import numpy as np



# Question 1 (similar to class):

# An oceanographer is studying wintertime sea surface temperature at a site on

# the east coast. For the past six years, she obtains the following values:

#

# [8.61, 7.575, 9.72, 2.087, 5.421, 1.659]

#

# In the space below, write a program that

# calculates the mean, and prints it on the screen. Use the built-in sum() and

# len() functions. Avoid using np.mean(), except to check your work. Use

# descriptive variable names -- see Section 2.12 of Python for Everybody.



values = np.array([8.61, 7.575, 9.72, 2.087, 5.421, 1.659])
print (values)
print('sum')
s=sum(values)
print(s)
print('length')
l=len(values)
print(l)
print('mean')
mean=(s/l)
print(mean)

#checking answer

vmean=np.mean(values)
print(vmean)




# Question 2:

# Write a program the calculates and prints the (unbiased) variance of the same

# SST data set and prints it to the screen. Re-use variables that you created

# in your answer to Question 1.  Avoid using np.var(), except to check your

# work. Note that the "ddof" option in np.var() needs to be modified to compute

# the unbiased variance.

print('variance')
#subtracting mean from array
var=(values-mean)
print(var)

#squaring values
sq=(var**2)
print(sq)

#taking sum of the squares
s2=sum(sq)
print(sq)

#finding degrees of freedom
print('degrees of freedom')
l2=l-1
print(l2)


#finding variance
print('variance')
variance=(s2/l2)
print(variance)

#checking variance answer
varcheck=np.var(values,ddof=1)
print(varcheck)






# Question 3:

# Write a program the calculates and prints the standard deviation of the same

# SST data set and prints it to the screen. Avoid using np.std(), except to check

# your work.

#standard deviation is the square root of the variance
stdev=np.sqrt(variance)
print(stdev)

#checking answer
stdev2=np.std(values, ddof=1)
print(stdev2)






# Question 4:

# Write a program the calculates and prints the standard error of the same

# SST data set and prints it to the screen.


#Standard error is calculated by dividing the standard deviation by the square root of the sample size
print('length')
print(l)
#calculating the square root of the sample size
sql=np.sqrt(l)
print(sql)

#calculating standard error
print('standard error')
se=(stdev/sql)
print(se)








# Question 5:

# Write a program that prints the z-scores of the same SST data set.

#z-score is calculated by subracting the mean from the array anf then dividing by the standard deviation
#subtracting mean from array
var=(values-mean)
print(var)

#standard deviation
stdev=np.sqrt(variance)
print(stdev)

#z-score var divided by stdev
print('z-score')
z=(var/stdev)
print(z)






# Question 6:

# Write a program that takes the last value from SST data set created in

# Question 1, and rounds it to the nearest tenth. Hint: help(round)

# Make sure that all of your programs in questions 1-6 still work if

# new value is added to the end of the data set.
help(round)
r=float(round(1.695,2))
print(r)

#checking to see if 1-6 still works after adding new value to the end
values = np.array([8.61, 7.575, 9.72, 2.087, 5.421, 1.659, 1.7])
print (values)
print('sum')
s=sum(values)
print(s)
print('length')
l=len(values)
print(l)
print('mean')
mean=(s/l)
print(mean)

#checking answer

vmean=np.mean(values)
print(vmean)

print('variance')
#subtracting mean from array
var=(values-mean)
print(var)

#squaring values
sq=(var**2)
print(sq)

#taking sum of the squares
s2=sum(sq)
print(sq)

#finding degrees of freedom
print('degrees of freedom')
l2=l-1
print(l2)


#finding variance
print('variance')
variance=(s2/l2)
print(variance)

#checking variance answer
varcheck=np.var(values,ddof=1)
print(varcheck)


stdev=np.sqrt(variance)
print(stdev)

#checking answer
stdev2=np.std(values, ddof=1)
print(stdev2)


print('length')
print(l)
#calculating the square root of the sample size
sql=np.sqrt(l)
print(sql)

#calculating standard error
print('standard error')
se=(stdev/sql)
print(se)

var=(values-mean)
print(var)

#standard deviation
stdev=np.sqrt(variance)
print(stdev)

#z-score var divided by stdev
print('z-score')
z=(var/stdev)
print(z)

#still works when new value is added to the end of the array


# Question 7:

# (Excercise 5 in Chapter 2 of Python for Everybody)

# Write a program which prompts the user for a Celsius temperature, convert the

# temperature to Fahrenheit, and print out the converted temperature.


c= input('Celsius temperature?')
print(c)
print(type(c))
c2=float(c)
print(type(c2))

#Celsius to Fahrenheit
print('Fahrenheit')
f=c2*(9/5)+32
print(f)





# Question 8:

# Write a program that uses input to prompt a user for their first and last names

# and then welcomes them using their initials. For example:

#

# Enter your first name: Tom

# Enter your last name: Connolly

# Hello TC!

fn=input('enter your first name')
ln=input('enter your last name')
#print(fn[0])
#print(ln[0])
print('Hello '+fn[0]+ln[0]+'!')