Wrong exception thrown for empty dataframe

Using the get started query example https://danfo.jsdata.org/api-reference/dataframe/danfo.dataframe.query

let data = {"A": [30, 1, 2, 3],
           "B": [34, 4, 5, 6],
           "C": [20, 20, 30, 40]}
           
let cols = ["A", "B", "C"]
let df = new dfd.DataFrame(data, { columns: cols })
df.print() //before query

let query_df = df.query({ "column": "B", "is": ">", "to": 5 })
table(query_df)

I modified the condition to

let data = {"A": [30, 1, 2, 3],
           "B": [34, 4, 5, 6],
           "C": [20, 20, 30, 40]}
           
let cols = ["A", "B", "C"]
let df = new dfd.DataFrame(data, { columns: cols })
df.print() //before query

let query_df = df.query({ "column": "B", "is": ">", "to": 40 })
table(query_df)

Error message

File format not supported for now

Expected Output: Return empty result/array

[iGorjidooz]

Hi everyone! When I am querying a DataFrame which would return an empty result, danfojs-node throws the following error (as it is implemented in core/frame.js) Error: query returned empty data but shouldn’t it actually return an empty DataFrame like in Pandas? IMO, throwing an error breaks the chain of execution and it would make it difficult in cases where a decision is dependent on the query to return empty result or not.

[risenW]

This has been fixed in the latest conversion to TS. See #235