Problemas com zero-size array

[victoraguiar]

Fala galera, tudo bom? Tou tentando plotar um diagrama T-S aqui porém, ocorre um erro: ValueError: zero-size array to reduction operation minimum which has no identity. Alguém sabe como proceder? Valeu.

 

Código: 

import numpy as np
import matplotlib.pyplot as plt
import seawater as gsw

y, x = np.loadtxt(r'.txt',dtype='float',delimiter=None, unpack=True)
y1, x1 = np.loadtxt(r'.txt',dtype='float',delimiter=None, unpack=True)

sal = x
temp = x1
y = y1

smin = sal.min() - (0.01 * sal.min())
smax = sal.max() + (0.01 * sal.max())
tmin = temp.min() - (0.1 * temp.max())
tmax = temp.max() + (0.1 * temp.max())

xdim = round((smax-smin)/0.1+1,0)
ydim = round((tmax-tmin)+1,0)

dens = np.zeros((ydim,xdim))

ti = np.linspace(1,ydim-1,ydim)+tmin
si = np.linspace(1,xdim-1,xdim)*0.1+smin

fig1 = plt.figure()
ax1 = fig1.add_subplot(111)
CS = plt.contour(si, ti, dens, linestyles='dashed', colors='k')
plt.clabel(CS, fontsize=12, inline=1, fmt='%1.0f') # Label every second level
 
ax1.plot(sal,temp,'or',markersize=9)
 
ax1.set_xlabel('Salinity')
ax1.set_ylabel('Temperature (C)')

plt.show()