I have the following line:
BL: {version: 2, revision: 1}
I want to parse it, so that I will get in one variable BL, and on the other, I will get
[[version, revision], [2,1]]
I have the following code:
for line in file:
print line.split(':',1)[0]; gives me the first word (BL)
print line.split(': ',1)[1]
data = json.loads(json.dumps(line.split(': ',1)[1]));
The problem is that data is not contained the data as variable, so when I do data[0], I get the char: {
What the correct way to do that?
Your JSON is not valid since it's keys are not valid (you probably want strings there).
To get around it you could do something hacky like:
# give value to non-string keys, to use in eval
version = "version"
revision = "revision"
d = eval(line.split(": ", 1)[1])
print [d.keys(), d.values()]
This requires you to know all keys in advance.
I recommend you fix your input-generating script instead.
I always avoid eval.
Related
I am trying to build a dictionary based on a larger input of text. From this input, I will create nested dictionaries which will need to be updated as the program runs. The structure ideally looks like this:
nodes = {}
node_name: {
inc_name: inc_capacity,
inc_name: inc_capacity,
inc_name: inc_capacity,
}
Because of the nature of this input, I would like to use variables to dynamically create dictionary keys (or access them if they already exist). But I get KeyError if the key doesn't already exist. I assume I could do a try/except, but was wondering if there was a 'cleaner' way to do this in python. The next best solution I found is illustrated below:
test_dict = {}
inc_color = 'light blue'
inc_cap = 2
test_dict[f'{inc_color}'] = inc_cap
# test_dict returns >>> {'light blue': 2}
Try this code, for Large Scale input. For example file input
Lemme give you an example for what I am aiming for, and I think, this what you want.
File.txt
Person1: 115.5
Person2: 128.87
Person3: 827.43
Person4:'18.9
Numerical Validation Function
def is_number(a):
try:
float (a)
except ValueError:
return False
else:
return True
Code for dictionary File.txt
adict = {}
with open("File.txt") as data:
adict = {line[:line.index(':')]: line[line.index(':')+1: ].strip(' \n') for line in data.readlines() if is_number(line[line.index(':')+1: ].strip('\n')) == True}
print(adict)
Output
{'Person1': '115.5', 'Person2': '128.87', 'Person3': '827.43'}
For more explanation, please follow this issue solution How to fix the errors in my code for making a dictionary from a file
As already mentioned in the comments sections, you can use setdefault.
Here's how I will implement it.
Assume I want to add values to dict : node_name and I have the keys and values in two lists. Keys are in inc_names and values are in inc_ccity. Then I will use the below code to load them. Note that inc_name2 key exists twice in the key list. So the second occurrence of it will be ignored from entry into the dictionary.
node_name = {}
inc_names = ['inc_name1','inc_name2','inc_name3','inc_name2']
inc_ccity = ['inc_capacity1','inc_capacity2','inc_capacity3','inc_capacity4']
for i,names in enumerate(inc_names):
node = node_name.setdefault(names, inc_ccity[i])
if node != inc_ccity[i]:
print ('Key=',names,'already exists with value',node, '. New value=', inc_ccity[i], 'skipped')
print ('\nThe final list of values in the dict node_name are :')
print (node_name)
The output of this will be:
Key= inc_name2 already exists with value inc_capacity2 . New value= inc_capacity4 skipped
The final list of values in the dict node_name are :
{'inc_name1': 'inc_capacity1', 'inc_name2': 'inc_capacity2', 'inc_name3': 'inc_capacity3'}
This way you can add values into a dictionary using variables.
I am using a new script (a) to extract information from an old script (b) to create a new file (c). I am looking for an equal sign in the old script (b) and want to modify the modification script (a) to make it automated.
The string is
lev1tolev2 'from=e119-b3331l1 mappars="simp:180" targ=enceladus.bi.def.3 km=0.6 lat=(-71.5,90) lon=(220,360)'
It is written in python 3.
The current output is fixed at
cam2map from=e119-b3331l1 to=rsmap-x map=enc.Ink.map pixres=mpp defaultrange=MAP res=300 minlat=-71.5 maxlat=90 minlon=220 maxlon=360
Currently, I have the code able to export a string of 0.6 for all of the iterations of lev1tolev2, but each one of these is going to be different.
cam2map = Call("cam2map")
cam2map.kwargs["from"] = old_lev1tolev2.kwargs["from"]
cam2map.kwargs["to"] = "rsmap-x"
cam2map.kwargs["map"] = "enc.Ink.map"
cam2map.kwargs["pixres"] = "mpp"
cam2map.kwargs["defaultrange"] = "MAP"
**cam2map.kwargs["res"] = float((old_lev1tolev2.kwargs["km"]))**
cam2map.kwargs["minlat"] = lat[0]
cam2map.kwargs["maxlat"] = lat[1]
cam2map.kwargs["minlon"] = lon[0]
cam2map.kwargs["maxlon"] = lon[1]
I have two questions, why is this not converting the string to a float? And, why is this not iterating over all of the lev1tolev2 commands as everything else in the code does?
