Graduate Program in Neuroscience

# Python Basics

# Programming Basics: Python

You will find it useful to store your data in arrays and matrices. This

will allow you to compute values, etc, and save you a lot of time. Matlab

and Python are powerful tools for working with arrays and matrices.

Gaining proficiency with one of these languages will likely save you a

lot of time in the long run.

## Defining arrays.

```
# Define a numerical array
x = [7, 9, 12, 5, 2, 13, 9];
# Define an array containing strings.
c = ['seven', 'nine', 'twelve', 'five', 'two', 'thirteen', 'nine'];
```

## For loops.

```
## For-loop examples
# Go through the values defined in a for loop and print the values to the
# command line.
for j in range(0, 10):
print(j)
# Let's loop through all of the values in the numerical array and display
# what we've found to the command line.
for value in x:
print(value)
# Now, let's do the same for the cell containing our strings.
for value in c:
print(value)
```

## While loops.

```
## While-loop examples.
done = False;
count = 0;
while count < len(x):
print(x[count])
count += 1;
```

## If-then-else statements.

```
## If-then-else statement examples
# Let's loop through all of the values in the numerical array and display
# what we've found to the command line.
for j in range(0, len(x)):
if (x[j] == 5):
print("I found 5!")
elif (x[j] == 7):
print("I found 7!")
else:
print("I found %d!" % x[j])
# Now, let's do the same for the cell containing our strings.
for j in range(0, len(c)):
if (c[j] == "five"):
print("I found five!")
elif (c[j] == "seven"):
print("I found seven!")
else:
print("I found %s!" % c[j])
```

## Searching for values in an array.

```
## Searching for values in an array.
# Search for the index numbers in the array that contain the desired
# values. If the value isn't there, it will return empty.
# For the numerical array; find values equal to 9.
tf = [i for i in range(len(x)) if x[i] == 9]
print tf
# Find all of the values greater than or equal to 7.
tf2 = [i for i in range(len(x)) if x[i] >= 7]
print tf2
tf3 = [i for i in range(len(c)) if c[i] == "nine"]
print tf3
```