Two dictionaries - deleting values from a list

[crumpet]

Hi folks,

Just hoping someone can point me in the right direction with this one.
Say I have these key:value pairs in a dictionary, d1:

d1 = {fruit:['apples', 'bananas','oranges','tomatoes'], vegetables:['carrots','lettuces']}

And I wanted to remove a list (containing tomatoes, oranges) from the value of the key fruit and add those list contents to vegetables.

fruit_veg_list = ['tomatoes','oranges']

Now I've worked out concatenations just fine, so I've got that list adding to "vegetables". That's the easy part.

Trouble is, when trying a del or remove or similar, to get rid of the fruit_veg_list values from the key fruit, I simply can't work out how to do it. This makes sense, since the list itself doesn't exist in fruit's values! Yet I can't work out a way to take those items out of the list and remove them one by one.

Is there a sort of "reverse concatenation" for this situation? I'm a bit stuck but if someone could guide me in the right direction it would be much appreciated.

[daniwebnewbie]

I'm not quite sure I understand your exact question, but maybe this will help:

If you wanted to remove orange from fruit's dictionary entry try:

del d1['fruit'][2]

to add orange over to vegetables:

d1['vegetables'].append('orange')

To go even further, to get the correct index programmatically so you don't have to just 'know' orange's position in the fruit's list use:

#if fruittoremove exists in the fruit list, find its index
if fruittoremove in d1['fruit']:
    dIndex=d1['fruit'].index(fruittoremove)
    return dIndex

#delete item using the index we just found
del d1['fruit'][dIndex]

#add item to other list
d1['vegetables'].append('fruittoremove')

You can even combine them into single lines of code:

#itemTOmove can be any fruit
if itemTOmove in d1['fruits']:
    del d1['fruits'][d1['fruits'].index(itemTOremove)]
    d1['vegetables'].append(itemTOremove)

Is that enough to get you on the right track?

[crumpet]

It is! I've worked out a way to adapt your individual value coding to remove the values specified list (using a for loop). It's working quite well.

Many thanks for your help!

[daniwebnewbie]

And just for fun, you can turn it into a handy function:

#itemtomove=item you wish to move between lists
#dictname=source dictionary name
#srclist=source list name(one to delete from)
#destlist=destination list (one to append to)

def movelistitem(dictname,itemtomove,,srclist,destlist):
    if itemtomove in dictname[srclist]:
        del dictname[srclist][dictname[srclist].index(itemtomove)]
        dictname[destlist].append(itemtomove)
#usage to move entry "apple" from "fruit" to "vegetable" list, in the dictionary named d1
movelistitem('d1','apple','fruit','vegetables']

If there are any mistakes, please forgive me. Today is my first day using python!

Thanks!

[crumpet]

If there are any mistakes, please forgive me. Today is my first day using python!

This is my third week of doing it, and you understood how to do that dictionary/list operation better than I did! Thanks again for a detailed and easy to understand reply.

[daniwebnewbie]

If you found this post useful please "mark this post as solved".