Key error & Pandas

问题

I wrote a Python script (below) which load data from a text file (using pandas) and checks the values in the columns.

import sys
import pandas as pd
import numpy as np
from numpy import ndarray
import math
import matplotlib.pyplot as plt
from matplotlib.pyplot import *
from skimage import data
from skimage.feature import match_template

if __name__ == '__main__':
    data = pd.read_csv('Fe_PSI_spt_refined.txt', sep=" ", header = None)
    data.columns = ["Angle_number", "Omega", "Intensity", "X", "Y", "Address", "ID"]#, "flag"]
    Number_of_projections = 181
    Number_of_lines_in_txt = 3493
    numrows = len(data)
    counter_array = []
    correlation_threshold_value = 0.7
    a = np.zeros(Number_of_lines_in_txt)
    output_file = ("output.txt")

    for i in range(2, (Number_of_projections + 1)): 
        filename_cutouts_combined = ("cutouts_combined_%03i.txt" % (i))
        filename_cutouts_combined_tag = ("cutouts_combined_tag_%03i.txt" % (i))
        image = np.loadtxt(filename_cutouts_combined)
        image_tagged = np.loadtxt(filename_cutouts_combined_tag)
        for j in range(0, Number_of_lines_in_txt - 1):
            print data.Angle_number[j], i

After one iteration of j I get the error below. Do you spot any error I should fix? Thanks

`Traceback (most recent call last):
  File "Hyperbola_search.py", line 46, in <module>
    print data.Angle_number[j], i
  File "/Users/Alberto/anaconda/lib/python2.7/site-packages/pandas/core/series.py", line 491, in __getitem__
    result = self.index.get_value(self, key)
  File "/Users/Alberto/anaconda/lib/python2.7/site-packages/pandas/core/index.py", line 1032, in get_value
    return self._engine.get_value(s, k)
  File "index.pyx", line 97, in pandas.index.IndexEngine.get_value (pandas/index.c:2661)
  File "index.pyx", line 105, in pandas.index.IndexEngine.get_value (pandas/index.c:2476)
  File "index.pyx", line 149, in pandas.index.IndexEngine.get_loc (pandas/index.c:3215)
  File "hashtable.pyx", line 382, in pandas.hashtable.Int64HashTable.get_item (pandas/hashtable.c:6450)
  File "hashtable.pyx", line 388, in pandas.hashtable.Int64HashTable.get_item (pandas/hashtable.c:6394)
KeyError: 3491`

回答1:

You load files into image and image_tagged, while a remains unused.

I don't know what data.Angle_number and numrows are, but they appear to be from libraries, not related to your files.

来源：https://stackoverflow.com/questions/22665758/key-error-pandas