Python-lists
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parsing lists in python
(back to python-datastructures)
Example #1 (some basic list manipulation)
# # # python list examples # # #1 one-dimensional ('flat/unnested') lists list1 = [1,2,3.14,'red','green'] # NOTE#1: strings may be surrounded by apostrophes or quotes or mixed # the output will convert quotes to apostrophes # #goodlist = [1,2,3.14,'red','green'] # strings with apostrophes #goodlist = [1,2,3.14,'red',"green"] # mixed apostrophes and quotes #goodlist = [1,2,3.14,"red","green"] # all quotes # NOTE#2: don't surround lists with quotes or apostrophes! # #wronglist = '[1,2,3.14,"red","green"]' # list surrounded by apostrophes #wronglist = "[1,2,3.14,'red','green']" # list surrounded by quotes print('list1: ' + str(list1) ) # NOTE#3: concatenate a list to a string by surrounding it with 'str()' # # print('list1: ' + list1) # incorrect # print('list1: ' , list1) # ok, but shows parenthesis and quotes from string # print('list1: ' + str(list1)) # correct # print(list1) # correct (but not concatenated) for x in list1: print(x) print('') print('') print ('show 4th element: ' + str(list1[3])) print('') print('modify 4th element from \'red\' to \'blue\'') list1[3] = 'blue' print('') print ('show 4th element: ' + str(list1[3])) print('') print('') print('add new element \'orange\' at the end:') list1.append('orange') print('') print('list1: ' + str(list1)) print('') print('') print('insert new element \'17\'at the beginning:') list1.insert(0,17) print('') print('list1: ' + str(list1)) print('') print('') print('delete element with name \'green\':') list1.remove('green') print('') print('list1: ' + str(list1)) print('') print('') # NOTE#4: if a list contains multiple elements with the same value then 'remove' only removes the first matching element print('delete the third element:') list1.pop(2) print('') print('list1: ' + str(list1)) print('') print('') # NOTE#5: use 'pop()' to delete the last element
Example #2 (nested lists)
# # # python list examples # # #2 - nested lists list2 = ['joe', 186, ['swimming', 'running'], [1983,2001,2018], 5, 2] print('list2: ' + str(list2) ) for x in list2: print(x) print('') print('') print('iterate over the third element (index 2)') for x in list2[2]: print(x) print('') print('') print('show the length of the list') print('list2: ' + str(list2) ) print('length: ' + str(len(list2)) + ' (counting nested lists as 1)' ) print('') print('') print('show which elements are lists:') for x in list2: if isinstance(x, list): print(str(x) + ' is a list') else: print(str(x) + ' is not a list') print('') print('') print('list2: ' + str(list2) ) print('add the element \'walking\' to the list at index 2:') list2[2].append('walking') print('list2: ' + str(list2) ) print('') print('') print('list2: ' + str(list2) ) print('remove the first element from the list at index 3:') list2[3].pop(0) print('list2: ' + str(list2) ) print('') print('')
Example #3 (bigger nested list)
# # # python list examples # # #3 - bigger nested list list3 = [[110.3, 111.5,110.1, 110.2],[110.2,112.7,109.4,111.6],[111.6,109.3,110.8,111.5]] print('list3: ' + str(list3) ) print('') print('print each nested list:') for x in list3: print(x) print('') print('') print('only show the second and third element of each nested list') for x in list3: print(x[1], x[2]) print('') print('') print('print the index position and the first element of each nested list') for (i,x) in enumerate(list3): print(i, x[0]) print('') print('')
Example #4 (list containing a dictionary)
# # # python list examples # # #4 - list containing a dictionary list4 = [{'symbol': 'ETHBTC', 'price': '0.03014900'}, {'symbol': 'LTCBTC', 'price': '0.00413500'}] print('list4: ' + str(list4) ) print('') print('print each nested dictionary:') for x in list4: print(x) print('') print('') # NOTE: below is an example of parsing a dictionary, which is not a list. # See examples for dictionaries for more details # print('iterate through each dictionary') for x in list4: marketname = x['symbol'] price = x['price'] print('market name: ' + str(marketname)) print('price: ' + str(price)) print('') print('') print('')