R中的.csv数据操作而不是python

Question

我有一个简单的.csv格式数据,需要先进行操作才能创建符合此数据的绘图.但是,我理解如何从python中操作.csv格式数据.我想在R中应用相同的逻辑,但我不知道如何做到这一点.

下面是来自.csv文件的示例数据,但加载到R.我已经为我们创建了代码来讨论这个问题.

df <- data.frame(Name = c("AC", "AC", "PT", "PT", "OR", "OR"),
    useless_column = c("","","A",3,4," "),
  measurement = c("H", "", "K", "M", "", "H"),
  amount = c(12, 54, 20, 87, 75, 22),
    useless_column = c("","","A",3,4," ")) 

在python中,我通常会这样做:

import csv
import os
import glob
import sys
fileList = glob.glob("R:xxxxxxxxxxxxxxxxxxxxx\*.csv")
for inputFile in fileList:
        outputFilename = inputFile + "output.csv"
        csvInput = csv.reader(open(inputFile,'r'),delimiter=",")
        outputFile = open(outputFilename,'w')
        outputFile.write("Name,measurement,amount\n")
        csvInput.next()
        for line in csvInput:
            if line[2] == "H":
               meas = "100"
            elif line[2] == "K":
               meas = "1000"
            elif line[2] == "M":
               meas = "1000000"
            else:
               meas = "1"
            amount = int(meas) * line[3]

            outputFile.write(",".join(line[0],line[2],amount+"\n"]))
outputFile.close()

在python中,我可以加载csv然后使用for循环来识别csv文件中的每一行.然后在继续我的分析之前定制我的输出文件.从上面,我希望我的输出类似于下面的代码是R格式:

    df <- data.frame(Name = c("AC", "AC", "PT", "PT", "OR", "OR"),
  measurment = c("H", "", "K", "M", "", "H"),
  amount = c(1200, 54, 20000, 87000000, 75, 2200))

我想知道在R中这样做吗？我有一个小的R代码,任何人都可以引导我进入正确的方向:

x <- read.csv("xxxx.csv", header=T,sep=",")
xC = ncol(x)
xR = nrow(x)
op = data.frame(matrix(data = x, nrow= xR, ncol=3,byrow=T))
for (x in :xC)
{
    for (r in 1:xR)
    {
    xxxxxxxx

    }

Answer 1

在R中调整python代码意味着放弃循环以支持向量化操作.在这里,我们可以根据命名向量创建meas,然后计算金额:

# dictionnary of measurement values:
m <- c(H = 100, K = 1000, M = 1000000)

# create meas based on measurement
df$meas <- m[df$measurment]
df$meas[is.na(df$meas)] <- 1
# compute amount
df$amount <- df$meas * df$amount

数据

df <- data.frame(Name = c("AC", "AC", "PT", "PT", "OR", "OR"),
                 measurment = c("H", "", "K", "M", "", "H"),
                 amount = c(1200, 54, 20000, 87000000, 75, 2200))