List, Dictionary and Tuple

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List

• A storage for saving numerous elements. List can be considered as the collection of multiple variables.
• How to define a list
• The list is enclosed by [ ].
• The elements of the list is separated by ,
• The index system of the elements is started from 0.

List_a = [123, 456, 789, 10, 0, 454]

List name

elements

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Basic calling of a list

• Calling by the index

• Calling by the reverse index

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Basic operations of a list

• Duplicates the elements of a list

• Splice a list to be a sub-list

Genes[1:5:2]

Start index

length

interval

[2:5]

[1:-1]

[0:4]

[:4]

[1:5:2]

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Basic operations of a list

• Delete the elements of a list

• Generate a subset from a list

• Only a list can add to another one

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Insert elements into a list

• Replace the values of the elements in a list

• Insert a new element into a list – our intuition

• Insert a new element into a list – append, extend, insert

index

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Remove the elements from a list

• pop() – return the last element and remove it from the list

• list.remove() – remove the first matching element from a list

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Useful functions for a list

• Get the index of the first matching element in a list.

• Sort the list

• Reverse the list

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Useful functions for a list

• Get the number of elements in a list

• Get the maximum or minimum value in a list

• Count the number of a specific elements in a list

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Useful functions for a list

• Generate a list with continuous sequence of values

• Print a list as a string

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Exercise

• We have a list of genes with 2 mutated ones, could you please help us to get the genes which have mutations?

We can do it better with if…else statement and loop

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Manage a string

• List-like operations

• Reverse the string

• Replace a word in a string with another word

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Manage a string

• Make string to be a list

• Capital insensitive

• Search the first matching word of a string

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Manage a string

• Forward/backward match

This function is extremely useful to deal with fasta sequence

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Exercise

• A researcher discovered a very important gene which can heal lung cancer. But he made a mistake to show the gene sequence from 3’ to 5’. Moreover, he mixed the capital and small alphabets. Could you please help him to get the right one (from 5’ to 3’)?

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Tuple

• Tuple is a list which cannot be modified. Thus, it can be processed faster and also good for storing important information.
• How to define tuple:
• The list is enclosed by ().
• The elements of the list is separated by ,
• The index system of the elements is started from 0.

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Convert between list and tuple

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Dictionary (dict)

• Dictionary (dict) can store any types of variables including list, tuple and dictionary with corresponding unique keys. Thus, it is easy for searching and modification. But it takes more memory than list.
• How to define dictionary:
• The list is enclosed by {}.
• An element is composed of a key and a value. The key and value are separated by :
• The elements of the dictionary is separated by ,
• A dict can used a key to call its corresponding value via [].

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Manage a dictionary

• Reassign and add elements in a dict

• Deletion

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Manage a dictionary

• Extract the key information

• Extract the value information

• Extract the key and value at the same time

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Exercise

• We have 4 patients who were infected by an unknown bacteria. Today, we received a great news, the 4^th patient was recovered. So we may be able to get the plasma from him for further research. Could you please give me the patient’s information?

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