
unnest(cols = c(metric))
}

wuDtTEST <- lapply("IJARDN7", function(x) json2dfB(x, "20230228", apikey)) %>%
bind_rows()

And a glimpse of the downloaded data; temperature should be dbl, as in other variables:
Rows: 288
Columns: 37
$ stationID "IJARDN7", "IJARDN7", "IJARDN7", "IJARDN7", "IJARDN7", "IJARDN7", "IJARD…
$ tz "America/Bogota", "America/Bogota", "America/Bogota", "America/Bogota", …
$ obsTimeUtc "2023-02-28T05:04:52Z", "2023-02-28T05:09:52Z", "2023-02-28T05:14:52Z", …
$ obsTimeLocal "2023-02-28 00:04:52", "2023-02-28 00:09:52", "2023-02-28 00:14:52", "20…
$ epoch 1677560692, 1677560992, 1677561292, 1677561592, 1677561892, 1677562192, …
$ lat 5.496274, 5.496274, 5.496274, 5.496274, 5.496274, 5.496274, 5.496274, 5.…
$ lon -75.887595, -75.887595, -75.887595, -75.887595, -75.887595, -75.887595, …
$ solarRadiationHigh 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, …
$ uvHigh 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, …
$ winddirAvg 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, …
$ humidityHigh 98, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 98, 98, 98, 99, 99, 99, 99, …
$ humidityLow 97, 97, 97, 97, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 98, 98, 98, 98, …
$ humidityAvg 97, 97, 97, 97, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 98, 98, 98, 98, …
$ qcStatus -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, …
$ tempHigh 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, …
$ tempLow 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, …
$ tempAvg 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, …

[jeroen]

I can't run this code (because I don't have your apikey), so it's hard for me to debug what is going wrong.

Perhaps you can help by further simplifying the example, and creating a small json blob that looks like your input, and then show what jsonlite is doing wrong when we parse it.