The full code is available here.
https://codeshare.io/G6drmk
The problem occurred at a different location in the code.
def escape_kw_value(value):
if not isinstance(value, str):
return value
elif (value.startswith(('"', "'")) and value.endswith(('"', "'"))):
return value
# TODO escape the quote with \" or \'
#if value.startswith(('"', "'")) or value.endswith(('"', "'")):
# return value
if " " in value:
value = '"{}"'.format(value)
return value
it doesn't seem to clear to me, but from you syntax here :
**cam2map.kwargs["res"] = float((old_lev1tolev2.kwargs["km"]))**
I'd bet that cam2map.kwargs["res"] is a dict, and you thought that it would convert every values in the dict, using the ** syntax. The float built-in should then be called in a loop over the elements of the dict, or possible a list-comprehension as here :
cam2map.kwargs["res"] = dict()
for key, value in old_lev1tolev2.kwars["res"].items():
cam2map.kwargs["res"][key] = float(value)
Edit :
Ok so, it seems you took the string 'from=e119-b3331l1 mappars="simp:180" targ=enceladus.bi.def.3 km=0.6 lat=(-71.5,90) lon=(220,360)'
And then thought that calling youstring.kwargs would give you a dict, but it won't, you can probably parse it to a dict first, using some lib, or, you use mystring.split('=') and then work your way to a dict first, like that:
output = dict()
for one_bit in lev_1_lev2.split(' '):
key, value = one_bit.split('=')
output[key] = value
I am attempting to generate a URL link in the following format using urllib and urlencode.
<img src=page.psp?KEY=%28SpecA%2CSpecB%29&VALUE=1&KEY=%28SpecA%2C%28SpecB%2CSpecC%29%29&VALUE=2>
I'm trying to use data from my dictionary to input into the urllib.urlencode() function however, I need to get it into a format where the keys and values have a variable name, like below. So the keys from my dictionary will = NODE and values will = VALUE.
wanted = urllib.urlencode( [("KEY",v1),("VALUE",v2)] )
req.write( "<a href=page.psp?%s>" % (s) );
The problem I am having is that I want the URL as above and instead I am getting what is below, rather than KEY=(SpecA,SpecB) NODE=1, KEY=(SpecA,SpecB,SpecC) NODE=2 which is what I want.
KEY=%28SpecA%2CSpecB%29%2C%28%28SpecA%2CSpecB%29%2CSpecC%29&VALUE=1%2C2
So far I have extracted keys and values from the dictionary, extracted into tuples, lists, strings and also tried dict.items() but it hasn't helped much as I still can't get it to go into the format I want. Also I am doing this using Python server pages which is why I keep having to print things as a string due to constant string errors. This is part of what I have so far:
k = (str(dict))
ver1 = dict.keys()
ver2 = dict.values()
new = urllib.urlencode(function)
f = urllib.urlopen("page.psp?%s" % new)
I am wondering what I need to change in terms of extracting values from the dictionary/converting them to different formats in order to get the output I want? Any help would be appreciated and I can add more of my code (as messy as it has become) if need be. Thanks.
This should give you the format you want:
data = {
'(SpecA,SpecB)': 1,
'(SpecA,SpecB,SpecC)': 2,
}
params = []
for k,v in data.iteritems():
params.append(('KEY', k))
params.append(('VALUE', v))
new = urllib.urlencode(params)
Note that the KEY/VALUE pairings may not be the order you want, given that dicts are unordered.
http://www.learnpython.org/Serialization_using_JSON_and_pickle
Here are the instructions:
The aim of this exercise is to print out the JSON string with key-value pair "Me" : 800 added to it.
And below is the starting code, which we should modify.
