将列中观测值的NA值替换为特定字符串

import pandas as pd

# 读取数据
df = pd.read_csv("data.csv")

# 将NA值替换为特定字符串
df["column_name"].fillna("特定字符串", inplace=True)

# 输出结果
print(df)

# 读取数据
df <- read.csv("data.csv")

# 将NA值替换为特定字符串
df$column_name[is.na(df$column_name)] <- "特定字符串"

# 输出结果
print(df)

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.csv.CSVRecord;

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class CSVExample {
    public static void main(String[] args) throws IOException {
        // 读取数据
        CSVParser parser = new CSVParser(new FileReader("data.csv"), CSVFormat.DEFAULT.withHeader());

        // 创建输出文件
        CSVPrinter printer = new CSVPrinter(new FileWriter("output.csv"), CSVFormat.DEFAULT.withHeader(parser.getHeaderMap().keySet().toArray(new String[0])));

        // 遍历每一行数据
        for (CSVRecord record : parser) {
            // 将NA值替换为特定字符串
            String value = record.get("column_name");
            if (value == null || value.equals("NA")) {
                value = "特定字符串";
            }

            // 输出结果
            printer.printRecord(record.getRecordNumber(), value);
        }

        // 关闭文件
        parser.close();
        printer.close();
    }
}