Question

我正在尝试更新一些代码。目前正在学习Python3，想知道是否可以用字典或元组更好地完成此工作？该代码查看一个csv文件并打印出值。我正在尝试更新代码，使其更简单，更可靠（如果可能）。

将样本数据用作：

品牌，型号，年份，颜色，引擎大小，最高速度，传输率
宝马，X6,2018，黑色，4L，240，手动

# use a sample piece of data as:
# brand,model,year,colour,engine_size,top_speed,transmission
# bmw,X6,2018,black,4L,240,manual

import csv

brand, model, year, colour, engine_size, top_speed, transmission = {}, 
{}, {}, {}, {}, {}, {}

counter = 0
with open("csv_test.csv", 'r') as csvFile:
    reader = csv.DictReader(csvFile)
    for row in reader:
        brand[counter] = row['brand']
        model[counter] = row['model']
        year[counter] = row['year']
        colour[counter] = row['colour']
        engine_size[counter] = row['engine_size']
        top_speed[counter] = row['top_speed']
        transmission[counter] = row['transmission']
        counter += 1
csvFile.close()

我知道DictReader将使用第一行作为列名，我想遍历每行并将值打印到屏幕上。

Answer 1

您不需要在每一列中使用一个字典：您只需在解析中使用list / dict中的row（每个 row 是一个字典）。这段代码将行存储在以“行号”为键的字典中（它从不使用此号码做任何事情-因此您可以简单地使用列表）。

创建演示数据：

# use a sample piece of data as:
with open("csv_test.csv","w") as f:
    f.write("""brand,model,year,colour,engine_size,top_speed,transmission
bmw,X6,2018,black,4L,240,manual
bmw,X7,2019,green,4L,240,manual
bmw,X8,2020,yellow,4L,240,manual
""")

加载/打印数据：

import csv

data = {}
with open("csv_test.csv", 'r') as csvFile:
    reader = csv.DictReader(csvFile)
    for num,row in enumerate(reader):  # num gives you the row number if you really need it
        data[num] = row  # put the line of your file into dict, row number is key

print(data)

# print data "nicely" 
for d in data:
    # get the maximum lenght for your keys to allow a nice formatting
    max_key = max(len(i) for k in data for i in data[k]) 
    for k in data[d]:
        # format the key to max length so data is aligned
        print(f"{k:{max_key}}\t{data[d][k]}")
    print()

输出：

# your parsed dict of row-dicts

{0: OrderedDict([('brand', 'bmw'), ('model', 'X6'), ('year', '2018'), ('colour', 'black'), 
                 ('engine_size', '4L'), ('top_speed', '240'), ('transmission', 'manual')]), 
 1: OrderedDict([('brand', 'bmw'), ('model', 'X7'), ('year', '2019'), ('colour', 'green'), 
                 ('engine_size', '4L'), ('top_speed', '240'), ('transmission', 'manual')]), 
 2: OrderedDict([('brand', 'bmw'), ('model', 'X8'), ('year', '2020'), ('colour', 'yellow'), 
                 ('engine_size', '4L'), ('top_speed', '240'), ('transmission', 'manual')])}

# the formatted output 
brand           bmw
model           X6
year            2018
colour          black
engine_size     4L
top_speed       240
transmission    manual

brand           bmw
model           X7
year            2019
colour          green
engine_size     4L
top_speed       240
transmission    manual

brand           bmw
model           X8
year            2020
colour          yellow
engine_size     4L
top_speed       240
transmission    manual

如果只想按行显示数据，请使用：

# print data in lines
for d in data:
    print(*data[d].values(), sep="\t")

输出：

bmw X6  2018    black   4L  240 manual
bmw X7  2019    green   4L  240 manual
bmw X8  2020    yellow  4L  240 manual

更新旧的Python代码-CSV读取和打印程序

1 个答案: