problem_set_1_arrays.md

Using NumPy Arrays

Problems

These are just some basic array manipulation problems to get you used to working with NumPy arrays.

Set 1

1. Create a NumPy array of the integers 1 through 7.
2. Set the first and last elements in the array to zero.
3. Use .size to determine the length of the array.
4. Sum all of the integers in the array.
5. Using the results from parts 3 and 4, find the average of the array.

Set 2

1. Create a 1D NumPy array of 10,000 elements, all initially set to 0.0.
2. Use a while loop and set every 101st element equal to 1.0. (indices 0, 101, 202, 303, ...).
3. Change the shape of the array to be 100 x 100.
4. Use a for loop to set the first element of every row equal to the sum of all the values in that row.
5. Create a new array from the first elements in each of your rows. (HINT: You can make an array from a list.)
6. Take the product of all the elements in your new array.

Set 3

1. Use arange to create an array of decimals from zero to 26. (HINT: dtype=float)
2. Reshape that array to be a 3 x 3 x 3 multi-dimensional array.
3. Print the first and last element in the array, using three indexes.
4. Using three for loops, divide every number by the sum of all 3 elements in its row.
5. Calculate the sum of all the elements in the array.
6. Create a new array, where every element is the square root of the old one.
7. Calculate the product of all the elements in your new array.

Set 4

1. Use np.ones to create an array, a, which is five elements long.
2. Use np.arange to create an array, b, which is the integers from 2 to 6 (five elements long).
3. Use np.arange to create an array, c, which is the even integers 2 to 12. (HINT: With range, you could do: range(min, max, step).)
4. Use np.arange to creat3 an array, d, which is the float values of the integers from 1 to 5.
5. Create a new array: x = c + a - b.
6. What is the value of d - x?

Solutions

• NumPy Arrays - Solutions

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