Make histogram from data in python -

i trying make histogram data saved in .dat file: have made other types of plots, when trying make histogram receive error: valueerror: x has 1 data point. bins or range kwarg must given. table has (many) more 1 data point! code below...

import numpy  np import matplotlib.pyplot plt  a=open('/24_5_15b.dat','r')  header0=a.readline()  w1=[] w2=[]  line in a:     line=line.strip()     columns=line.split()     w1=float(columns[13])     w2=float(columns[15])      w1=np.asarray(w1)     w2=np.asarray(w2)         n, bins, patches = plt.hist(w1, 20, normed=1, histtype='bar', rwidth=0.8)  plt.show()  

when ask print w1 prints values. numbers floats - make difference? thanks...

from looks of this, trying plot histogram first line:

for line in a:     ...     n, bins, patches = plt.hist(w1, 20, normed=1, histtype='bar', rwidth=0.8) 

to make histogram, need pass of data, not 1 @ time.

i recommend using genfromtxt too, can use like:

a = np.genfromtxt('/24_5_15b.dat')  # delimiter " " default w1 = a[:,13] w2 = a[:,15]  plt.hist(w1, ...)