使用pandas或其他python模块读取特定列 [英] Read specific columns with pandas or other python module

问题描述

我有一个csv档案来自此网页。
我想读取下载文件中的某些列（csv版本可以在右上角下载）。

我想说的是2列：

• 59在标题中 star_name

，由于某种原因，网页的作者有时决定移动列。




最后，我想要这样的东西，记住值可能会丢失。

  data =以一种聪明的方式读取数据
 names = data ['star_name'] 
 ras = data ['ra'] 
  

这将防止我的程序在列再次更改





到目前为止，我已经尝试了使用 csv 模块的各种方法，重新使用 pandas 模块。没有任何运气。





EDIT（添加了两行+我的数据文件的标题，对不起，但非常长。）

 ＃名称，质量，mass_error_min，mass_error_max，半径，radius_error_min，radius_error_max，orbital_period，orbital_period_err_min，orbital_period_err_max，semi_major_axis，semi_major_axis_error_min，semi_major_axis_error_max，偏心，eccentricity_error_min，eccentricity_error_max，angular_distance，倾角，inclination_error_min，inclination_error_max，tzero_tr，tzero_tr_error_min，tzero_tr_error_max，tzero_tr_sec，tzero_tr_sec_error_min，tzero_tr_sec_error_max，lambda_angle，lambda_angle_error_min，lambda_angle_error_max，impact_parameter，impact_parameter_error_min，impact_parameter_error_max，tzero_vr，tzero_vr_error_min，tzero_vr_error_max，K，K_error_min，K_error_max，temp_calculated，temp_measured，hot_point_lon，反照率，albedo_error_min ，albedo_error_max，log_g，publication_status，发现更新，欧米茄，omega_error_min，omega_error_max，tperi，tperi_error_min，tperi_error_max，detection_type，mass_detection_type，radius_detection_type，alternate_names，分子，star_name，RA，DEC，mag_v，mag_i，mag_j，mag_h，mag_k，star_distance ，star_metallicity，star_mass，star_radius，star_sp_type，star_age，star_teff，star_detected_disc，star_magnetic_field 
 11的COM b，19.4,1.5,1.5 ,,,, 326.03,0.32,0.32,1.29,0.05,0.05,0.231,0.005,0.005 ，0.011664 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1,2008,2011-12-23,94.8,1.5,1.5,2452899.6,1.6 ，1.6，径向速度,,,, 11 Com，185.1791667,17.7927778,4.74 ,,,, 110.6，-0.35,2.7,19​​.0，G8 III ,, 4742.0 ,, 
 11 UMi b，10.5,2.47 ，2.47 ,,,, 516.22,3.25,3.25,1.54,0.07,0.07,0.08,0.03,0.03,0.012887 ,,,,,,,,,,,,,,,,,,, ,,,, 1,2009,2009-08-13,117.63,21.06,21.06,2452861.05,2.06,2.06，径向速度,,,,, 11 UMI，229.275,71.8238889,5.02 ,,,,, 119.5,0.04,1.8， 24.08，K4III，1.56,4340.0 ,, 
  




解决方案

方法是使用 pandas 库。

  import大熊猫作为PD 
栏= ['star_name'，'岭'] 
 
 DF = pd.read_csv（'data.csv'，skipinitialspace = TRUE，usecols =字段）
 ＃See the keys 
 print df.keys（）
＃查看'star_name'中的内容
 print df.star_name 
  

这里的问题是 skipinitialspace ，它删除了标题中的空格。因此，star_name变成了star_name




I have a csv file from this webpage. I want to read some of the columns in the downloaded file (the csv version can be downloaded in the upper right corner).

Let's say I want 2 columns:

• 59 which in the header is star_name
• 60 which in the header is ra.

However, for some reason the authors of the webpage sometimes decide to move the columns around.

In the end I want something like this, keeping in mind that values can be missing.

data = #read data in a clever way
names = data['star_name']
ras = data['ra']

This will prevent my program to malfunction when the columns are changed again in the future, if they keep the name correct.

Until now I have tried various ways using the csv module and resently the pandas module. Both without any luck.

EDIT (added two lines + the header of my datafile. Sorry, but it's extremely long.)

# name, mass, mass_error_min, mass_error_max, radius, radius_error_min, radius_error_max, orbital_period, orbital_period_err_min, orbital_period_err_max, semi_major_axis, semi_major_axis_error_min, semi_major_axis_error_max, eccentricity, eccentricity_error_min, eccentricity_error_max, angular_distance, inclination, inclination_error_min, inclination_error_max, tzero_tr, tzero_tr_error_min, tzero_tr_error_max, tzero_tr_sec, tzero_tr_sec_error_min, tzero_tr_sec_error_max, lambda_angle, lambda_angle_error_min, lambda_angle_error_max, impact_parameter, impact_parameter_error_min, impact_parameter_error_max, tzero_vr, tzero_vr_error_min, tzero_vr_error_max, K, K_error_min, K_error_max, temp_calculated, temp_measured, hot_point_lon, albedo, albedo_error_min, albedo_error_max, log_g, publication_status, discovered, updated, omega, omega_error_min, omega_error_max, tperi, tperi_error_min, tperi_error_max, detection_type, mass_detection_type, radius_detection_type, alternate_names, molecules, star_name, ra, dec, mag_v, mag_i, mag_j, mag_h, mag_k, star_distance, star_metallicity, star_mass, star_radius, star_sp_type, star_age, star_teff, star_detected_disc, star_magnetic_field
11 Com b,19.4,1.5,1.5,,,,326.03,0.32,0.32,1.29,0.05,0.05,0.231,0.005,0.005,0.011664,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,2008,2011-12-23,94.8,1.5,1.5,2452899.6,1.6,1.6,Radial Velocity,,,,,11 Com,185.1791667,17.7927778,4.74,,,,,110.6,-0.35,2.7,19.0,G8 III,,4742.0,,
11 UMi b,10.5,2.47,2.47,,,,516.22,3.25,3.25,1.54,0.07,0.07,0.08,0.03,0.03,0.012887,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,2009,2009-08-13,117.63,21.06,21.06,2452861.05,2.06,2.06,Radial Velocity,,,,,11 UMi,229.275,71.8238889,5.02,,,,,119.5,0.04,1.8,24.08,K4III,1.56,4340.0,,

解决方案

An easy way to do this is using the pandas library like this.

import pandas as pd
fields = ['star_name', 'ra']

df = pd.read_csv('data.csv', skipinitialspace=True, usecols=fields)
# See the keys
print df.keys()
# See content in 'star_name'
print df.star_name

The problem here was the skipinitialspace which remove the spaces in the header. So ' star_name' becomes 'star_name'

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