使用AWK过滤和计算CSV文件

这个示例代码演示了如何使用AWK工具对CSV文件进行过滤和计算，它通过读取输入文件，查找匹配的行并对其中的数据执行计算，并输出结果到终端。其实现方式利用了AWK内置的语言特性和命令选项。

#!/usr/bin/awk -f
# usage example: awk -f csv.awk -v col=2 -v val=10 -v op=sum input.csv

# parse command line options
BEGIN {
  if (ARGC < 5) {
    print "Usage: awk -f csv.awk -v col=<column> -v val=<value> -v op=<operation> <input.csv>"
    exit 1
  }
  col = ARGV[2]
  val = ARGV[4]
  op = ARGV[6]
  delete ARGV[1]; delete ARGV[2]; delete ARGV[3]; delete ARGV[4]; delete ARGV[5]; delete ARGV[6]
}

# process input file
NR == 1 {
  # process header
  split($0, headers, ",")
  for (i = 1; i <= length(headers); i++) {
    if (headers[i] == col) {
      col_index = i
      break
    }
  }
} 
NR > 1 {
  # process rows
  split($0, row, ",")
  if (row[col_index] == val) {
    if (op == "sum") {
      sum += row[col_index+1]
    }
    else if (op == "avg") {
      sum += row[col_index+1]
      count += 1
    }
    else if (op == "max" && row[col_index+1] > max) {
      max = row[col_index+1]
    }
    else if (op == "min" && row[col_index+1] < min) {
      min = row[col_index+1]
    }
  }
}

# print results
END {
  if (op == "sum") {
    print sum
  }
  else if (op == "avg") {
    print sum / count
  }
  else if (op == "max") {
    print max
  }
  else if (op == "min") {
    print min
  }
}

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