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rdataframenumericrjson

Convert character list to data frame

I have some data in JSON I am trying to use in R. My problem is I cannot get the data in the right format. 

require(RJSONIO)

json <- "[{\"ID\":\"id1\",\"VALUE\":\"15\"},{\"ID\":\"id2\",\"VALUE\":\"10\"}]"
example <- fromJSON(json)

example <- do.call(rbind,example)
example <- as.data.frame(example,stringsAsFactors=FALSE)

> example
   ID VALUE
1 id1    15
2 id2    10

This gets close, but I cannot get the numeric column to convert to numeric. I know I can convert columns manually, but I thought data.frame or as.data.frame scanned the data and made the most appropriate class definitions. Clearly I misunderstood. I am reading in numerous tables - all very different - and I need to have the numeric data treated as such when it's numeric.

Ultimately I am looking to get data tables with numeric columns when the data is numeric.

Solution

  • read.table uses type.convert to convert data to the appropriate type. You could do the same as a cleaning step after reading in the JSON data.

    sapply(example,class)
         # ID       VALUE 
# "character" "character" 
example[] <- lapply(example, type.convert, as.is = TRUE)
sapply(example, class)
         # ID       VALUE 
# "character"   "integer"