When using Python iterate over dictionary, the two setups using print(i, j) and print(i) seem to return the same result. Are there cases when one approach should be used over the other, or can they be used interchangeably?
Consider the following code:
desc = {'city': 'Monowi', 'state': 'Nebraska', 'county': 'Boyd', 'pop': 1}
for i, j in desc.items():
print(i, j)
for i in desc.items():
print(i)
for i, j in desc.items():
print(i, j)[1]
for i in desc.items():
print(i)[1]
Can you explain the correct way to Python iterate over dictionary and the differences, if any, between these variations?
When you want to access both keys and values in a dictionary, you should use items() for Python iterate over dictionary. This method allows you to iterate over each key-value pair.
For example:
for i, j in desc.items():
print(i, j)
In this case, i represents the key, and j represents the value. This is a clear and direct way to Python iterate over dictionary when both key and value are needed.
If you are only interested in the keys of the dictionary, you can iterate directly over the dictionary or use keys():
for i in desc:
print(I)
This loop will give you just the keys from the dictionary. Since desc is a dictionary, iterating over it by default gives you the keys. This is a simpler, more efficient way to Python iterate over dictionary if you only need the keys.
The line print(i, j)[1] and print(i)[1] won’t work as expected because indexing is being applied after the print statement. In Python, the print function returns None, and trying to index it results in an error. Instead, you should access the second element inside the loop like this:
for i, j in desc.items():
print(j) # Accessing the value directly
To summarize, the best practices for Python iterate over dictionary depend on whether you need just the keys, both keys and values, or values only. Avoid unnecessary tuple indexing or incorrect usage of print() for indexing.