# Revision history [back]

### How to use DiscreteRandomVariable covariance method?

I'd like to take advantage of covariance() method of DiscreteRandomVariable class, yet, I can't find any example on the internet how to properly use it.

My understanding is that this should work:

text1 = AlphabeticStrings().encoding("AB") text2 = AlphabeticStrings().encoding("BA") text1freq = frequency_distribution(text1) text2freq = frequency_distribution(text2) text1freq.covariance(text2freq)

/usr/lib/python2.7/site-packages/sage/probability/random_variable.pyc in covariance(self, other) 187 Omega = self.probability_space() 188 if Omega != other.probability_space(): --> 189 raise ValueError("Argument other (= %s) must be defined on the same probability space." % other) 190 muX = self.expectation() 191 muY = other.expectation()

ValueError: Argument other (= Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}) must be defined on the same probability space.

But... Logically (not technically) both text1freq and text2freq are the same probability space:

sage: text1freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

sage: text2freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

### How to use DiscreteRandomVariable covariance method?

I'd like to take advantage of covariance() method of DiscreteRandomVariable class, yet, I can't find any example on the internet how to properly use it.

My understanding is that this should work:

text1 = AlphabeticStrings().encoding("AB") AlphabeticStrings().encoding("AB")

text2 = AlphabeticStrings().encoding("BA") AlphabeticStrings().encoding("BA")

text1freq = frequency_distribution(text1) frequency_distribution(text1)

text2freq = frequency_distribution(text2) frequency_distribution(text2)

text1freq.covariance(text2freq)

/usr/lib/python2.7/site-packages/sage/probability/random_variable.pyc in covariance(self, other) 187 Omega = self.probability_space() 188 if Omega != other.probability_space(): --> 189 raise ValueError("Argument other (= %s) must be defined on the same probability space." % other) 190 muX = self.expectation() 191 muY = other.expectation()

ValueError: Argument other (= Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}) must be defined on the same probability space.

But... Logically (not technically) both text1freq and text2freq are the same probability space:

sage: text1freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

sage: text2freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

### How to use DiscreteRandomVariable covariance method?

I'd like to take advantage of covariance() method of DiscreteRandomVariable class, yet, I can't find any example on the internet how to properly use it.

My understanding is that this should work:

text1 = AlphabeticStrings().encoding("AB")

text2 = AlphabeticStrings().encoding("BA")

text1freq = frequency_distribution(text1)

text2freq = frequency_distribution(text2)

text1freq.covariance(text2freq)

/usr/lib/python2.7/site-packages/sage/probability/random_variable.pyc in covariance(self, other) other)

187         Omega = self.probability_space()
188         if Omega != other.probability_space():


--> 189 raise ValueError("Argument other (= %s) must be defined on the same probability space." % other) other)

190         muX = self.expectation()
191         muY = other.expectation()other.expectation()


ValueError: Argument other (= Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}) must be defined on the same probability space.

But... Logically (not technically) both text1freq and text2freq are the same probability space:

sage: text1freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

sage: text2freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

### How to use DiscreteRandomVariable covariance method?

I'd like to take advantage of covariance() method of DiscreteRandomVariable class, yet, I can't find any example on the internet how to properly use it.

My understanding is that this should work:

text1 = AlphabeticStrings().encoding("AB")

text2 = AlphabeticStrings().encoding("BA")

text1freq = frequency_distribution(text1)

text2freq = frequency_distribution(text2)

text1freq.covariance(text2freq)

/usr/lib/python2.7/site-packages/sage/probability/random_variable.pyc in covariance(self, other)

187         Omega = self.probability_space()

188         if Omega != other.probability_space():


--> 189 raise ValueError("Argument other (= %s) must be defined on the same probability space." % other)

190         muX = self.expectation()

191         muY = other.expectation()


ValueError: Argument other (= Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}) must be defined on the same probability space.

But... Logically (not technically) both text1freq and text2freq are the same probability space:

sage: text1freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

sage: text2freq Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}

### How to use DiscreteRandomVariable covariance method?

I'd like to take advantage of covariance() method of DiscreteRandomVariable class, yet, I can't find any example on the internet how to properly use it.

My understanding is that this should work:

text1 = AlphabeticStrings().encoding("AB") AlphabeticStrings().encoding("AB")
text2 = AlphabeticStrings().encoding("BA") AlphabeticStrings().encoding("BA")
text1freq = frequency_distribution(text1) frequency_distribution(text1)
text2freq = frequency_distribution(text2) text1freq.covariance(text2freq)frequency_distribution(text2)
text1freq.covariance(text2freq)


/usr/lib/python2.7/site-packages/sage/probability/random_variable.pyc in covariance(self, other) other)
187         Omega = self.probability_space()
188         if Omega != other.probability_space():
--> 189             raise ValueError("Argument other (= %s) must be defined on the same probability space." % other) other)
190         muX = self.expectation()
191         muY = other.expectation()
ValueError: Argument other (= Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}) must be defined on the same probability space.space.


But... Logically (not technically) both text1freq and text2freq are the same probability space:

sage: text1freq
Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000} 0.500000000000000}
sage: text2freq
Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}0.500000000000000} 6 retagged FrédéricC 5086 ●3 ●42 ●110

### How to use DiscreteRandomVariable covariance method?

I'd like to take advantage of covariance() method of DiscreteRandomVariable class, yet, I can't find any example on the internet how to properly use it.

My understanding is that this should work:

text1 = AlphabeticStrings().encoding("AB")
text2 = AlphabeticStrings().encoding("BA")
text1freq = frequency_distribution(text1)
text2freq = frequency_distribution(text2)
text1freq.covariance(text2freq)


/usr/lib/python2.7/site-packages/sage/probability/random_variable.pyc in covariance(self, other)
187         Omega = self.probability_space()
188         if Omega != other.probability_space():
--> 189             raise ValueError("Argument other (= %s) must be defined on the same probability space." % other)
190         muX = self.expectation()
191         muY = other.expectation()

ValueError: Argument other (= Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}) must be defined on the same probability space.


But... Logically (not technically) both text1freq and text2freq are the same probability space:

sage: text1freq
Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}
sage: text2freq
Discrete probability space defined by {A: 0.500000000000000, B: 0.500000000000000}