Question

我正在 Python 中制作一个小的食谱输入和输出程序，但是我在将成分写入 CSV 文件时遇到了麻烦。我正在尝试使用以下代码将列表中的每个项目打印到逗号分隔文件：

with open('recipes/' + recipeName + '.csv', 'w') as csvfile:
    recipewriter = csv.writer(csvfile)
    recipewriter.write(ingredientList[0])
    recipewriter.write(ingredientList[1])
    recipewriter.write(ingredientList[2])

在列表中，有三个项目。例如，这可能是我试图保存到文件的列表：

ingredientList = ['flour', '500', 'g']

我希望数据在CSV文件中显示如下：

flour,
500,
g,

相反，它看起来像这样：

f,l,o,u,r,
5,0,0,
g,

如何让它以我想要的格式显示？

这是我的源代码：

#Python 3.3.3

import sys #Allows use of the 'exit()' function
import csv #Allows use of the CSV File API

def mainMenu():
    print("########################################################")
    print("# Welcome to the recipe book, please select an option: #")
    print("# 1. Add new recipe                                    #")
    print("# 2. Lookup existing recipe                            #")
    print("# 3. Exit                                              #")
    print("########################################################")

    selectedOption = None
    inputtedOption = input()

    try:
        inputtedOption = int(inputtedOption)
    except ValueError:
        print("Invalid option entered")

    if inputtedOption == 1:
        selectedOption = inputtedOption
    elif inputtedOption == 2:
        selectedOption = inputtedOption
    elif inputtedOption == 3:
        print("Exiting...")
        sys.exit(0)

    return selectedOption

def validateInput(inputtedData):
    try: #Test if data is an integer greater than 1
        inputtedData = int(inputtedData)
        if int(inputtedData) < 1: #Recipes cannot contain less than 1 ingredient
            print("Sorry, invalid data entered.\n('%s' is not valid for this value - positive integers only)" % inputtedData)
            return False
        return int(inputtedData)
    except ValueError:
        print("Sorry, invalid data entered.\n('%s' is not valid for this value - whole integers only [ValueError])\n" % inputtedData)
        return False

def addRecipe():
    print("Welcome to recipe creator! The following questions will guide you through the recipe creation process.\nPlease enter the name of your recipe (e.g. 'Pizza'):")
    recipeName = input()
    print("Recipe Name: %s" % recipeName)
    print("Please enter the amount of people this recipe serves (e.g. '6'):")
    recipeServingAmount = input()
    if validateInput(recipeServingAmount) == False:
        return
    else:
        recipeServingAmount = validateInput(recipeServingAmount)
    print("Recipe serves: %s" % recipeServingAmount)
    print("Please enter the number of ingredients in this recipe (e.g. '10'):")
    recipeNumberOfIngredients = input()
    if validateInput(recipeNumberOfIngredients) == False:
        return
    else:
        recipeNumberOfIngredients = validateInput(recipeNumberOfIngredients)
    print("Recipe contains: %s different ingredients" % recipeNumberOfIngredients)
    ingredientList = {}
    i = 1
    while i <= recipeNumberOfIngredients:
        nthFormat = "st"
        if i == 2:
            nthFormat = "nd"
        elif i == 3:
            nthFormat = "rd"
        elif i >= 4:
            nthFormat = "th"
        ingredientNumber = str(i) + nthFormat
        print("Please enter the name of the %s ingredient:" % ingredientNumber)
        ingredientName = input()
        print("Please enter the quantity of the %s ingredient:" % ingredientNumber)
        ingredientQuantity = input()
        print("Please enter the measurement value for the %s ingredient (leave blank for no measurement - e.g. eggs):"  % ingredientNumber)
        ingredientMeasurement = input()
        print("%s ingredient: %s%s %s" % (ingredientNumber, ingredientQuantity, ingredientMeasurement, ingredientName))
        finalIngredient = [ingredientName, ingredientQuantity, ingredientMeasurement]
        print(finalIngredient[1])
        ingredientList[i] = finalIngredient
        with open('recipes/' + recipeName + '.csv', 'w') as csvfile:
            recipewriter = csv.writer(csvfile)
            recipewriter.write(ingredientList[0])
            recipewriter.write(ingredientList[1])
            recipewriter.write(ingredientList[2])

        i = i + 1

def lookupRecipe():
    pass  # To-do: add CSV reader and string formatter

#Main flow of program
while True:
    option = mainMenu()

    if option == 1:
        addRecipe()
    elif option == 2:
        lookupRecipe()

Answer 1

csv.writer没有write()方法。在Python 3中你可以这样做：

with open('recipes/' + recipeName + '.csv', 'w', newline='') as csvfile:
    recipewriter = csv.writer(csvfile)
    recipewriter.writerow([ingredientList[0]])
    recipewriter.writerow([ingredientList[1]])
    recipewriter.writerow([ingredientList[2]])

Answer 2

最简单的方法是在列表中调用join，添加,和换行符，忘记使用csv模块：

with open('recipes/{}.csv'.format(recipeName), 'w') as csvfile:
        csvfile.write(",\n".join(ingredientList))

输出：

flour,
500,
g

我认为你实际上在使用writerow而不是写csv.writer没有写方法。

您看到f,l,o,u,r,的原因是因为csv.writer.writerow期望迭代，所以当您传递字符串时，它会迭代并单独写入每个字符。

您需要使用recipewriter.writerow([ingredientList[0]])，将字符串包装在列表中。

在字符串结束后，实际上仍然不会添加任何尾随逗号。

如果你想在每行后面都有一个逗号，包括最后一行：

with open('recipes/{}.csv'.format("foo"), 'w') as csvfile:
    for ele in ingredientList:
         csvfile.write("{},\n".format(ele))

输出：

flour,
500,
g,

如果你想要一个有用的csv，你可能会更好地制作每个自己的专栏，或者只是将它们写成自己的专栏：

import csv
with open('{}.csv'.format("foo"), 'w') as csvfile:
    recipewriter = csv.writer(csvfile)
    recipewriter.writerow(ingredientList)

输出：

flour,500,g

或在没有逗号的单行上：

with open('{}.csv'.format("foo"), 'w') as csvfile:
    recipewriter = csv.writer(csvfile)
    for ele in ingredientList:
         recipewriter.writerow([ele])

输出：

flour
500
g

如何在各行和列上正确写入CSV文件？

2 个答案: