读取一个 csv 到一个跳过第一列的浮点数答案

【问题标题】：Read a csv to a float skipping the first column读取一个 csv 到一个跳过第一列的浮点数
【发布时间】：2021-04-30 17:00:48
【问题描述】：

S 我有一个 csv 文件，里面有一堆数据。当我尝试一些方法将整个事物转换为浮点数时，它给了我一个错误，说我无法将第一列中项目的内容更改为字符串（它实际上只是在它到达第一列后中断，所以我的假设是第一行的内容无法转换，这很好）。

我希望能够跳过第一列并将其余内容转换为浮点数。

当我读入我的 csv 文件时：

with open ('timecards.csv') as tcards:
    tcards = csv.reader(tcards)
    tfloat =[]
    for i in tcards:
        print(i)

我得到以下输出：

['51-4678119', '7.6', '3.1', '1.4', '4.1', '6.4', '7.7', '6.6']
['87-6664864', '5.2', '3.8', '7.5', '7.8', '7.0', '2.1', '3.6', '7.1', '5.1']
['07-3318962', '2.5', '6.9', '7.9', '7.7', '1.1', '2.6', '5.9', '6.1', '7.5', '3.6']
['06-4413296', '5.9', '4.2', '6.2', '3.1', '2.2', '7.6', '4.7', '6.7', '1.9', '7.4']
['58-5924013', '6.1', '6.2', '1.4', '3.2', '1.4', '1.2', '2.4', '4.4', '5.8', '2.2']
['45-9277595', '6.8', '1.6', '5.1', '3.2', '2.6', '7.1', '4.9', '1.6', '7.2', '2.8']
['04-0002399', '1.1', '6.2', '2.4', '3.8', '2.7', '7.0', '6.2', '2.3', '6.2', '4.3']
['27-7347997', '3.1', '2.1', '4.2', '3.7', '6.5', '7.0', '7.0', '3.9', '3.5', '4.6']
['38-0238479', '7.1', '2.1', '2.7', '6.8', '3.9', '2.6', '2.0', '1.5', '2.6', '1.3']

等等。我想让我的第一列保留一个我猜想的字符串，并将我的其余内容转换为浮点数。谢谢！

【问题讨论】：

标签： python string list csv

【解决方案1】：

这是使用map的一种方法

例如：

result =[]
with open ('timecards.csv') as tcards:
    tcards = csv.reader(tcards)
    for row in tcards:
        c1, *lst = row    # Column1 and rest of columns 
        result.append([c1] + list(map(float, lst)))

【讨论】：

【解决方案2】：

import csv
with open ('/tmp/timecards.csv') as tcards:
    for i in csv.reader(tcards):
        print([i[0]] + list(map(float, i[1:])))

结果：

['51-4678119', 7.6, 3.1, 1.4, 4.1, 6.4, 7.7, 6.6]
['87-6664864', 5.2, 3.8, 7.5, 7.8, 7.0, 2.1, 3.6, 7.1, 5.1]
['07-3318962', 2.5, 6.9, 7.9, 7.7, 1.1, 2.6, 5.9, 6.1, 7.5, 3.6]
['06-4413296', 5.9, 4.2, 6.2, 3.1, 2.2, 7.6, 4.7, 6.7, 1.9, 7.4]
['58-5924013', 6.1, 6.2, 1.4, 3.2, 1.4, 1.2, 2.4, 4.4, 5.8, 2.2]
['45-9277595', 6.8, 1.6, 5.1, 3.2, 2.6, 7.1, 4.9, 1.6, 7.2, 2.8]
['04-0002399', 1.1, 6.2, 2.4, 3.8, 2.7, 7.0, 6.2, 2.3, 6.2, 4.3]
['27-7347997', 3.1, 2.1, 4.2, 3.7, 6.5, 7.0, 7.0, 3.9, 3.5, 4.6]
['38-0238479', 7.1, 2.1, 2.7, 6.8, 3.9, 2.6, 2.0, 1.5, 2.6, 1.3]

【讨论】：

【解决方案3】：

>>> tcards = [['51-4678119', '7.6', '3.1', '1.4', '4.1', '6.4', '7.7', '6.6'],
              ['87-6664864', '5.2', '3.8', '7.5', '7.8', '7.0', '2.1', '3.6', '7.1', '5.1']]
>>> [[row[0]] + list(map(float, row[1:])) for row in tcards]
[['51-4678119', 7.6, 3.1, 1.4, 4.1, 6.4, 7.7, 6.6],
 ['87-6664864', 5.2, 3.8, 7.5, 7.8, 7.0, 2.1, 3.6, 7.1, 5.1]]
>>> # alternative (maybe simpler?)
>>> [[row[0]] + [float(val) for val in row[1:]] for row in tcards]
[['51-4678119', 7.6, 3.1, 1.4, 4.1, 6.4, 7.7, 6.6],
 ['87-6664864', 5.2, 3.8, 7.5, 7.8, 7.0, 2.1, 3.6, 7.1, 5.1]]

【讨论】：