Reading date in csv as string instead of datetime

[iserranoe]

I'm reading a csv file into a data frame. One of the columns is a date and Danfo is automatically reading and transforming it into datetime format; however I'd like to mantain the date as a string, how can I do it?

[risenW]

Hello @iserranoe Danfojs does not automatically parse dates. It only tries to parse date strings when you call the .dt method on the column. See https://danfo.jsdata.org/api-reference/general-functions/danfo.dt

[iserranoe]

Hi @risenW, I've just came back to this problem. Let me show you more information, as I find Danfojs is parsing dates somehow.

I have a .csv file with this data:

,result,table,_measurement,_time,days,pH,total_hours
,_result,0,57b6,2022-06-27T14:39:55Z,0.003,14,0.076
,_result,0,57b6,2022-06-27T14:45:07Z,0.006,14,0.163
,_result,0,57b6,2022-06-27T14:50:19Z,0.010,14,0.249
,_result,0,57b6,2022-06-27T14:55:31Z,0.014,14,0.336
,_result,0,57b6,2022-06-27T15:00:43Z,0.017,14,0.423

I then read the csv file with dfd.readCSV and can see the dates are transformed:

>const dfd = require("danfojs-node")
>dfd.readCSV('./data.csv').then(df=>{df.print(); df.column('_time').print()}).catch(e=>{console.log(e)})

The output is:

 >dfd.readCSV('./data.csv').then(df=>{df.print(); df.ctypes.print(); df.column('_time').print()}).catch(e=>{console.log(e)})
Promise {
  <pending>,
  [Symbol(async_id_symbol)]: 1036,
  [Symbol(trigger_async_id_symbol)]: 1035,
  [Symbol(destroyed)]: { destroyed: false }
}
> ╔════════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║            │                   │ result            │ table             │ _measurement      │ _time             │ days              │ pH                │ total_hours       ║
╟────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 0          │ null              │ _result           │ 0                 │ 57b6              │ Mon Jun 27 2022…  │ 0.003             │ 14                │ 0.076             ║
╟────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 1          │ null              │ _result           │ 0                 │ 57b6              │ Mon Jun 27 2022…  │ 0.006             │ 14                │ 0.163             ║
╟────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 2          │ null              │ _result           │ 0                 │ 57b6              │ Mon Jun 27 2022…  │ 0.01              │ 14                │ 0.249             ║
╟────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 3          │ null              │ _result           │ 0                 │ 57b6              │ Mon Jun 27 2022…  │ 0.014             │ 14                │ 0.336             ║
╟────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 4          │ null              │ _result           │ 0                 │ 57b6              │ Mon Jun 27 2022…  │ 0.017             │ 14                │ 0.423             ║
╚════════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝

╔══════════════╤═════════╗
║              │ float32 ║
╟──────────────┼─────────╢
║ result       │ string  ║
╟──────────────┼─────────╢
║ table        │ int32   ║
╟──────────────┼─────────╢
║ _measurement │ string  ║
╟──────────────┼─────────╢
║ _time        │ int32   ║
╟──────────────┼─────────╢
║ days         │ float32 ║
╟──────────────┼─────────╢
║ pH           │ int32   ║
╟──────────────┼─────────╢
║ total_hours  │ float32 ║
╚══════════════╧═════════╝

Error: File format not supported!
    at Series.NDframe (/home/ines/ofelia/frontend/node_modules/danfojs-node/dist/danfojs-base/core/generic.js:97:23)
    at new Series (/home/ines/ofelia/frontend/node_modules/danfojs-node/dist/danfojs-base/core/series.js:134:28)
    at DataFrame.$getColumnData (/home/ines/ofelia/frontend/node_modules/danfojs-node/dist/danfojs-base/core/frame.js:196:24)
    at DataFrame.column (/home/ines/ofelia/frontend/node_modules/danfojs-node/dist/danfojs-base/core/frame.js:1939:21)
    at REPL90:1:52
    at processTicksAndRejections (node:internal/process/task_queues:96:5)

So, the dates are transformed from 2022-06-27T14:39:55Z format to Mon Jun 27 2022… format and I can't access the column dt.column('_time'). I'd like them to keep the original format, i.e. 2022-06-27T14:39:55Z, as a string instead of converting to datetime format.