## How to find position of similar numbers in a list

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Given a list of elements, with certain similar elements in it, how do I write a code in Python to find the position of all the similar elements in it? This must be done using a for loop and if conditions within the for loop.

```list1 = [5, 90, 10, 5, 100, 5]
```

So in this case, since 5 is the element that has repeats or ties, the output will be 0,3,5.

You can try to use `set` to find the unique set of elements in the `list` and then check for indexes of the repeated elements.

Try the code below:

```from collections import defaultdict

list1 = [5, 90, 10, 5, 100, 5]

set1 = set(list1)
res_dict = defaultdict(list)

for x in set1:
for i, y in enumerate(list1):
if x == y:
res_dict[x].append(i)

print res_dict
```

Output:

```{90: , 100: , 10: , 5: [0, 3, 5]}
```

Python List index(), If you provide a value for start , then end is optional. We shall look into examples, where we go through each of these scenarios in detail. Example 1: Find Index� Create a sorted list of your words and use the bisect module to identify the point in the sorted list where your word would fit according to the sorting order. Based on that position you can give the k nearest neighbours above and below to find the 2k closest words.

With `enumerate` inside list comprehension for 5,

```>>> list1 = [5, 90, 10, 5, 100, 5]
>>> all_index = [i for i, j in enumerate(list1) if j == 5]
>>> all_index
```

Output:

```[0, 3, 5]
```

With loop for all element,

```list1 = [5, 90, 10, 5, 100, 5]
result = {}
for e in list1:
result[e] = [i for i, j in enumerate(list1) if j == e]
print(result)
```

Output:

``` {90: , 10: , 100: , 5: [0, 3, 5]}
```

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Using np.where will get you what you want:

```import numpy as np

list1 = [5, 90, 10, 5, 100, 5]

data = np.array(list1)
unique = sorted(list(set(data)))

match = {}
for i in range(len(unique)):
match[unique[i]] = np.where(data == unique[i])

print(match)
>>> {5: array([0, 3, 5]), 10: array(), 90: array(), 100: array()}
```

Python, Delete elements from a Numpy Array by value or conditions in Python. No Comments Yet. Leave a Reply Cancel reply. Your� Consider a series of numbers composed of only digits 4 and 7. The first few numbers in the series are 4, 7, 44, 47, 74, 77, 444, .. etc. Given a number constructed by 4, 7 digits only, we need to find the position of this number in this series. Examples: Input : 7 Output : pos = 2 Input : 444 Output : pos = 7

Using only a for loop and if conditions:

```input_list = [5, 90, 100, 5, 100, 5]

elements = {}
result = []

for i, e in enumerate(input_list):
if e in elements:
if not elements[e]:
result.append(elements[e])
elements[e] = True
result.append(i)
else:
elements[e] = [i, False]

print(sorted(result))
```

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How to get the index of a duplicated string in a list (Python 2), A list is an ordered set of values, where each value is identified by an index. If you try to read or write an element that does not exist, you get a runtime error:. In general, you can find the K largest (or smallest) numbers in an array using a single pass for any K. The total time complexity will be O(NK), where N is the size of the array: Keep a sorted list of numbers that has at most K elements. Walk though the array and for each item: if there list is not yet full, insert the item

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