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Python 3.8+, 51 byte lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2) Testing the code: f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2) for s in "IVXLCDM": print(s, f(s)) T...

posted 7mo ago by Arpad Horvath‭ · edited 7mo ago by Arpad Horvath‭

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#6: Post edited by

Arpad Horvath‭ · 2023-10-27T14:31:11Z (7 months ago)
Thanks

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# Python 3.8+, 51 byte
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```
The [walrus operator](https://realpython.com/python-walrus-operator/) stores the index in the variable `i`, that is used in the exponent.
A much more readable version with the same logic:
```python
def f(n):
i = "IVXLCDM".index(n)
return (i%2*4+1) * 10 ** (i // 2)
~~```~~

# Python 3.8+, 51 byte
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```
The [walrus operator](https://realpython.com/python-walrus-operator/) stores the index in the variable `i`, that is used in the exponent.
A much more readable version with the same logic:
```python
def f(n):
i = "IVXLCDM".index(n)
return (i%2*4+1) * 10 ** (i // 2)
```
Thanks for [Object object]‭ for getting rid of 5 bytes.

#5: Post edited by

Arpad Horvath‭ · 2023-10-27T14:26:02Z (7 months ago)
More readable version

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# Python 3.8+, 51 byte
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```
~~The [walrus operator](https://realpython.com/python-walrus-operator/) stores the index in the variable `i`, that is used in the exponent.~~

# Python 3.8+, 51 byte
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```
The [walrus operator](https://realpython.com/python-walrus-operator/) stores the index in the variable `i`, that is used in the exponent.
A much more readable version with the same logic:
```python
def f(n):
i = "IVXLCDM".index(n)
return (i%2*4+1) * 10 ** (i // 2)
```

#4: Post edited by

Arpad Horvath‭ · 2023-10-27T14:10:41Z (7 months ago)
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~~# Python 3.8+, 62 bytes, 51 byte~~
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```

# Python 3.8+, 51 byte
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```
The [walrus operator](https://realpython.com/python-walrus-operator/) stores the index in the variable `i`, that is used in the exponent.

#3: Post edited by

Arpad Horvath‭ · 2023-10-27T14:08:03Z (7 months ago)
walrus to be able to use lambda

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~~# Python, 62 bytes~~
```python
~~lambda n:i="IVXLCDM".index(n);print((4*(i%2==1)+1)*10**(i//2))~~
```
Testing the code:
```python
~~for n in "IVXLCDM":~~
i = "IVXLCDM".index(n)
~~print(n, (4*(i%2==1)+1) * 10**(i//2))~~
```

# Python 3.8+, 62 bytes, 51 byte
```python
lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
```
Testing the code:
```python
f=lambda n:((i:="IVXLCDM".index(n))%2*4+1)*10**(i//2)
for s in "IVXLCDM":
print(s, f(s))
```

#2: Post edited by

Arpad Horvath‭ · 2023-10-26T05:46:53Z (7 months ago)

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~~# Python, 53 bytes~~
```python
~~i="IVXLCDM".index(n);print((4*(i%2==1)+1)*10**(i//2))~~
```
Testing the code:
```python
for n in "IVXLCDM":
i = "IVXLCDM".index(n)
print(n, (4*(i%2==1)+1) * 10**(i//2))
```

# Python, 62 bytes
```python
lambda n:i="IVXLCDM".index(n);print((4*(i%2==1)+1)*10**(i//2))
```
Testing the code:
```python
for n in "IVXLCDM":
i = "IVXLCDM".index(n)
print(n, (4*(i%2==1)+1) * 10**(i//2))
```

#1: Initial revision by

Arpad Horvath‭ · 2023-10-25T14:29:43Z (7 months ago)

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# Python, 53 bytes

```python
i="IVXLCDM".index(n);print((4*(i%2==1)+1)*10**(i//2))
```

Testing the code:

```python
for n in "IVXLCDM":
    i = "IVXLCDM".index(n)
    print(n, (4*(i%2==1)+1) * 10**(i//2))

```

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