#Exercise fix this function, so it adds the given name and salary pair to the json it returns
def add_employee(jsonSalaries, name, salary):
# Add your code here
return jsonSalaries
#Test code - shouldn't need to be modified
originalJsonSalaries = '{"Alfred" : 300, "Jane" : 301 }'
newJsonSalaries = add_employee(originalJsonSalaries, "Me", 800)
print(newJsonSalaries)
I'm completely lost. The JSON lesson was brief, at best. The issue I seem to be running in to here is that orginalJsonSalaries is defined as a string (containing all sort of unnecessary symbols like brackets. In fact, I think if the single quotes surrounding its definition were removed, originalJsonSalaries would be a dictionary and this would be a lot easier. But as it stands, how can I append "Me" and 800 to the string and still maintain the dictionary-like formatting?
And yes, I'm very very new to coding. The only other language I know is tcl.
EDIT:
OK, thanks to the answers, I figured out I was being dense and I wrote this code:
import json
#Exercise fix this function, so it adds the given name and salary pair to the json it returns
def add_employee(jsonSalaries, name, salary):
# Add your code here
jsonSalaries = json.loads(jsonSalaries)
jsonSalaries["Me"] = 800
return jsonSalaries
#Test code - shouldn't need to be modified
originalJsonSalaries = '{"Alfred" : 300, "Jane" : 301 }'
newJsonSalaries = add_employee(originalJsonSalaries, "Me", 800)
print(newJsonSalaries)
This does not work. For whatever reason, the original dictionary keys are formatted as unicode (I don't know where that happened), so when I print out the dictionary, the "u" flag is shown:
{u'Jane': 301, 'Me': 800, u'Alfred': 300}
I have tried using dict.pop() to replace the key ( dict("Jane") = dict.pop(u"Jane") ) but that just brings up SyntaxError: can't assign to function call
Is my original solution incorrect, or is this some annoying formatting issue and how to resolve it?
The page you linked to says exactly how to do this:
In order to use the json module, it must first be imported:
import json
[...]
To load JSON back to a data structure, use the "loads" method. This method takes a string and turns it back into the json object datastructure:
print json.loads(json_string)
They gave you a string (jsonSalaries). Use json.loads to turn it into a dictionary.
Your last question is a new question, but... When you print a dictionary like that you are just using the fact that python is nice enough to show you the contents of its variables in a meaningful way. To print the dictionary in your own format, you would want to iterate through the keys and print the key and value:
for k in newJsonSalaries:
print("Employee {0} makes {1}".format(k, newJsonSalaries[k]))
There are other problems in your code....
It is weird to load the JSON inside the add employee function. That should be separate...
Also, in your add_employee() function you are hardwired always to add the same values of Me and 800 instead of using the name and salary variables that are passed in, so that line should be:
jsonSalaries[name] = salary
Use this:
import json
def add_employee(jsonSalaries, name, salary):
# Add your code here
jsonSalaries = json.loads(jsonSalaries)
jsonSalaries[name] = salary
jsonSalaries = json.dumps(jsonSalaries)
return jsonSalaries
#Test code - shouldn't need to be modified
originalJsonSalaries = '{"Alfred" : 300, "Jane" : 301 }'
newJsonSalaries = add_employee(originalJsonSalaries, "Me", 800)
print(newJsonSalaries)
Add this before return jsonSalaries:
jsonSalaries = json.dumps(jsonSalaries)
How do I use string formatting to call information from a dictionary?
Here's what I attempted so far (probably quite bad...)
value = raw_input("Indicate a number: ")
print number_stats["chm%"] % (value,)
The dictionary number_stats holds information about values "chm1", "chm2", etc.
I get a key error, which confuses me because the item chm1 is definitely stored in my dictionary.
Is there a better way to do this?
When you do number_stats["chm%"] % (value,), you are doing number_stats["chm%"] first and then applying % (value,) to the result. What you want is to apply the % directly to the string:
number_stats["chm%s" % (value,)]
Note that you need %s; % by itself is not a valid string substitution.
However, there is probably a better way to do it. Why does your dictionary have keys like "chm1" and "chm2" instead of just having the numbers be the keys themselves (i.e., have keys 1 and 2)? Then you could just do number_stats[value]. (Or if you read value from raw_input you'd need number_stats[int(value)]
Use like this. You have to use string formatting inside square brackets
>>> number_stats={'a1': 1}
>>>
>>> print number_stats['a%s' % 1]
1
>>>
print number_stats["chm%s" % (value)]
should work.
But you should do this instead:
print number_stats.get("chm%s" % (value), "some_default_value")
To avoid crashing if the user enters an invalid key. See this for more info on the get method.
As an alternative you could use the string format method...
value = input("Indicate a number: ")
print number_stats["chm{}".format(value)]