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timestampapache-iotdb
leonbear
leonbear

Reputation: 196

How to convert the timestamp exported in csv form to string type in Apache IoTDB?

After exporting data csv from Apache IoTDB, are there any function that can convert the timestamp in the csv into a string type for time formatting? Since now in the table, my timestamp looks like to be a numeric form, I want to know how can I convert them to date format before I export them from IoTDB?

Upvotes: 0

Views: 153

Answers (3)

Summer
Summer

Reputation: 504

It depends on the unit of your TIME set in Apache IoTDB. For example, if your unit of time is ms in IoTDB, then you can execute from_unixtime(TIME/1000, 'yyyy-MM-dd HH:mm:ss') before exporting csv.

Upvotes: 1

Johnston Guan
Johnston Guan

Reputation: 1

In Java, you can use classes from the new date and time API in Java 8 and later to convert timestamps. To read and write CSVs, the Apache Commons CSV library can be used.

Here is a concise way to load a CSV file, convert the timestamps, and write the new CSV:

import org.apache.commons.csv.*;
import java.io.*;
import java.time.*;
import java.time.format.*;
import java.nio.file.*;

public class TimeConverter {
    public static void main(String[] args) throws IOException {
        Reader in = new FileReader("data.csv");
        Writer out = new FileWriter("formatted_data.csv");
        
        CSVFormat format = CSVFormat.DEFAULT.withFirstRecordAsHeader();
        CSVParser parser = new CSVParser(in, format);
        CSVPrinter printer = new CSVPrinter(out, format);
        
        parser.forEach(record -> {
            String strTimestamp = record.get("timestamp");
            long timestamp = Long.parseLong(strTimestamp);
            LocalDateTime dateTime =
                Instant.ofEpochMilli(timestamp).atZone(ZoneId.systemDefault()).toLocalDateTime();
            String formattedDateTime = dateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
            
            record = new CSVRecord(record.mapping(), record.values());
            record.replace("timestamp", formattedDateTime);
            printer.printRecord(record.toMap());
        });
        
        parser.close();
        printer.close();
    }
}

This script reads a CSV file "data.csv", converts the timestamps from the "timestamp" column, and writes the results to "formatted_data.csv". The timestamp is formatted as "Year-Month-Day Hour:Minute:Second". It uses the system's default time zone and expects timestamps in milliseconds since the Unix epoch.

Please replace "timestamp" with your actual column header name that carries the timestamp information. Make sure your CSV structure conforms with this expected format for the program to operate correctly. This is a basic program, enhancements may be necessary depending on your actual use case and specific requirements.

Upvotes: -1

Peter Lan
Peter Lan

Reputation: 1

There's no built-in function in Apache IoTDB to change the timestamp in numeric form to a date-time format during export. However, you can accomplish this task using programming languages like Python, Java, etc. after you export your data.

Here is a simple example for Python using pandas:

import pandas as pd

# load the data
df = pd.read_csv('your_file.csv')

# convert the 'timestamp' column to datetime
df['timestamp'] = pd.to_datetime(df['timestamp'], unit='ms')

# save the data
df.to_csv('your_file_converted.csv', index=False)

In this example, timestamp is the column with timestamps in your data. 'ms' is for milliseconds, change it as per your requirement.

Remember to adjust the code according to your usage including the file name and the timestamp column's name.

If you want to format the time (e.g, keep it up to seconds), you can use .dt.strftime function:

df['timestamp'] = pd.to_datetime(df['timestamp'], unit='ms').dt.strftime('%Y-%m-%d %H:%M:%S')

This will format your date in 'YYYY-MM-DD HH:MM:SS'. Please adjust according to your format.

Upvotes: -1

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