Python数组形状的索引太多（0，）

Question

again continue from my previous work, I have manage to loop through the list into function but I am not able to plot the way I run the loop on a list

%matplotlib inline
from pylab import *
import numpy as np

with open('/home/../Downloads/combinationplot.txt','rb') as file:
    a = file.readlines()


df = pd.read_csv('20130831_000000.csv')
df = df.fillna(0)

def createtuple(cola,colb):
    names = df[str(cola)]
    names1 = df[str(colb)]
    X = []
    y = []
    for i in range(len(names)):
        if type(names[i])==str or type(names1[i])==str :
            pass
        else:
            X.append([names[i],names1[i]])
            y.append(i+1)

    X = np.array(X)
    y = np.array(y)
    return (X,y)

def plotgraph():
    plt.figure(figsize=(10, 6))
    plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5)
    #plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5) names[i] <=float(0) or names1[i]<=float(0) or 
    plt.show()

for i in range(len(a)):
    b = a[i].split("'")
    (X,y) = createtuple(b[1],b[3])
    print (X,y)
    print np.shape(X)

    plt.figure(figsize=(10, 6))

    plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5)
    #plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5) names[i] <=float(0) or names1[i]<=float(0) or 
    plt.show()

The error I am seeing is this:

(0,)
(array([], dtype=float64), array([], dtype=float64))
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-109-1875f2993e46> in <module>()
     39     plt.figure(figsize=(10, 6))
     40 
---> 41     plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5)
     42     #plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5) names[i] <=float(0) or names1[i]<=float(0) or
     43     plt.show()

IndexError: too many indices for array

<matplotlib.figure.Figure at 0x7f46edb9b9d0>
In [ ]:

I know the tuple in the list is being called X[:,0], X[:,1] but what does it mean of getting (0,) for shape of X?

Answer 1

You're trying to reference at second dimension X[:, 0] on X when you specified it is a one dimensional array. Your loop will make X 2-dim only if it passes into the else clause. If it doesn't, it will remain 1-dim. From your print out, X is an empty one dim array. Therefore, It never passed into the else clause.

 (0,) (array([], dtype=float64), array([], dtype=float64)) 

Clearly, X is one-dim and empty.

    X = []  # <---one dimension
    for i in range(len(names)):
        if type(names[i])==str or type(names1[i])==str :
            pass
        else:
            # if loop never gets here, X will remain one dimensional
            X.append([names[i],names1[i]])  # <---two dimensions
            y.append(i+1)

    X = np.array(X)  # <---still one dimension if not passed through else clause
    y = np.array(y)
    return (X,y)

def plotgraph():
    plt.figure(figsize=(10, 6))
    plt.scatter(X[:,0], X[:,1],c=y.astype(np.float),alpha=.5)
    #               ^       ^
    #               |       |
    #            Asking for two