from math import sin, cos
x = pi /4
1_val = sin^2( x ) + cos^2( x )
print 1_VAL

# Fix 1: pi needs to be imported from the math module before it can be used in the line below.
from math import sin, cos, pi

x = pi /4

# Fix 2: 1_val is not a valid variable name - it cannot start with a number
# Fix 3: raising something to a power is done using **, not ^
# Fix 4: when calling sin or cos, it's name must be followed by the arguments in brackets. If we want to represent $\sin^2(x)$
# in Python, we have to write it like $\sin(x)^2$, i.e. sin(x)**2.
val = sin(x)**2 + cos(x)**2

# Fix 5: variable names are case-sensitive in Python. val is not the same as VAL.
print val

n = 101 # The number of values
start = -1.0
end = 1.0
dx = (end-start)/(n-1) # The distance between each value

values = [start + i*dx for i in range(n)]
print values

from numpy import linspace
values_numpy = linspace(start, end, n)

for v in values_numpy:
    print "%.2f" % (v)
    

from numpy import *
from pylab import *
%pylab inline
def f(x, t):
    return exp(-(x-3*t)**2)*sin(3*pi*(x-t))

n = 1000
xarray = linspace(-3, 10, n)

for t in [0, 1, 2]:
    plot(xarray, f(xarray, t), label=r"$t$ = %.1f" % (t))
xlabel(r"$x$")
ylabel(r"$f(x,t)$")
legend(loc="best")
show()

from numpy import *
f = open("seismic.dat", "r")

magnitude = []
for line in f:
    s = line.split()
    magnitude.append(float(s[-1])) # The last column is the "magnitude"
magnitude = array(magnitude)

f.close()

print magnitude

count = 0
for m in magnitude:
    if m > 6.0:
        count += 1
print "There are %d earthquakes above magnitude 6.0" % (count)

f = open("human_evolution.txt", "r")

humans = {}

for line in f:
    # Ignore lines that don't start with "H."
    if(line[0:2] != "H."):
        continue
    
    # Get each column and strip out leading and trailing whitespace
    name = line[0:21].strip()
    lived = line[21:37].strip()
    height = line[37:50].strip()
    mass = line[50:62].strip()
    brain_volume = line[62:].strip()
    
    # Add to dictionary
    humans[name] = [lived, height, mass, brain_volume]
f.close()

# Test
print humans["H. habilis"]

print "%25s %25s %25s %25s %25s" % ("Species", "Lived when (M. years)", "Adult height (m)", "Adult mass (kg)", "Brain volume (cm**3)")
for human in humans:
    data = humans[human]
    print "%25s %25s %25s %25s %25s" % (human, data[0], data[1], data[2], data[3])