#!/usr/bin/env python
# coding: utf-8

# ## Using parameters `norm, vmain, vmax` and `cmap` in `geom_imshow()`
# 
# You can use parameters `norm, vmain, vmax` and `cmap` when rendering grayscale images.
# 
# A grayscale image is specified by Numpy's 2D array where each element's value 
# represents the luminance of corresponding pixel in the image.

# In[1]:


import numpy as np

from lets_plot import *


# In[2]:


LetsPlot.setup_html()


# In[3]:


# Generate 2D Numpy arrays. 
# First two arrays both contain float numbers but have different range of values.
# The 3rd array contains int-s.
arr_f0 = np.linspace(.3, .7, 30).reshape(1, -1)
arr_f1 = np.linspace(30., 170., 30).reshape(1, -1)
arr_i = np.linspace(30, 170, 30, dtype=int).reshape(1, -1)


# In[4]:


print("arr_f0: shape {}, data range [{}-{}] {}".format(arr_f0.shape, arr_f0.min(), arr_f0.max(), arr_f0.dtype))
print("arr_f1: shape {}, data range [{}-{}] {}".format(arr_f1.shape, arr_f1.min(), arr_f1.max(), arr_f1.dtype))
print("arr_i : shape {}, data range [{}-{}] {}".format(arr_i.shape, arr_i.min(), arr_i.max(), arr_i.dtype))


# In[5]:


# Setup suitable plot options for the demo.
p = (ggplot() + ggsize(450, 60) + geom_rect(xmin=-0.5, ymin=-0.5, xmax=29.5, ymax=0.5, color="black", alpha=0) + 
coord_cartesian() + theme_void())


# #### Image normalization
# 
# By default, `geom_imshow()` applies a linear scaling to transform data values to range [0-255].

# In[6]:


(p + geom_imshow(arr_f0)).show()
(p + geom_imshow(arr_f1)).show()
(p + geom_imshow(arr_i)).show()


# ## 
# 
# You can disable image normalization using the `norm` parameter.

# In[7]:


(p + geom_imshow(arr_f0, norm=False)).show()
(p + geom_imshow(arr_f1, norm=False)).show()
(p + geom_imshow(arr_i, norm=False)).show()


# #### Define normalization range using `vmin, vmax` parameters

# In[8]:


# Set upper limit less than the data max value.
(p + geom_imshow(arr_f0, vmax=.5)).show()
(p + geom_imshow(arr_f1, vmax=100)).show()
(p + geom_imshow(arr_i, vmax=100)).show()


# In[9]:


# Set limits wider than the data entire range.
(p + geom_imshow(arr_f0, vmin=.4, vmax=.6)).show()
(p + geom_imshow(arr_f1, vmin=70, vmax=120)).show()
(p + geom_imshow(arr_i, vmin=50, vmax=150)).show()


# #### Colormaps

# In[10]:


(p + geom_imshow(arr_f0, cmap="magma")).show()
(p + geom_imshow(arr_f1, cmap="viridis")).show()
(p + geom_imshow(arr_i, cmap="plasma")).show()