使用行名和列名将R数据帧转换为JSON

Question

Consider the following simple R data frame:

shape1 <- c('red','triangle')
shape2 <- c('blue','circle')
df <- data.frame(shape1,shape2)
rownames(df) <- c('Prop1','Prop2')

I would like to convert it to the following JSON:

{
"shape1": {"Prop1":"red","Prop2":"triangle"},
"shape2": {"Prop1":"blue","Prop2":"circle"}
}

Any ideas how to go about this?

Answer 1

In these situations it's sometimes easier to work backwards from the JSON and find out what R structure is required, to then give you back that JSON.

## start with the desired json
js <- '{"shape1": {"Prop1":"red","Prop2":"triangle"},
"shape2": {"Prop1":"blue","Prop2":"circle"}}'

## convert it into an R object (in this case, it's a list)
lst <- jsonlite::fromJSON(js)
lst
# $shape1
# $shape1$Prop1
# [1] "red"
# 
# $shape1$Prop2
# [1] "triangle"
# 
# 
# $shape2
# $shape2$Prop1
# [1] "blue"
# 
# $shape2$Prop2
# [1] "circle"

So now lst is the structure you require to get to your desired JSON

jsonlite::toJSON(lst, pretty = T)
# {
#   "shape1": {
#       "Prop1": ["red"],
#       "Prop2": ["triangle"]
#   },
#   "shape2": {
#       "Prop1": ["blue"],
#       "Prop2": ["circle"]
#   }
# }