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

# # DataArray - Arithmetic
# 
# We can basic arithmetic operations (plus, minus, multiplication and division) with DataArrays, both with scalars, numpy arrays and other DataArrays. The output will in all cases be a new DataArray.

# In[1]:


import mikeio


# In[2]:


fn1 = "../tests/testdata/oresundHD_run1.dfsu"
da1 = mikeio.read(fn1, items="Surface elevation")[0]
fn2 = "../tests/testdata/oresundHD_run2.dfsu"
da2 = mikeio.read(fn2, items="Surface elevation")[0]


# ## Multiply or add scalar
# 
# We can scale a DataArray or add a constant using *, +, / and -

# In[3]:


da1.values.mean()


# In[4]:


da1_A = da1 + 1
da1_B = da1 - 1
da1_A.values.mean(), da1_B.values.mean()


# In[5]:


da1_C = da1 * 2
da1_D = da1 / 2
da1_C.values.mean(), da1_D.values.mean()


# ## Difference between two DataArrays
# 
# Assume that we have two calibration runs and we wan't to find the difference...

# In[6]:


da_diff = da1-da2
da_diff.plot(title="Difference");


# In[7]:


da_diff = da1/da2
da_diff.plot(title="da1/da2");