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csv numpy python data-analysis genfromtxt

python - 如何通过列标题从csv中提取数据

发布于 2020-03-29 12:52:36

我有要分析和绘图的csv文件(制表符分隔)。我可以从文件中提取数据,但是我更愿意通过使用列标题名而不是常规索引来做到这一点。

即代替:

freq_data = my_data[:,0]

我会用类似的东西:

freq2_data=dataA['Freq']

这将只给我那一列数据,顶部字段不带“ nan”。如果某些人对数据的排序不同,我想这样做。

我目前拥有的是:

import os
import csv
import numpy as np
from numpy import genfromtxt

def mylistdir(directory):
    """A specialized version of os.listdir() that ignores files that
    start with a leading period."""
    filelist = os.listdir(directory)
    return [x for x in filelist
            if not (x.startswith('.'))]
path = ("C:\\Users\\priper\\Desktop\\rough_data\\")
results_files = mylistdir(path)
print(results_files)


vel_data = []

for f in results_files:
    f = path + f
    my_data = np.genfromtxt(f, dtype = float, delimiter='\t') #, names = True, max_rows=1
    print(my_data)
    freq_data = my_data[:,0]
    height_data = my_data[:,1]
    width_data = my_data[:,2]
    time_data = my_data[:,3]
    freq2_data=dataA['Freq']
    print(width_data)
    print(freq2_data)

关于我能做什么的任何想法?

csv文件:

Freqheight_cmsWidth_cmsTime_secs
"998.2121573301549  44.08897100772889   6.445672191528545   90.0"
"998.2121573301549  46.34952337794475   6.49171270718232    90.0"
"998.2121573301549  39.7907973252776    6.49171270718232    90.0"
"1999.404052443385  42.986804623146725  6.445672191528545   90.0"
"1999.404052443385  38.76177273904744   6.49171270718232    90.0"
"1999.404052443385  46.34952337794475   6.491875969369261   89.59365376669096"
"2997.61620977354   44.08897100772889   6.491875969369261   89.59365376669096"
"2997.61620977354   42.986804623146725  6.537915335317934   89.59651526494126"
"2997.61620977354   44.08897100772889   6.49171270718232    90.0"
"3998.80810488677   47.50820176059876   6.307550644567219   90.0"
"3998.80810488677   46.34952337794475   6.3535911602209945  90.0"
"3998.80810488677   41.903151251584184  6.3997972870975675  89.58780725859766"
"5000.0 38.76177273904744   6.21564013134898    89.57559458063852"
"5000.0 44.08897100772889   6.261510128913444   90.0"
"5000.0 41.903151251584184  6.2616793932272925  89.57871509583141"
"5998.212157330155  33.881963382336906  6.077522459688805   89.5659493678606"
"5998.212157330155  47.50820176059876   5.985444111277719   89.55927192723898"
"5998.212157330155  53.59203690324092   6.123388581952118   90.0"

这是仔细阅读以下用户给出的答案和提示后起作用的方法。

for f in results_files:
    f = path + f
    data = pd.read_csv(f, sep = '\t')
    length_of_data = len(data)
    print(data.head(length_of_data))
    freqy = data[['Freq']]
    print(freqy)

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提问者
Windy71
被浏览
97
Pablo Vilas 2020-01-31 16:32

使用 pandas 库:https : //pandas.pydata.org/pandas-docs/version/0.23.4/genic/pandas.read_csv.html

import pandas as pd

my_csv = pd.read_csv(filepath, header, names)

“标题:整数或整数列表,默认为'推断'

行号(用作列名)以及数据的开头。默认行为是推断列名:如果未传递名称,则行为与header = 0相同,并且从文件的第一行推断出列名;如果显式传递列名,则该行为与header = None相同。 。显式传递header = 0以便能够替换现有名称。标头可以是整数列表,这些整数指定列中多个索引的行位置,例如[0,1,3]。未指定的中间行将被跳过(例如,本示例中的2被跳过)。请注意,如果skip_blank_lines = True,则此参数将忽略注释行和空行,因此header = 0表示数据的第一行,而不是文件的第一行。

名称:类似数组,默认为无

要使用的列名列表。如果文件不包含标题行,则应显式传递header = None。此列表中的重复项将导致发出用户警告。”